In gas-shielded fusion welding, a powerful electric arc is used as the main tool. In the arc, electrical energy is converted into thermal energy, the density of which is sufficient for local melting of the base metal. In atmospheric conditions (21% O 2 +78% N 2), the welding zone must be reliably protected from saturation of the weld metal with oxygen and nitrogen from the air, which, as a rule, worsen its properties. Shielding gases supplied through the nozzle displace air and thus protect the weld pool and electrode. To fill the gap between the joined edges of the parts or to cut the edges and regulate the composition of the weld metal, filler metal or electrode wire is fed into the melting zone. The principle of arc welding with a non-consumable tungsten electrode in shielding gas is shown in (Fig. 3)

Fig.3
The principle of arc welding with a non-consumable tungsten electrode in shielding gas

Argon welding is predominantly performed with a tungsten electrode in an inert gas Ar (TIG) and less often in He, in active gases N 2 and H 2 or in CO 2 with a carbon electrode. Welding can be performed without an additive (IN) or with an additive (INp) from solid and non-solid flux-cored or activated wires. Depending on the type of current, the type of arcs, their number and external influences on it, welding methods can be distinguished: with direct, pulsed or alternating current, with an arc of direct, indirect and combined action; superficial, submerged and penetrating arc; free and compressed; without exposure to an external magnetic field and in a magnetic field; with and without arc oscillations; at reduced pressure (in vacuum) and at increased pressure; single- and multi-arc, etc.
The main types, structural elements and dimensions of welded joints made of steels, as well as alloys on iron-nickel and nickel bases, performed by gas-shielded arc welding are specified in GOST 14771
Depending on the level of mechanization and automation of the process, welding is distinguished:
- manual, in which all burner movements are performed manually;
- mechanized, in which the torch movements are performed manually and the wire feed is mechanized (limited for TIG);
- automated, in which all movements of the torch and wire feeding are mechanized, and the welding process is controlled by the welding operator;
- automatic (robotic), in which the welding process is controlled without the direct participation of the welding operator.

The influence of shielding gases on the technological properties of the arc.

The technological properties of the arc significantly depend on the physical and chemical properties of shielding gases, the composition of the electrode and welded metals, parameters and other welding conditions.
When arc welding the following is used:
- inert gases Ar and He and their mixtures Ar + He,
- active CO 2, N 2, H 2,
- mixtures of inert and active Ar + O 2, Ar + CO 2, Ar + O 2 + CO 2,
- mixtures of active gases CO 2 + O 2.
The physical properties of protective gases (Table 1) and the metal of the electrodes have different effects on the properties of the arc with a non-consumable “hot” cathode (W-arc) and the arc with a consumable “cold” cathode (Me-arc).

Table 1

Technological properties of the arc

in protective gases the following criteria are determined:
- electrical properties of the arc (near-electrode voltage drops, tension in the arc column, electron emission, ionization, etc.);
- arc stability;
- the shape of the arc column, its spatial stability;
- melting of the electrode metal and the type of its transfer;
- spattering of electrode metal and weldability of splashes;
- melting of the base metal and formation of a weld (depth and shape of penetration, height and shape of the bead, cleanliness of its surface);
- efficiency of protection of the welding zone (oxygen and nitrogen content in the weld, loss of alloying elements);
- resistance of the seam against the formation of porosity. Let us consider the influence of the physical properties of gases and welded metals (Table 1) on the technological properties of the arc.

welding equipment

According to their purpose, welding equipment is divided into universal, special and specialized. Let us briefly consider the principles of the layout of universal, general-purpose welding equipment that is produced in series.
The welding equipment includes a welding current source and a welding machine. Its components and their functions are determined mainly by the level of mechanization and automation of the process, the parameters of the welding mode, the need for their installation and adjustment in the setup and welding mode.
The parameters can be divided into electrical (lc, Uc) and mechanical (d3H, Lд.у., Vc, dnn, Vnn, qr).
The main parameters of automated arc welding with a tungsten electrode in inert gases Ar or He (TIG) are:
1. Welding current Ic (~10...600 A);
2. Welding voltage 1)s (-10...30 V);
3. Welding speed Vc (-1.5...15 mm/s), (-5.4...54 m/h);
4. Diameter of non-consumable electrode d3H(~0.5...6.5 mm);
5. Installation arc length LDN (~1...5 mm);
6. Diameter of filler wire dnn (-2...6 mm);
7. Filler wire feed speed Vnn (-1.5...30 mm/s), (-5.4...108 m/h);
8. Shielding gas flow qr (~ 1... 12 l/min).
Based on the principle of argon welding and process parameters, the main functions of the equipment can be determined:
- supply of electrical energy to the arc and its regulation (lc, Uc);
- movement of the torch at the welding speed (Vc) and its regulation;
- supply of filler wire (Vnn) to the welding zone and regulation of its speed;
- supply of shielding gas (qr) to the welding zone and regulation of its flow;
- setting the arc length (Ld.u.) and corrective movements of the torch;
-arc initiation and crater filling;
- automatic tracking along the welding line, etc.
When starting the welding machine, the control circuit must ensure the following sequence of switching on parts and mechanisms of the equipment:
1) supply of protective gas (qr), preliminary purging of the gas supply system;
2) turning on the arc power source (Uxx.);
3) arc excitation (lc, Uc);
4) moving the machine at welding speed (Vc)
At the end of welding, the sequence of turning off systems and mechanisms should ensure crater welding and protection of the cooling seam:
Argon welding is most often performed in a production facility at a specially equipped workplace (welding station, installation, machine, RTK) and less often outside it. The welding station is equipped with local ventilation and is fenced with shields or screens to protect others from arc radiation.
The welding station for manual tungsten arc welding in argon (TIG) has:
- source of welding current of direct and/or alternating current;
- a burner or a set of burners for different currents;
- a device for initial arc initiation or for stabilizing an alternating current arc;
- control equipment for the welding cycle and gas protection;
a device for compensating or regulating the DC component of the welding current;

Welding materials

The inert gases argon and helium are used in combination with tungsten electrodes. When tungsten is exposed to oxygen, the latter is intensively oxidized and destroyed. Argon is predominantly used because it is cheaper than helium (argon is obtained from air), better protects the welding zone (heavier than air), and maintains a long (elastic) arc. A W-arc in helium has a higher temperature than an arc in argon, which makes it possible to weld thin aluminum (foil) using direct current of direct polarity. According to GOST 10157-79, argon gas is produced in the highest and first grades. Helium is supplied according to TU 51-689-75 grades A, B, and C.
Tungsten electrodes for arc welding are manufactured according to GOST 23949-80 in the form of rods with a length of 75-300 mm and a diameter of 0.5-10 mm. To increase the spatial stability of the arc and the permissible current (Fig. 4), activating additives of yttrium oxides (EVI-1, EVI-2, EVI-3 grades), lanthanum oxides (EVL grade), and less commonly thorium (EVT-15) are introduced into tungsten. Pure tungsten rods are produced under the EHF brand.

Fig.4

TIG welding is performed on butt, fillet, T and lap joints in various welding positions. Types of preparation of edges and seams for arc welding of steels and nickel-based alloys with non-consumable and consumable electrodes in shielding gases are regulated by GOST 14771-76. TIG welding according to the standard is recommended for thicknesses up to 20 mm, which is due to the low depth of metal penetration in one pass (up to 4 mm) and the low productivity of melting the additive and, consequently, filling the gap or cutting edges. Butt joints of steel up to 3-4 mm thick, and aluminum up to 5-6 mm thick are welded without bevelling the edges. TIG welding is often used when making root passes of small diameter pipes “in weight”.
Low-melting metals Mg, A1, Cu are recommended to be welded in the lower position. When welding refractory metals Mo, Nb, Zr, W, the thickness is limited to 2-3 mm. It is recommended to weld alloys based on Mg, Al, and Be using alternating current, so that during half-cycles of reverse polarity, cathodic cleaning of the weld pool from refractory oxide films occurs. It is recommended to weld other metals and alloys using direct current of direct polarity, since in this case there is minimal heating of the tungsten electrode and maximum penetration of the base metal.
The main welding modes for various metal thicknesses and wire diameters are given in Table 1.

