Wolfram (tungsten) electrode

Welding is the most common method of fastening components. It allows making firm joints of complex shape. In many industries this process is well-automatized and this makes it even more widely-used. There is a need not only to weld various steels, but also non-ferrous metals also. Widely-used wolfram electrodes are perfectly suitable for this. For example, such metals as molybdenum, nickel, titanium and others are well-welded with wolfram electrodes.

It is very easy to buy wolfram electrodes. Metotechnics offers a wide size range of products. They can be ordered on the Prices page so as via e-mail or by phone.

See the corresponding sections of the provided page for wolfram products, their production, application and grades.

Grades

Electrodes have the following grades: WP, WL-15, WY-20, WT-20 etc.

Depending on the standard of producing a tungsten electrode, the chemical composition may differ depending on the grade. E.g., in compliance with GOST 23949-80, WL-15 wolfram shall contain at least 99.95% of W. At the same time, according to another standard TC 48-19-527-91, products can be made of WL-20, with 97.90-98.30% tungsten content. So they differ in lanthanum weight percent and additive amount.

Grade	Wolfram weight percent. min	Additive
WP	99.92	Absent
WL-15	99.95	Lanthanum oxide
WY-20 (Blue)	99.89	Yttrium oxide
WY-20 (Violet)	99.95	Yttrium oxide
WY-20 (Green)	99.95	Yttrium oxide
WY-20	97.62	Yttrium oxide
WT-20	99.91	Thorium dioxide

Additives are used for improving alloy properties.

The chemical composition of described materials is regulated by GOST 23949-80, TC 48-19-527-91, TC 48-19-221-83, TC 48-19-27-88 standards.

Tungsten electrodes are widely used worldwide. So they have an international marking.

Letter W means “wolfram”; letters P, L, Y, T mean the additive (alloying element): P - pure metal; L - lanthanum; Y - yttrium; T - thorium; С - cerium; Z - zirconium. The last section of the marking means the amount of the alloying element.

Let us take WY-20 as an example. It is a nonconsumable wolfram electrode with yttrium additive with weight percent 2%.

Product colour marking

Wolfram electrodes with different additives look the same: they are round-section rods of equal length. But different grades have different weldability. For simplifying the work with the products and minimizing the possibility of a wrong electrode choice they are marked with colours. Each colour corresponds to a certain grade.

They are given below:

• brown, white- WZ-4, WZ-8 (zirconium oxide);
• green - WP (wolfram without additives);
• black, golden, blue - WL-10, WL-15, WL-20 (lanthanum oxide);
• dark-blue - WY-20 (yttrium oxide);
• yellow, red, purple, orange - WT-10, WT-20, WT-30, WT-40 (thorium oxide);
• rosy, grey - WC-10, WC-20 (cerium oxide);
• turquoise - WS-2 (mixture of rare-earth metal oxides).

Production

Forging and drawing are the main methods of producing wolfram electrodes. The method depends on the blank size and end semifinished product. As a rule, drawing is used for making products with diameter less than 3 mm and forging is used for making larger products. Blanks are processed in several stages. The blank diameter is reduced and the length is increased at every stage.

Tungsten is pressurized after heating only. As it is known, it is not plastic enough under room temperature. So the above-mentioned technological operations are performed simultaneously with heating the blanks.

Drawn tungsten electrodes are pickled for cleaning the surface from grease and other contaminants. Also according the most standards for wolfram electrode, the surface is processed with cutting (polishing). Blank straightness is another important requirement of regulatory documents.

GOST 23949-80, TC 48-19-527-91, TC 48-19-221-83, TC 48-19-27-88 regulate wolfram electrode straightness, size and their tolerance extremes, properties, supply condition and other requirements.

Nonconsumable wolfram electrodes should be sharpened before application. The tip shape and sharpening angle determine the quality and size of the weld so as the welding depth. The working ends of WP and WL electrodes should have a ball shape and WC, WY, WT, WZ electrodes should have a conic shape. Also the tip sharpening length and angle also play a great role. The length should be equal to the product of wolfram electrode diameter product by 2.5. The angle depends on the current magnitude of welding: the higher the current is, the obtuser sharpening angle is. If welding is performed with a low current, the angle should be 10-20 degrees and if it is performed with a high current, the angle should be 60-120 degrees.

Application

The main application of a tungsten electrode is arc welding. It is used for connecting components made of non-ferrous metals or their alloys (the chemical composition may be different) so as high alloyed steels. The weld is very durable. Besides welding plasma cutting, facing and spraying also should be mentioned.

Arc welding belongs to thermal class where burn-off is provided by heat energy. It can be manual, semi-automatic or automatic. Arc welding is the most widely-used one among other types. Heat energy is generated by a voltage arc that burns between the electrode and product (part, blank). An arc is a powerful and stable electric discharge in ionized gas or metal vapour. An electrode supplies the current to the weld area for making an arc.

Welding wolfram electrode is a nonconsumable round-section rod. The molten weld pool is formed due to the filler wire and melted material of the welded products.

Welding with nonconsumable wolfram electrodes is performed in protective argon atmosphere. It protects the molten weld pool, arc area and the electrode from nitrogen, hydrogen and CO₂ that can affect the weld properties.

Additives to electrode material (see section “Grades”) improve the welding process a lot. Thorium improves the arc ignitability and its stability, yttrium and lanthanum allow using the welding wolfram electrode in different current environments.

Prices

The cost of wolfram electrodes is given at the Prices page.