Tab.1

Special welding methods

To expand the technological capabilities of TIG welding, special narrow-purpose welding methods have been developed to overcome the disadvantages of the standard method: low productivity, too wide seams, burn-throughs and increased warping when welding thin sheet metal, etc.
Welding AI, 77, alloy steels using fluoride flux allows you to increase the penetration depth and reduce the width of the seam, in addition, it improves the formation of the root passage, eliminates porosity and contamination with oxide films.
Submerged arc welding at currents up to 650 A allows you to weld metal up to 10-14 mm thick in one pass (high-alloy steels, aluminum, titanium).
Three-phase arc welding on alternating current (two phases are supplied to the tungsten electrodes, one to the product) ensures high stability of the arc without an oscillator, increases the power and melting capacity of a three-phase arc (up to 20 mm in one pass on AI).
Pulse-arc welding ensures the concentration of the thermal effect of the arc over time, which reduces the HAZ and deformation, and has a beneficial effect on crystallization and formation of a weld on thin metal (thickness 0.4-2 mm).
Welding with hot filler(current heating of the additive) combines the high quality of TIG welding and the productivity of MIG welding. Used for welding corrosion-resistant steels up to 50 mm thick.
Orbital welding of fixed pipe joints It is performed both with and without an additive, with and without electrode vibrations. The welding cycle is programmable. Backing rings are used to form a return roller, and if the pipe wall thickness is more than 3 mm, argon is blown in with forming pressure.
Magnetic field controlled arc welding, allows you to increase the welding speed, reduce the HAZ and achieve high quality weld formation. It is effective to use an arc rotated by a magnetic field when welding pipes to each other and to flanges, when welding pipes to tube sheets and other closed circuit joints. Tungsten or copper water-cooled electrodes are used. The movement of the arc causes a magnetic field transverse to the direction of welding. A magnetic field longitudinal to the electrode axis causes spatial stabilization of the arc column and its rotation.

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INTERSTATE STANDARD

TUNGSTEN ELECTRODES
WELDING NON-FUSED

TECHNICAL CONDITIONS

IPC PUBLISHING HOUSE OF STANDARDS

Moscow

INTERSTATE STANDARD

By Decree of the USSR State Committee on Standards dated January 18, 1980 No. 217, the introduction date was set

from 01.01.81

The validity period was lifted according to Protocol No. 4-93 of the Interstate Council for Standardization, Metrology and Certification (IUS 4-94)

This standard applies to electrodes made of pure tungsten and tungsten with activating additives (thorium dioxide, lanthanum and yttrium oxides), intended for arc welding with a non-consumable electrode in an environment of inert gases (argon, helium), as well as for plasma cutting, surfacing and spraying processes.

1. BRANDS

1.1. Depending on the chemical composition, electrodes should be made of tungsten grades indicated in table. 1.

Table 1

2. ASSORTMENT

2.1. The dimensions of the electrodes and maximum deviations must correspond to those indicated in the table. 2.

table 2

Nominal diameter	Maximum deviation
		At least 3000 in skeins
1,0; 1,6; 2,0; 2,5		75 ± 1; 150 ± 1;
3,0; 4,0; 5,0; 6,0; 8,0; 10,0		200 ± 2; 300 ± 2
1,0; 1,6; 2,0; 2,5; 3,0; 4,0		75 ± 1; 150 ± 1;
5,0; 6,0; 8,0; 10,0		200 ± 2; 300 ± 2
2,0; 3,0; 4,0; 5,0; 6,0		75 ± 1; 150 ± 1;
		200 ± 2; 300 ± 2
		75 ± 1; 150 ± 1;
5,0; 6,0; 8,0; 10,0		200 ± 2; 300 ± 2
2,0; 3,0; 4,0; 5,0;		75 ± 1; 150 ± 1;
		200 ± 2; 300 ± 2

An example of a symbol for an EVL electrode, 2.0 mm in diameter, 150 mm in length:

Tungsten electrode EVL-Æ 2-150 - GOST 23949-80

3. TECHNICAL REQUIREMENTS

3.1. Tungsten electrodes must be manufactured in accordance with the requirements of this standard from grades of pure tungsten and tungsten with activating additives, the chemical composition of which corresponds to that specified in table. 3.

Table 3

Electrode brand	Mass fraction, %
	Tungsten, no less	Additives			Impurities, no more
	Tungsten, no less	Lanthanum oxide	Yttrium oxide	Thorium dioxide	Aluminum, iron, nickel, silicon, calcium, molybdenum (total)

Notes:

1. The mass fractions of lanthanum oxide, yttrium oxide, thorium dioxide and tantalum indicated in the table are included in the mass fraction of tungsten.

2. For the EVL brand, nickel is not included in the amount of impurities.

3.2. The surface of the electrodes should be free of cavities, delaminations, cracks, oxides, residues of process lubricants, foreign inclusions and contaminants.

On the surface of the electrodes processed by centerless grinding to the sizes indicated in table. 2, transverse risks from grinding with a depth of more than half the maximum deviation per diameter are not allowed.

3.3. The surface of electrodes made by drawing must be cleaned of oxides, technological lubricants and other contaminants by chemical treatment (etching).

Drawing marks with a depth of more than half the diameter tolerance are not allowed on the surface of the electrodes.

3.4. The unevenness of the diameter along the length of the electrodes and ovality should not exceed the maximum deviations per diameter.

3.5. The electrodes must be straight. The non-straightness of the electrodes should not be more than 0.25% length.

3.6. The ends of the electrodes must have a straight cut. Chips greater than the maximum deviation per diameter are not allowed on the end cut of the electrodes.

3.7. Internal delaminations and cracks are not allowed.

4. ACCEPTANCE RULES

4.1. Electrodes are accepted in batches. The batch must consist of electrodes made from a charge of the same preparation, and must be documented in one quality document.

The quality document must contain:

name of the manufacturer and trademark of the manufacturer;

name and brand of the product;

batch number;

chemical analysis result;

date of manufacture;

the mass of the party and the number of seats in the party;

designation of the standard.

The quality document is placed in box No. 1.

The batch weight should not exceed 1300 kg.

4.2. To determine the activating additives, three to five welded or sintered rods are selected from each batch.

The determination of impurities is carried out by the manufacturer on each batch of tungsten powder on a sample in accordance with GOST 20559-75.

4.3. Checking the compliance of the electrodes with paragraphs. 2.1, 3.2 - 3.7 are carried out on each electrode.

4.4. If unsatisfactory results are obtained regarding the chemical composition, repeated tests are carried out on it on a double sample taken from the same batch. The results of repeated tests apply to the entire batch.

5. TEST METHODS

5.1. Sampling and preparation

5.1.1. To determine the activating additives, three to five rods are taken from the sample, pieces weighing 30–50 g are beaten off and they are ground in a mechanical mortar. The resulting powder is subjected to magnetic separation.

5.3. Geometric dimensions, uniformity of diameter along the length and ovality of the electrodes are checked with a micrometer according to GOST 6507-90 or a caliper according to GOST 166-89, as well as a ruler according to GOST 427-75.

5.4. The quality of the electrode surface is checked visually. In case of disagreement in quality assessment, optical means and measuring instruments are used.

5.5. The straightness of the electrodes is checked using a probe according to TU 2-034-225-87 on a flat metal plate in accordance with GOST 10905-86.

5.6. The absence of internal delaminations and cracks is checked using an eddy current flaw detector.

6. LABELING, PACKAGING, TRANSPORTATION AND STORAGE

6.1. Each electrode must be marked in accordance with table. 4.

Electrodes with a diameter of 3.0 mm or more can be marked by chamfering 1 mm × 45° or notches.

The marking must be applied to one end of the electrode.

The marking can be applied to the end in the form of a strip or a dot on the surface at the end over a length of 5 - 10 mm.

6.2. Electrodes of the same brand and diameter must be placed in cardboard boxes with foam, corrugated or pressed thick paper trays.

6.3. Each box of electrodes is affixed with a label containing:

name of the manufacturer or its trademark;

Product name;

product designation;

quantity, pcs.;

batch number;

release date;

type of marking;

technical control stamp.

6.4. Boxes with electrodes are packed in wooden boxes in accordance with GOST 2991-85 type 1 or 2, lined inside with waterproof packaging paper in accordance with GOST 8828-89. The remaining free volume of the box is tightly filled with packaging paper or cotton wool in accordance with GOST 5679-91.

The gross weight of the box is no more than 40 kg.

6.5. The box is marked according to GOST 14192-96 with additional data:

names, brands, sizes of electrodes;

batch numbers;

packaging dates;

net weight.

6.6. Packed electrodes are transported by all types of transport in covered vehicles.

During transportation, the placement of boxes should prevent their movement, mechanical damage to the packaging and electrodes, and moisture ingress.

Transportation conditions in terms of exposure to climatic factors - according to group Zh GOST 15150-69.

6.7. The electrodes should be stored in the packaging specified in clause 6.4, according to the storage conditions group L GOST 15150-69.

APPLICATION
Mandatory

1. METHOD FOR DETERMINING LANTHANUM OXIDE CONTENT

The method establishes the determination of lanthanum oxide in lanthanum welded tungsten rods and electrodes.

1.1. Essence of the method

The method is based on the separation of lanthanum from tungsten by dissolving a pre-oxidized and calcined test sample to tungsten anhydride (WO 3) in a solution of sodium carbonate.

In this case, lanthanum, present in tungsten in the form of La 2 O 3 , precipitates, and the soluble form of lanthanum is additionally precipitated with ammonia in the form of La(OH) 3 .

The precipitate is filtered off, dissolved in hydrochloric acid, and all the lanthanum is again precipitated with ammonia in the form of La(OH) 3 , which is filtered, washed and calcined to La 2 O 3 .

The error of the method with a mass fraction of lanthanum oxide from 1% to 3% is 0.1% with a mass fraction of lanthanum oxide less than 1% - 0.05%.

1.2. Reagents

Crystalline sodium carbonate according to GOST 84-76, 30% solution.

1.3. Sample preparation

Tungsten anhydride is pre-calcined in a muffle furnace at 700 - 750 °C for 1.5 - 2 hours.

Tungsten powder, a sample from a rod or electrode, is oxidized to anhydride by calcination in a muffle furnace at a temperature of 700 - 750 °C. In this case, the sample is poured into a porcelain crucible at 1/3 of its height and placed in a muffle at 400 - 500 ° C for 1.5 - 2 hours, and then the temperature is raised to 700 - 750 ° C and the crucible is kept until the powder is completely oxidized (~ 3 hours).

To ensure uniform oxidation of tungsten, the crucible is removed from the furnace two or three times and the sample is mixed.

1.4. Carrying out analysis

2 - 3 g of tungsten anhydride are placed in a glass of 150 - 200 cm 3, 50 - 70 cm 3 of sodium carbonate solution is added and dissolved when heated.

After dissolving tungsten anhydride, the solution is diluted with distilled water to a volume of ~100 cm 3, 20-30 cm of ammonia solution is added, the glass is placed in an electric bath and the precipitate is allowed to coagulate. The precipitate is filtered through a “white tape” filter with an adsorbent, washed with a warm 5% ammonia solution; the filter with the sediment is placed in the glass in which the precipitation was carried out, 15 - 20 cm 3 of hydrochloric acid is added and the contents of the glass are heated until the sediment is completely dissolved and the filter is mocerated.

The filtrate is neutralized with an ammonia solution using litmus, after which another 15 - 20 cm 3 of ammonia is added.

The precipitate of La(OH) 3 is allowed to coagulate, then it is filtered through a “white tape” filter with an adsorbent. The precipitate is washed with hot water, to which a few drops of ammonia solution are added until the reaction for Cl is negative (test with AgNO 3 and HNO 3).

The washed precipitate with a filter is placed in a pre-calcined and weighed porcelain crucible, ashed and calcined in a muffle furnace at a temperature of 700 - 750 ° C to constant weight.

1.5. Processing the results

The mass fraction of lanthanum oxide in percent is calculated using the formula

Where T - sediment mass, g;

m 1 - mass of tungsten anhydride (WO 3) sample, g;

0.7931 - conversion factor from tungsten anhydride to tungsten.

Note. The calcined precipitate of lanthanum oxide contains iron oxide, the amount of which is very small compared to the amount of lanthanum oxide, so the mass of iron oxide can be neglected.

If the determination of pure lanthanum oxide is required, then the calcined precipitate is dissolved in hydrochloric acid, the iron is colorimetered, and the mass of lanthanum oxide is determined from the difference.

2. METHOD FOR DETERMINING YTTRIUM OXIDE CONTENT

The method establishes the determination of yttrium oxide in yttriated welded tungsten rods and electrodes.

2.1. Essence of the method

The method is based on the separation of yttrium from tungsten by dissolving the test sample in hydrofluoric acid with the addition of nitric acid.

With a mass fraction of yttrium oxide from 1 to 3%, the error of the method is 4 - 5%.

2.2. Equipment, reagents and solutions

Drying cabinet providing heating to a temperature of (150 ± 50) °C.

A muffle furnace with a thermocouple providing heating to a temperature of (1100 ± 50) °C.

Laboratory porcelain glassware - GOST 9147-80 ..

2.3. Sample preparation

Samples of yttriated tungsten are cleaned of possible contamination by washing them several times with alcohol and subsequent drying in an oven at a temperature of 50 - 70 °C for 10 minutes. Prepared samples are stored in glass bottles or test tubes with ground stoppers.

2.4. Carrying out analysis

A sample weighing 1 g is placed in a platinum cup with a capacity of 100 cm 3, 25 - 30 cm 3 of hydrofluoric acid is added and nitric acid is carefully added dropwise until the metal dissolves.

After the tungsten has completely dissolved and the release of nitrogen oxides has stopped, 30 cm 3 of water heated to a temperature of 80 - 90 ° C is added to the cup.

The solution with the precipitate is allowed to stand for 1 hour, after which it is filtered through a polyethylene funnel.

After transferring the sediment to the filter, the bottom of the cup is wiped with a piece of wet filter and all the contents on it are poured onto the filter with hot water. Then the precipitate is washed five to six times with a hot ammonia solution (60 - 70 ° C) and another two to three times with hot water.

The washed sediment is transferred to a pre-weighed porcelain crucible, dried in an oven at a temperature of 100 - 150 ° C, and then calcined in a muffle furnace at a temperature of 650 - 700 ° C to constant weight and weighed in the form of yttrium oxide.

2.5. Processing the results

The mass fraction of yttrium oxide in percent is calculated using the formula

Where m- mass of calcined residue, g;

T 1 - weight of sample sample, g.

3. METHOD FOR DETERMINING THE CONTENT OF THORIUM DIOXIDE

The method establishes the determination of thorium dioxide in thoriated welded tungsten rods and electrodes.

3.1. Essence of the method

The method is based on the formation of a ThF 4 ·4H 2 O precipitate when a sample is dissolved in a mixture of hydrofluoric and nitric acids.

The error of the method at a mass fraction of thorium dioxide from 1.5% to 2% is 0.1%.

3.2. Reagents

Hydrofluoric acid (fluoric acid) - GOST 10484-78.

3.3. Sample preparation

The samples are boiled for several minutes in an alkali solution until oxides are completely removed from the surface, washed in distilled water and dried in an oven.

3.4. Carrying out analysis

A sample weighing 1 - 2 g is placed in a platinum cup with a capacity of 100 cm 3, 25 - 30 cm 3 of hydrofluoric acid is added and nitric acid is carefully added dropwise.

After the tungsten has completely dissolved and the release of nitrogen oxides has stopped, 30 cm 3 of hot water is added to the cup. The solution containing the thorium oxide precipitate is allowed to stand for 1 hour, after which it is filtered through a rubber, vinyl plastic or platinum funnel.

Before filtering, a small amount of adsorbent is placed on the filter.

After transferring the sediment to the filter, wipe the bottom of the cup with a piece of wet filter and rinse the cup with hot water. When the thorium oxide precipitate is completely transferred to the filter, it is washed several times with hot water, and then five to six times with a hot ammonia solution and another two to three times with hot water.

The wet filter is transferred to a porcelain or platinum crucible pre-weighed to constant weight, ashed, calcined at a temperature of 750 - 800 ° C and weighed.

At the same time, a control experiment is carried out with all reagents.

3.5. Processing the results

The mass fraction of thorium dioxide in percent is calculated using the formula

Where m- mass of ThO 2 sediment, g;

m 1 - mass of sediment in the control experiment, g;

m 2 - weight of the sample, g.

STATE STANDARD OF THE USSR UNION

TUNGSTEN ELECTRODES
WELDING NON-FUSED

TECHNICAL CONDITIONS

GOST 23949-80

USSR STATE COMMITTEE ON STANDARDS

Moscow

STATE STANDARD OF THE USSR UNION

By Decree of the USSR State Committee on Standards dated January 18, 1980 No. 217, the introduction date was established

from 01.01.81

By Decree of the USSR State Standard dated July 22, 1986 No. 2200, the validity period was extended

until 01/01/90

1. BRANDS

1.1 . Depending on the chemical composition, electrodes should be made of tungsten grades indicated in table. .

Table 1

Brand	OKP code	Material
EHF	1853741000	Tungsten pure
EVL	1853742000	Tungsten with lanthanum oxide additive
EVI-1	1853743000
EVI-2	1853744000	Tungsten with yttrium oxide additive
EVI-3	1853745000	Tungsten with yttrium oxide additive
EVT-15	1853746000	Tungsten with thorium dioxide additive

2. ASSORTMENT

2.1 . The dimensions of the electrodes and maximum deviations must correspond to those indicated in the table. .

Table 2

Brand	Nominal diameter	Maximum deviation	Length
EHF		±0.2	At least 3000 in skeins
	1,0; 1,6; 2,0; 2,5	±0.1	75 ± 1; 150 ± 1;
	3,0; 4,0; 5,0; 6,0; 8,0; 10,0	±0.2	200 ± 2; 300 ± 2
EVL	1,0; 1,6; 2,0; 2,5; 3,0; 4,0;	±0.1	75 ± 1; 150 ± 1;
EVL	5,0; 6,0; 8,0; 10,0	±0.2	200 ± 2; 300 ± 2
EVI-1	2,0; 3,0; 4,0; 5,0; 6,0	±0.1	75 ± 1; 150 ± 1
EVI-1	8,0; 10,0	±0.2	200 ± 2; 300 ± 2
EVI-2	2,0; 3,0; 4,0; 5,0; 6,0; 8,0; 10,0	±0.15
EVI-3	2,0; 3,0; 4,0; 5,0; 6,0; 8,0; 10,0	±0.15
EVT-15	2,0; 3,0; 4,0; 5,0 6,0; 8,0; 10,0	±0.15	75 ± 1; 150 ± 1; 200 ± 2; 300 ± 2

Example of a symbolelectrode brand EVL, diameter 2.0 mm, length 150 mm:

Tungsten electrode EVL- Æ 2-150 - GOST 23949-80

3. TECHNICAL REQUIREMENTS

3.1 . Tungsten electrodes must be manufactured in accordance with the requirements of this standard from grades of pure tungsten and tungsten with activating additives, the chemical composition of which corresponds to that specified in table. .

3.2 . The surface of the electrodes should be free of cavities, delaminations, cracks, oxides, residues of process lubricants, foreign inclusions and contaminants.

On the surface of the electrodes processed by centerless grinding to the sizes indicated in table. , transverse risks from grinding with a depth of more than half the maximum deviation per diameter are not allowed.

Table 3

Electrode brand	Mass fraction, %
	Tungsten, no less	Additives				Impurities, no more
	Tungsten, no less	Lanthanum oxide	Yttrium oxide	Thorium dioxide	Tantalum	Aluminum, iron, nickel, silicon, calcium, molybdenum (total)
EHF	99,92					0,08
EVL	99,95	1,1 - 1,4				0,05
EVI-1	99,89		1,5 - 2,3			0,11
EVI-2	99,95		2,0 - 3,0		0,01	0,05
EVI-3	99,95		2,5 - 3,5		0,01	0,05
EVT-15	99,91			1,5 - 2,0		0,09

Notes:

1 . The mass fractions of lanthanum oxide, yttrium oxide, thorium dioxide and tantalum indicated in the table are included in the mass fraction of tungsten.

2 . For the EVL brand, nickel is not included in the amount of impurities.

3.3 . The surface of electrodes made by drawing must be cleaned of oxides, technological lubricants and other contaminants by chemical treatment (etching).

Drawing marks with a depth of more than half the diameter tolerance are not allowed on the surface of the electrodes.

3.4 . The unevenness of the diameter along the length of the electrodes and ovality should not exceed the maximum deviations per diameter.

3.5 . The electrodes must be straight. The non-straightness of the electrodes should not be more than 0.25% of the length.

3.6 . The ends of the electrodes must have a straight cut. Chips greater than the maximum deviation per diameter are not allowed on the end cut of the electrodes.

3.7 . Internal delaminations and cracks are not allowed.

4. ACCEPTANCE RULES

4.1 . Electrodes are accepted in batches. The batch must consist of electrodes made from a charge of the same preparation, and must be documented in one quality document.

The quality document must contain:

name of the manufacturer and trademark of the manufacturer;

name and brand of the product;

batch number;

chemical analysis result;

date of manufacture;

the mass of the party and the number of seats in the party;

designation of the standard.

The quality document is placed in box No. 1.

The batch weight should not exceed 1300 kg.

4.2 . To determine activating additives, select 3 - 5 welded or sintered bars from each batch.

The determination of impurities is carried out by the manufacturer on each batch of tungsten powder on a sample in accordance with GOST 20559-75.

4.3 . Checking the compliance of the electrodes with paragraphs. , - carried out on each electrode.

4.4 . If unsatisfactory results are obtained regarding the chemical composition, repeated tests are carried out on it on a double sample taken from the same batch. The results of repeated tests apply to the entire batch.

5. TEST METHODS

5.1 . Sampling and preparation

5.1.1 . To determine the activating additives, 3-5 rods are taken from the sample, pieces weighing 30-50 g are beaten off and they are ground in a mechanical mortar.

The resulting powder is subjected to magnetic separation.

5.2 . The content of aluminum, iron, silicon, molybdenum, calcium, and nickel impurities is determined by GOST 14339.5 -82.

5.3 . The geometric dimensions, uniformity of diameter along the length and ovality of the electrodes are checked with a micrometer according to GOST 6507 -78, or with calipers according GOST 166 -80, as well as with a ruler GOST 427-75.

5.4 . The quality of the electrode surface is checked visually. In case of disagreement in quality assessment, optical means and measuring instruments are used.

5.5 . The straightness of the electrodes is checked using a probe in accordance with GOST 882-75 on a flat metal plate according to GOST 10905-86.

5.6 . The absence of internal delaminations and cracks is checked using an eddy current flaw detector.

6. LABELING, PACKAGING, TRANSPORTATION AND STORAGE

6.1 . Each electrode must be marked in accordance with table. .

Electrodes with a diameter of 3.0 mm or more can be marked by chamfering 1 mm´ 45° or notch.

The marking must be applied to one end of the electrode.

The marking can be applied to the end in the form of a strip or a dot on the surface at the end over a length of 5 - 10 mm.

Table 4

Brand	Color
EHF	Not marked
EVL	Black
EVI-1	Blue
EVI-2	Violet
EVI-3	Green
EVT-15	Red

6.2 . Electrodes of the same brand and diameter must be placed in cardboard boxes with foam, corrugated or pressed thick paper trays.

6.3 . Each box of electrodes is affixed with a label containing:

name of the manufacturer or its trademark;

Product name;

product designation;

quantity, pcs.;

batch number;

release date;

type of marking;

technical control stamp.

6.4 . Boxes with electrodes are packed in wooden boxes according to GOST 2991-85 type 1 or 2, lined inside with waterproof packaging paper according to GOST 8828 -75. The remaining free volume of the box is tightly filled with wrapping paper or cotton wool according to GOST 5679-85.

The gross weight of the box is no more than 40 kg.

6.5 . The box is marked according to GOST 14192-77 with additional data:

names, brands, sizes of electrodes;

batch numbers;

packaging dates;

net weight.

6.6 . Packed electrodes are transported by all types of transport in covered vehicles.

During transportation, the placement of boxes should prevent their movement, mechanical damage to the packaging and electrodes, and moisture ingress.

Transportation conditions in terms of exposure to climatic factors - according to group Zh GOST 15150-69.

6.7 . Electrodes should be stored in the packaging provided in paragraph. , according to the group of storage conditions L GOST 15150-69.

APPLICATION

Mandatory

1. METHOD FOR DETERMINING LANTHANUM OXIDE CONTENT

The method establishes the determination of lanthanum oxide in lanthanum welded tungsten rods and electrodes.

1.1 . Essence of the method

The method is based on the separation of lanthanum from tungsten by dissolving a previously oxidized and calcined test sample to tungsten anhydride ( WO 3 ) in a solution of sodium carbonate.

In this case, lanthanum, found in tungsten in the form La 2 O 3 , precipitates, and the soluble form of lanthanum is precipitated with ammonia in the form La(OH)3.

The precipitate is filtered off, dissolved in hydrochloric acid, and all the lanthanum is again precipitated with ammonia in the form La(OH ) 3, which is filtered, washed and calcined to La 2 O 3 .

The error of the method with a mass fraction of lanthanum oxide from 1% to 3% is 0.1%, with a mass fraction of lanthanum oxide less than 1% - 0.05%.

1.2 . Reagents

Crystalline sodium carbonate according to GOST 84-76, 30% solution.

Aqueous ammonia according to GOST 3760-79, 25% solution.

Hydrochloric acid according to GOST 3118-77, density 1.12 g/cm 3.

Distilled water according to GOST 6709-72.

1.3 . Sample preparation

Tungsten anhydride is pre-calcined in a muffle furnace at 700 - 750 °C for 1.5 - 2 hours.

To ensure uniform oxidation of tungsten, the crucible is removed from the furnace 2-3 times and the sample is mixed.

1.4 . Carrying out analysis

2 - 3 g of tungsten anhydride is placed in a 150-200 ml glass, 50-70 ml of sodium carbonate solution is added and dissolved with heating.

After dissolving the tungsten anhydride, the solution is diluted with distilled water to a volume of ~ 100 ml, 20 - 30 ml of ammonia solution is added, the glass is placed in an electric bath and the precipitate is allowed to coagulate. The precipitate is filtered through a “white tape” filter with an adsorbent, washed with a warm 5% ammonia solution; the filter with the sediment is placed in the glass in which the sedimentation was carried out, 15 - 20 ml of hydrochloric acid are added and the contents of the glass are heated until the sediment is completely dissolved and the filter is mocerated.

The filtrate is neutralized with an ammonia solution using litmus, after which another 15 - 20 ml of ammonia is added.

Precipitate La(OH ) 3 is allowed to coagulate, then it is filtered through a “white tape” filter with an adsorbent. The precipitate is washed with hot water, to which a few drops of ammonia solution are added until the reaction is negative. Cl (sample with AgNO 3 and H N O 3).

The washed precipitate with a filter is placed in a pre-calcined and weighed porcelain crucible, ashed and calcined in a muffle furnace at a temperature of 700 - 750 ° C to constant weight.

1.5 . Processing the results

The mass fraction of lanthanum oxide in percent is calculated using the formula

Where T- sediment mass, g;

t 1- mass of tungsten anhydride sample ( WO 3 ), g;

0 .7931 is the conversion factor from tungsten anhydride to tungsten.

Note . The calcined precipitate of lanthanum oxide contains iron oxide, the amount of which is very small compared to the amount of lanthanum oxide, so the mass of iron oxide can be neglected.

2. METHOD FOR DETERMINING YTTRIUM OXIDE CONTENT

The method establishes the determination of yttrium oxide in iterated welded tungsten rods and electrodes.

2.1 . Essence of the method

The method is based on the separation of yttrium from tungsten by dissolving the test sample in hydrofluoric acid with the addition of nitric acid.

With a mass fraction of yttrium oxide from 1 to 3%, the error of the method is 4 - 5%.

2.2 . Equipment, reagents and solutions

Drying cabinet providing heating to a temperature of (150 ± 50) °C. A muffle furnace with a thermocouple providing heating to a temperature of (1100 ± 50) °C.

Platinum cups and crucibles - GOST 6563-75.

Samples of yttriated tungsten are cleaned of possible contamination by washing them several times with alcohol and subsequent drying in an oven at a temperature of 50 - 70° C for 10 min.

Prepared samples are stored in glass bottles or test tubes with ground stoppers.

2.4 . Carrying out analysis

A sample weighing 1 g is placed in a platinum cup with a capacity of 100 ml, 25 - 30 ml of hydrofluoric acid are added and nitric acid is carefully added dropwise until the metal dissolves.

After the tungsten has completely dissolved and the release of nitrogen oxides has stopped, 30 ml of water heated to a temperature of 80 - 90 ° C is added to the cup.

The solution with the precipitate is allowed to stand for 1 hour, after which it is filtered through a polyethylene funnel.

After transferring the sediment to the filter, the bottom of the cup is wiped with a piece of wet filter and all the contents on it are poured onto the filter with hot water. Then the precipitate is washed 5 - 6 times with a hot ammonia solution (60 - 70 ° C) and another 2 - 3 times with hot water.

2.5 . Processing the results

The mass fraction of yttrium oxide in percent is calculated using the formula

where m - mass of calcined residue, g;

m 1 - weight of the sample, g.

3. METHOD FOR DETERMINING THE CONTENT OF THORIUM DIOXIDE

The method establishes the determination of thorium dioxide in thoriated welded tungsten rods and electrodes.

3.1 . Essence of the method

The method is based on the formation of precipitate T hF 4 × 4 H 2 O when the sample is dissolved in a mixture of hydrofluoric and nitric acids.

The error of the method at a mass fraction of thorium dioxide from 1.5% to 2% is 0.1%.

3.2 . Reagents

Hydrofluoric acid (fluoric acid) - GOST 10484-78.

Nitric acid according to GOST 4461-77.

Aqueous ammonia according to GOST 3760-79, diluted 1:1.

Distilled water according to GOST 6709-72.

3.3 . Sample preparation

The samples are boiled for several minutes in an alkali solution until oxides are completely removed from the surface, washed in distilled water and dried in an oven.

3.4 . Carrying out analysis

A sample weighing 1 - 2 g is placed in a platinum cup with a capacity of 100 ml, 25 - 30 ml of hydrofluoric acid is added and nitric acid is carefully added dropwise.

After the tungsten has completely dissolved and the release of nitrogen oxides has stopped, 30 ml of hot water is added to the cup. A solution with a precipitate of thorium oxideallow to stand for 1 hour, then filter through a rubber, vinyl plastic or platinum funnel.

Before filtering, a small amount of adsorbent is placed on the filter.

After transferring the sediment to the filter, wipe the bottom of the cup with a piece of wet filter and rinse the cup with hot water. When the thorium oxide precipitate is completely transferred to the filter, it is washed several times with hot water, and then 5 - 6 times with a hot ammonia solution and another 2 - 3 times with hot water.

The wet filter is transferred to a porcelain or platinum crucible pre-weighed to constant weight, ashed, calcined at a temperature of 750 - 800 ° C and weighed.

At the same time, a control experiment is carried out with all reagents.

3.5 . Processing the results

The mass fraction of thorium dioxide in percent is calculated using the formula

Where T- sediment mass T hO 2, g;

t 1- mass of sediment in the control experiment, g;

t 2- weight of the sample, g.

The standard applies to electrodes made of pure tungsten and tungsten with activating additives (thorium dioxide, lanthanum and yttrium oxides), intended for arc welding with a non-consumable electrode in an environment of inert gases (argon, helium), as well as for flame cutting processes, surfacing and spraying/

Designation:	GOST 23949-80
Russian name:	Tungsten welding electrodes, non-consumable. Specifications
Status:	valid
Date of text update:	05.05.2017
Date added to the database:	01.09.2013
Effective date:	01.01.1981
Approved:	01/18/1980 Gosstandart of the USSR (USSR Gosstandart 217)
Published:	Standards Publishing House (1980) IPC Standards Publishing House (2004)
Download links:

GOST 23949-80

INTERSTATE STANDARD

TUNGSTEN ELECTRODES
WELDING NON-FUSED

TECHNICAL CONDITIONS

IPC PUBLISHING HOUSE OF STANDARDS

Moscow

INTERSTATE STANDARD

By Decree of the USSR State Committee on Standards dated January 18, 1980 No. 217, the introduction date was set

from 01.01.81

The validity period was lifted according to Protocol No. 4-93 of the Interstate Council for standardization, metrology and certification(IUS 4-94)

1. BRANDS

1.1. Depending on the chemical composition, electrodes should be made of tungsten grades indicated in table. .

Table 1

	OKP code	Material
		Tungsten pure
		Tungsten with lanthanum oxide additive



		Tungsten with thorium dioxide additive

2. ASSORTMENT

Nominal diameter

Maximum deviation

At least 3000 in skeins

1,0; 1,6; 2,0; 2,5

75 ± 1; 150 ± 1;

3,0; 4,0; 5,0; 6,0; 8,0; 10,0

200 ± 2; 300 ± 2

1,0; 1,6; 2,0; 2,5; 3,0; 4,0

75 ± 1; 150 ± 1;

5,0; 6,0; 8,0; 10,0

200 ± 2; 300 ± 2

2,0; 3,0; 4,0; 5,0; 6,0

75 ± 1; 150 ± 1;

200 ± 2; 300 ± 2

75 ± 1; 150 ± 1;

5,0; 6,0; 8,0; 10,0

200 ± 2; 300 ± 2

2,0; 3,0; 4,0; 5,0;

75 ± 1; 150 ± 1;

200 ± 2; 300 ± 2

Example of a symbolelectrode brand EVL, diameter 2.0 mm, length 150 mm:

Tungsten electrode EVL- Æ 2-150 - GOST 23949-80

3. TECHNICAL REQUIREMENTS

Table 3

3.3. The surface of electrodes made by drawing must be cleaned of oxides, technological lubricants and other contaminants by chemical treatment (etching).

Drawing marks with a depth of more than half the diameter tolerance are not allowed on the surface of the electrodes.

3.4. The unevenness of the diameter along the length of the electrodes and ovality should not exceed the maximum deviations per diameter.

3.5. The electrodes must be straight. The non-straightness of the electrodes should not be more than 0.25% length.

3.6. The ends of the electrodes must have a straight cut. Chips greater than the maximum deviation per diameter are not allowed on the end cut of the electrodes.

4. ACCEPTANCE RULES

4.1. Electrodes are accepted in batches. The batch must consist of electrodes made from a charge of the same preparation, and must be documented in one quality document.

The quality document must contain:

name of the manufacturer and trademark of the manufacturer;

name and brand of the product;

batch number;

chemical analysis result;

date of manufacture;

the mass of the party and the number of seats in the party;

designation of the standard.

The quality document is placed in box No. 1.

The batch weight should not exceed 1300 kg.

4.2. To determine the activating additives, three to five welded or sintered rods are selected from each batch.

The determination of impurities is carried out by the manufacturer on each batch of tungsten powder on a sample in accordance with GOST 20559-75.

4.3. Checking the compliance of the electrodes with paragraphs. , - carried out on each electrode.

5. TEST METHODS

5.1. Sampling and preparation

5.2. The content of aluminum, iron, silicon, molybdenum, calcium, and nickel impurities is determined according to GOST 14339.5-91.

5.4. The quality of the electrode surface is checked visually. In case of disagreement in quality assessment, optical means and measuring instruments are used.

5.5. The straightness of the electrodes is checked using a probe according to TU 2-034-225-87 on a flat metal plate in accordance with GOST 10905-86.

5.6. The absence of internal delaminations and cracks is checked using an eddy current flaw detector.

6. LABELING, PACKAGING, TRANSPORTATION AND STORAGE

6.1. Each electrode must be marked in accordance with table. .

Electrodes with a diameter of 3.0 mm or more can be marked by chamfering 1 mm × 45° or notches.

The marking must be applied to one end of the electrode.

The marking can be applied to the end in the form of a strip or a dot on the surface at the end over a length of 5 - 10 mm.

Table 4

6.2. Electrodes of the same brand and diameter must be placed in cardboard boxes with foam, corrugated or pressed thick paper trays.

6.3. Each box of electrodes is affixed with a label containing:

name of the manufacturer or its trademark;

Product name;

product designation;

quantity, pcs.;

batch number;

release date;

type of marking;

technical control stamp.

The method establishes the determination of lanthanum oxide in lanthanum welded tungsten rods and electrodes.

1.1. Essence of the method

The method is based on the separation of lanthanum from tungsten by dissolving a previously oxidized and calcined test sample to tungsten anhydride ( WO 3 ) in a solution of sodium carbonate.

In this case, lanthanum, located in tungsten in the form of La 2 O 3 , precipitates, and the soluble form of lanthanum is additionally precipitated with ammonia in the form of La(OH) 3 .

The precipitate is filtered off, dissolved in hydrochloric acid, and all the lanthanum is again precipitated with ammonia in the form of La(OH) 3, which is filtered, washed and calcined to La 2 O 3 .

The error of the method with a mass fraction of lanthanum oxide from 1% to 3% is 0.1% with a mass fraction of lanthanum oxide less than 1% - 0.05%.

1.2. Reagents

Crystalline sodium carbonate according to GOST 84-76, 30% solution.

Aqueous ammonia according to GOST 3760-79, 25% solution.

Hydrochloric acid according to GOST 3118-77, density 1.12 g/cm 3.

1.3. Sample preparation

Tungsten anhydride is pre-calcined in a muffle furnace at 700 - 750 °C for 1.5 - 2 hours.

To ensure uniform oxidation of tungsten, the crucible is removed from the furnace two or three times and the sample is mixed.

1.4. Carrying out analysis

2 - 3 g of tungsten anhydride are placed in a glass of 150 - 200 cm 3, 50 - 70 cm 3 of sodium carbonate solution is added and dissolved when heated.

The filtrate is neutralized with an ammonia solution using litmus, after which another 15 - 20 cm 3 of ammonia is added.

The washed precipitate with a filter is placed in a pre-calcined and weighed porcelain crucible, ashed and calcined in a muffle furnace at a temperature of 700 - 750 ° C to constant weight.

1.5. Processing the results

The mass fraction of lanthanum oxide in percent is calculated using the formula

Where T - sediment mass, g;

m 1 - weight of a sample of tungsten anhydride (WO 3 ), g;

0.7931 - conversion factor from tungsten anhydride to tungsten.

Note: The calcined precipitate of lanthanum oxide contains iron oxide, the amount of which is very small compared to the amount of lanthanum oxide, so the mass of iron oxide can be neglected.

2. METHOD FOR DETERMINING YTTRIUM OXIDE CONTENT

The method establishes the determination of yttrium oxide in yttriated welded tungsten rods and electrodes.

2.1. Essence of the method

The method is based on the separation of yttrium from tungsten by dissolving the test sample in hydrofluoric acid with the addition of nitric acid.

With a mass fraction of yttrium oxide from 1 to 3%, the error of the method is 4 - 5%.

2.2. Equipment, reagents and solutions

Drying cabinet providing heating to a temperature of (150 ± 50) °C.

Muffle furnace with a thermocouple, providing heating to a temperature of (1100 ± 50)° C.

Platinum cups and crucibles - GOST 6563-75.

Laboratory porcelain glassware - GOST 9147-80.

Hydrofluoric acid (hydrofluoric acid) - according to GOST 10484-78.

Nitric acid - GOST 4461-77.

Aqueous ammonia - GOST 3760-79, diluted 1:1.

Polyethylene funnels.

Distilled water - GOST 6709-72.

Rectified ethyl alcohol - GOST 5962-67*.

* GOST R 51652-2000 is in force on the territory of the Russian Federation.

Laboratory filter paper - GOST 12026-76.

2.3. Sample preparation

2.4. Carrying out analysis

A sample weighing 1 g is placed in a platinum cup with a capacity of 100 cm 3, 25 - 30 cm 3 of hydrofluoric acid is added and nitric acid is carefully added dropwise until the metal dissolves.

After the tungsten has completely dissolved and the release of nitrogen oxides has stopped, 30 cm 3 of water heated to a temperature of 80 - 90 ° C is added to the cup.

The solution with the precipitate is allowed to stand for 1 hour, after which it is filtered through a polyethylene funnel.

2.5. Processing the results

The mass fraction of yttrium oxide in percent is calculated using the formula

Where m- mass of calcined residue, g;

T 1 - weight of sample sample, g.

3. METHOD FOR DETERMINING THE CONTENT OF THORIUM DIOXIDE

The method establishes the determination of thorium dioxide in thoriated welded tungsten rods and electrodes.

3.1. Essence of the method

The method is based on the formation of ThF precipitate 4 4H 2 O when the sample is dissolved in a mixture of hydrofluoric and nitric acids.

The error of the method at a mass fraction of thorium dioxide from 1.5% to 2% is 0.1%.

3.2. Reagents

Hydrofluoric acid (fluoric acid) - GOST 10484-78.

Nitric acid according to GOST 4461-77.

Aqueous ammonia according to GOST 3760-79, diluted 1:1.

Distilled water according to GOST 6709-72.

3.3. Sample preparation

The samples are boiled for several minutes in an alkali solution until oxides are completely removed from the surface, washed in distilled water and dried in an oven.

3.4. Carrying out analysis

A sample weighing 1 - 2 g is placed in a platinum cup with a capacity of 100 cm 3, 25 - 30 cm 3 of hydrofluoric acid is added and nitric acid is carefully added dropwise.

Before filtering, a small amount of adsorbent is placed on the filter.

The wet filter is transferred to a porcelain or platinum crucible pre-weighed to constant weight, ashed, calcined at a temperature of 750 - 800 ° C and weighed.

At the same time, a control experiment is carried out with all reagents.

3.5. Processing the results

The mass fraction of thorium dioxide in percent is calculated using the formula

Where m- mass of ThO 2 sediment, g;

m 1 - mass of sediment in the control experiment, g;

m 2 - weight of the sample, g.

INTERSTATE STANDARD

TECHNICAL CONDITIONS

Official publication

IPC PUBLISHING HOUSE OF STANDARDS Moscow

INTERSTATE STANDARD

TUNGSTEN WELDING ELECTRODES, NON-CONSUMING

Specifications

Welding nonconsumable tungsten electrodes. Specifications

GOST

23949-80

MKS 25.160.20 OKP 18 5374 0000

By Decree of the USSR State Committee on Standards dated January 18, 1980 No. 217, the introduction date was set

The validity period was lifted according to Protocol No. 4-93 of the Interstate Council for Standardization, Metrology and Certification (IUS 4-94)

1.1. Depending on the chemical composition, electrodes should be made of tungsten grades indicated in table. 1.

Table 1

2. ASSORTMENT

2.1. The dimensions of the electrodes and maximum deviations must correspond to those indicated in the table. 2.

Official publication

Reproduction is prohibited

★

Reissue. September 2004

Table 2 mm

Nominal diameter	Limit deviation
		At least 3000 in skeins
1,0; 1,6; 2,0; 2,5
3,0; 4,0; 5,0; 6,0; 8,0; 10,0
1,0; 1,6; 2,0; 2,5; 3,0; 4,0
5,0; 6,0; 8,0; 10,0
5,0; 6,0; 8,0; 10,0
2,0; 3,0; 4,0; 5,0; 6,0



5,0; 6,0; 8,0; 10,0
2,0; 3,0; 4,0; 5,0; 6,0; 8,0; 10,0		75±1; 150±1; 200±2; 300±2

An example of a symbol for an EVL electrode, 2.0 mm in diameter, 150 mm in length:

Tungsten electrode EVL-0 2-150 - GOST 23949-80

3. TECHNICAL REQUIREMENTS

Table 3

Notes:

1. The mass fractions of lanthanum oxide, yttrium oxide, thorium dioxide and tantalum indicated in the table are included in the mass fraction of tungsten.

2. For the EVL brand, nickel is not included in the amount of impurities.

3.2. The surface of the electrodes should be free of cavities, delaminations, cracks, oxides, residues of process lubricants, foreign inclusions and contaminants.

3.3. The surface of electrodes made by drawing must be cleaned of oxides, technological lubricants and other contaminants by chemical treatment (etching).

Drawing marks with a depth of more than half the diameter tolerance are not allowed on the surface of the electrodes.

3.4. The unevenness of the diameter along the length of the electrodes and ovality should not exceed the maximum deviations per diameter.

3.5. The electrodes must be straight. The non-straightness of the electrodes should not be more than 0.25% of the length.

3.6. The ends of the electrodes must have a straight cut. Chips greater than the maximum deviation per diameter are not allowed on the end cut of the electrodes.

3.7. Internal delaminations and cracks are not allowed.

4. ACCEPTANCE RULES

4.1. Electrodes are accepted in batches. The batch must consist of electrodes made from a charge of the same preparation, and must be documented in one quality document.

The quality document must contain:

name of the manufacturer and trademark of the manufacturer;

name and brand of the product;

batch number;

chemical analysis result;

date of manufacture;

the mass of the party and the number of seats in the party;

designation of the standard.

The quality document is placed in box No. 1.

The batch weight should not exceed 1300 kg.

4.2. To determine the activating additives, three to five welded or sintered rods are selected from each batch.

The determination of impurities is carried out by the manufacturer on each batch of tungsten powder on a sample in accordance with GOST 20559-75.

4.3. Checking the compliance of the electrodes with paragraphs. 2.1, 3.2-3.7 are carried out on each electrode.

5. TEST METHODS

5.1. Sampling and preparation

5.1.1. To determine the activating additives, three to five rods are selected from the sample, pieces weighing 30-50 g are beaten off and they are ground in a mechanical mortar.

The resulting powder is subjected to magnetic separation.

5.3. Geometric dimensions, uniformity of diameter along the length and ovality of the electrodes are checked with a micrometer in accordance with GOST 6507-90 or with a caliper in accordance with GOST 166-89, as well as with a ruler in accordance with GOST 427-75.

5.4. The quality of the electrode surface is checked visually. In case of disagreement in quality assessment, optical means and measuring instruments are used.

5.5. The straightness of the electrodes is checked using a probe according to TU 2-034-225-87 on a flat metal plate in accordance with GOST 10905-86.

5.6. The absence of internal delaminations and cracks is checked using an eddy current flaw detector.

6. LABELING, PACKAGING, TRANSPORTATION AND STORAGE

6.1. Each electrode must be marked in accordance with table. 4.

Electrodes with a diameter of 3.0 mm or more can be marked by chamfering 1 mm x 45° or notches.

The marking must be applied to one end of the electrode.

The marking can be applied to the end in the form of a strip or a dot on the surface at the end at a length of 5-10 mm.

6.2. Electrodes of the same brand and diameter must be placed in cardboard boxes with foam, corrugated or pressed thick paper trays.

6.3. Each box with electrodes is labeled with a label containing: the name of the manufacturer or its trademark; Product name;

product designation;

quantity, pcs.;

batch number;

release date;

type of marking;

technical control stamp.

The gross weight of the box is no more than 40 kg.

6.5. The box is marked according to GOST 14192-96 with additional data: name, brand, size of electrodes;

batch numbers; packaging dates; net weight.

6.6. Packed electrodes are transported by all types of transport in covered vehicles.

During transportation, the placement of boxes should prevent their movement, mechanical damage to the packaging and electrodes, and moisture ingress.

Transportation conditions in terms of exposure to climatic factors - according to group Zh GOST 15150-69.

6.7. Electrodes should be stored in the packaging provided. 6.4, according to the group of storage conditions L GOST 15150-69.

APPLICATION

Mandatory

1. METHOD FOR DETERMINING LANTHANUM OXIDE CONTENT

The method establishes the determination of lanthanum oxide in lanthanum welded tungsten rods and electrodes.

1.1. Essence of the method

The method is based on the separation of lanthanum from tungsten by dissolving a pre-oxidized and calcined test sample to tungsten anhydride (WO3) in a solution of sodium carbonate.

In this case, lanthanum, present in tungsten in the form of La33, precipitates, and the soluble form of lanthanum is additionally precipitated with ammonia in the form of La(OH) 3.

The precipitate is filtered off, dissolved in hydrochloric acid, and all the lanthanum is again precipitated with ammonia in the form of La(OH) 3, which is filtered, washed and calcined to La 2 03.

The error of the method with a mass fraction of lanthanum oxide from 1% to 3% is 0.1% with a mass fraction of lanthanum oxide less than 1% - 0.05%.

1.2. Reagents

Crystalline sodium carbonate according to GOST 84-76, 30% solution.

Aqueous ammonia according to GOST 3760-79, 25% solution.

Hydrochloric acid according to GOST 3118-77, density 1.12 g/cm 3.

1.3. Sample preparation

Tungsten anhydride is pre-calcined in a muffle furnace at 700-750 °C for 1.5-2 hours.

Tungsten powder, a sample from a rod or electrode, is oxidized to anhydride by calcination in a muffle furnace at a temperature of 700-750 °C. In this case, the sample is poured into a porcelain crucible at 1/3 of its height and placed in a muffle at 400-500 °C for 1.5-2 hours, and then the temperature is raised to 700-750 °C and the crucible is kept until the powder is completely oxidized (~ 3 hours).

To ensure uniform oxidation of tungsten, the crucible is removed from the furnace two or three times and the sample is mixed.

1.4. Carrying out analysis

2-3 g of tungsten anhydride are placed in a glass of 150-200 cm 3, 50-70 cm 3 of sodium carbonate solution is added and dissolved when heated.

After dissolving tungsten anhydride, the solution is diluted with distilled water to a volume of -100 cm 3, 20-30 cm 3 of ammonia solution is added, the glass is placed in an electric bath and the precipitate is allowed to coagulate. The precipitate is filtered through a “white tape” filter with an adsorbent, washed with a warm 5% ammonia solution; the filter with the sediment is placed in the glass in which the precipitation was carried out, 15-20 cm 3 of hydrochloric acid is added and the contents of the glass are heated until the sediment is completely dissolved and the filter is mocerated.

The filtrate is neutralized with an ammonia solution using litmus, after which another 15-20 cm 3 of ammonia is added.

The precipitate of La(OH) 3 is allowed to coagulate, then it is filtered through a “white tape” filter with an adsorbent. The precipitate is washed with hot water, to which a few drops of ammonia solution have been added until the reaction to C1 is negative (sample with AgN0 3 and HN0 3).

The washed precipitate with a filter is placed in a pre-calcined and weighed porcelain crucible, ashed and calcined in a muffle furnace at a temperature of 700-750 ° C to constant weight.

1.5. Processing the results

The mass fraction of lanthanum oxide in percent is calculated using the formula

100,

where m is the mass of sediment, g;

t\ is the mass of a sample of tungsten anhydride (WO3), g;

0.7931 - conversion factor from tungsten anhydride to tungsten.

Note. The calcined precipitate of lanthanum oxide contains iron oxide, the amount of which is very small compared to the amount of lanthanum oxide, so the mass of iron oxide can be neglected.

2. METHOD FOR DETERMINING YTTRIUM OXIDE CONTENT

The method establishes the determination of yttrium oxide in yttriated welded tungsten rods and electrodes.

2.1. Essence of the method

The method is based on the separation of yttrium from tungsten by dissolving the test sample in hydrofluoric acid with the addition of nitric acid.

With a mass fraction of yttrium oxide from 1 to 3%, the error of the method is 4-5%.

2.2. Equipment, reagents and solutions

Drying cabinet providing heating to a temperature of (150±50) °C.

A muffle furnace with a thermocouple, providing heating to a temperature of (1100±50) °C.

Platinum cups and crucibles - GOST 6563-75.

Laboratory porcelain glassware - GOST 9147-80.

Hydrofluoric acid (hydrofluoric acid) - according to GOST 10484-78.

Nitric acid - GOST 4461-77.

Aqueous ammonia - GOST 3760-79, diluted 1:1.

Polyethylene funnels.

Distilled water - GOST 6709-72.

Rectified ethyl alcohol - GOST 5962-67*.

Laboratory filter paper - GOST 12026-76.

2.3. Sample preparation

Samples of yttriated tungsten are cleaned of possible contamination by washing them several times with alcohol and subsequent drying in an oven at a temperature of 50-70 °C for 10 minutes. Prepared samples are stored in glass bottles or test tubes with ground stoppers.

2.4. Carrying out analysis

A sample weighing 1 g is placed in a platinum cup with a capacity of 100 cm 3, 25-30 cm 3 of hydrofluoric acid is added and nitric acid is carefully added dropwise until the metal dissolves.

After the tungsten has completely dissolved and the release of nitrogen oxides has stopped, 30 cm 3 of water heated to a temperature of 80-90 ° C is added to the cup.

The solution with the precipitate is allowed to stand for 1 hour, after which it is filtered through a polyethylene funnel. Before filtering, a small amount of adsorbent is placed on the filter.

After transferring the sediment to the filter, the bottom of the cup is wiped with a piece of wet filter and all the contents on it are poured onto the filter with hot water. Then the precipitate is washed five to six times with a hot ammonia solution (60-70 °C) and another two to three times with hot water.

The washed precipitate is transferred to a pre-weighed porcelain crucible, dried in an oven at a temperature of 100-150 °C, and then calcined in a muffle furnace at a temperature of 650-700 °C to constant weight and weighed in the form of yttrium oxide.

2.5. Processing the results

The mass fraction of yttrium oxide in percent is calculated using the formula

Y 2 0 3 = - 100, z J m l

where m is the mass of the calcined residue, g; gp\ is the mass of the sample, g.

3. METHOD FOR DETERMINING THE CONTENT OF THORIUM DIOXIDE

The method establishes the determination of thorium dioxide in thoriated welded tungsten rods and electrodes.

3.1. Essence of the method

The method is based on the formation of a ThF 4 -4H 2 0 precipitate when a sample is dissolved in a mixture of hydrofluoric and nitric acids.

The error of the method at a mass fraction of thorium dioxide from 1.5% to 2% is 0.1%.

3.2. Reagents

Hydrofluoric acid (fluoric acid) - GOST 10484-78.

Nitric acid according to GOST 4461-77.

Aqueous ammonia according to GOST 3760-79, diluted 1:1.

Distilled water according to GOST 6709-72.

3.3. Sample preparation

The samples are boiled for several minutes in an alkali solution until oxides are completely removed from the surface, washed in distilled water and dried in an oven.

* GOST R 51652-2000 is in force on the territory of the Russian Federation.

3.4. Carrying out analysis

A sample weighing 1-2 g is placed in a platinum cup with a capacity of 100 cm 3, 25-30 cm 3 of hydrofluoric acid is added and nitric acid is carefully added dropwise.

Before filtering, a small amount of adsorbent is placed on the filter.

The wet filter is transferred to a porcelain or platinum crucible pre-weighed to constant weight, ashed, calcined at a temperature of 750-800 ° C and weighed.

At the same time, a control experiment is carried out with all reagents.

3.5. Processing the results

The mass fraction of thorium dioxide in percent is calculated using the formula

100,

where m is the mass of sediment Tiu 2, g;

mi is the mass of sediment in the control experiment, g; w 2 - sample weight, g.

Editor R.G. Goverdovskaya Technical editor L.A. Guseva Corrector R.A. Mentova Computer layout I.A. Naleykina

Ed. persons No. 02354 dated July 14, 2000. Delivered for recruitment on September 29, 2004. Signed for publication on October 15, 2004. Uel. pech.l. 0.93. Academician-ed.l. 0.75.

Circulation 90 copies. C 4203. Zak. 908.

IPK Standards Publishing House, 107076 Moscow, Kolodezny per., 14. e-mail: Typed at the Publishing House on a PC

Printed in the branch of the IPK Publishing House of Standards - type. "Moscow Printer", 105062 Moscow, Lyalin lane, 6.

The influence of shielding gases on the technological properties of the arc.

Technological properties of the arc

welding equipment

Welding materials

Special welding methods

1. BRANDS

2. ASSORTMENT

3. TECHNICAL REQUIREMENTS

4. ACCEPTANCE RULES

5. TEST METHODS

6. LABELING, PACKAGING, TRANSPORTATION AND STORAGE

APPLICATION Mandatory

1. BRANDS

2. ASSORTMENT

3. TECHNICAL REQUIREMENTS

4. ACCEPTANCE RULES

5. TEST METHODS

6. LABELING, PACKAGING, TRANSPORTATION AND STORAGE

APPLICATION

1. METHOD FOR DETERMINING LANTHANUM OXIDE CONTENT

2. METHOD FOR DETERMINING YTTRIUM OXIDE CONTENT

3. METHOD FOR DETERMINING THE CONTENT OF THORIUM DIOXIDE

1. BRANDS

2. ASSORTMENT

3. TECHNICAL REQUIREMENTS

4. ACCEPTANCE RULES

5. TEST METHODS

6. LABELING, PACKAGING, TRANSPORTATION AND STORAGE

TECHNICAL CONDITIONS

GOST

23949-80

By Decree of the USSR State Committee on Standards dated January 18, 1980 No. 217, the introduction date was set

Official publication

Reproduction is prohibited

★

1. METHOD FOR DETERMINING LANTHANUM OXIDE CONTENT

1.1. Essence of the method

1.2. Reagents

1.3. Sample preparation

1.4. Carrying out analysis

1.5. Processing the results

100,

2. METHOD FOR DETERMINING YTTRIUM OXIDE CONTENT

2.1. Essence of the method

2.2. Equipment, reagents and solutions

2.3. Sample preparation

2.4. Carrying out analysis

2.5. Processing the results

3. METHOD FOR DETERMINING THE CONTENT OF THORIUM DIOXIDE

3.1. Essence of the method

3.2. Reagents

3.3. Sample preparation

3.4. Carrying out analysis

3.5. Processing the results

100,

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APPLICATION
Mandatory