A correctly selected tungsten electrode is the key to successful welding!

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The comfort of the welding process and the quality of the produced seam directly depend on the correct choice of electrode.

Tig welding uses an electric arc that burns between the end of the electrode and the workpiece. The weld pool is protected by an inert gas - argon. The electrode is non-consumable, so it is easier for the welder to control the air gap and move the torch smoothly, which affects the quality of the seam. At the same time, the argon welder must be able to correctly choose the color of the tungsten electrode, which determines the reliability of the connection and the service life of the consumables. Our article will help you understand the differences in colors of non-consumable electrodes.

WP, green

Available for welding magnesium, aluminum and their alloys.

The composition contains pure tungsten in an amount of 99.5%. Designed to operate on alternating current, ensuring stable combustion of the electric arc. Suitable for use with or without an oscillator. Argon or helium can be used as a shielding gas. Since the thin tip quickly overheats and crumbles, spherical sharpening is recommended.

Working principle of argon arc welding

In international designation, the argon arc method has the abbreviation TIG. It is actively used in production and workshops. It is used to connect cracked car parts (crankcase pans, engine cooling blocks), assemble containers for the food and chemical industries, make stainless heated towel rails, manifolds, liquid filters, etc. In a garage, such a device can successfully perform body repairs or produce small parts. products.

The operating principle of argon welding is to join metals with an electric arc in an inert gas environment. The process requires a current source that lowers the voltage and increases the amperage. The current is supplied to a torch equipped with a tungsten electrode. It is non-consumable, so it is easier for the welder to control the length of the arc, which should be 2-5 mm. The ground cable is connected to the product.

Touching the tip of a tungsten needle to the part initiates an electric arc. For thin seams, transverse vibrations are not required - the electrode is moved evenly, from right to left along the seam line, the joint surface is smooth as a mirror. If there is a gap between the parts or it is necessary to expand the boundaries of the seam, then when moving the torch, the welder makes slight oscillations on the sides, stretching the weld pool. This promotes the formation of small scales.

Tig welding process.

The arc temperature ranges from 2000 to 5000 degrees, depending on the current strength. This allows the edges of the metal to be melted and joined with a thin seam. To strengthen the structure, filler wire is used, fed with the welder’s second hand into the weld pool. Thus, you can increase the height of the bead, give the seam a scaly appearance, and even perform metal surfacing for subsequent mechanical processing (turning on a lathe, grinding).

To protect the weld pool from the external environment, the inert gas argon is used. It is supplied from the cylinder to the burner and displaces normal air. This eliminates the formation of pores in the seam structure. The connection is tight and durable. At the same time, the shielding gas cools the tungsten electrode and ceramic nozzle so that they do not overheat. At the final stage, when the arc is extinguished, argon helps to solidify the seam.

Scheme of the argon arc welding process.

Pros and cons of the TIG method

The TIG method has clear advantages over other welding methods, but working with an argon welding machine also has several disadvantages that you need to be prepared for when choosing this welding method.

Pros of the TIG method

1. local heating eliminates serious deformation of the product;
2. a thin tungsten needle allows you to create narrow, neat seams;
3. You can weld with or without an additive, affecting the height of the bead;
4. the connection is obtained without a slag crust on top;
5. in most cases no follow-up is required
6. mechanical processing; can weld stainless steels and non-ferrous metals;
7. the seams are sealed and can withstand high pressure;
8. there are no metal splashes sticking to the surface.

Disadvantages of the TIG method

1. connection speed is inferior to MIG;
2. the burner cap interferes with work in hard-to-reach places;
3. the ceramic nozzle slightly limits the visibility of the weld pool;
4. the quality of the seam depends on the user’s skills (you won’t be able to immediately take it and cook it like a semi-automatic machine);
5. it is necessary to constantly feed the additive with the second hand and control its length (when welding, the length of the wire quickly shortens, and long pieces are inconvenient to hold in your hands,
6. because they are “walking”);
7. tungsten electrodes are more expensive than coated ones;
8. additional costs for argon;
9. It is impossible to qualitatively weld parts outdoors in strong winds (argon is blown away and the weld pool remains unprotected).

WT-20, red

Used for welding: copper, bronze, nickel, alloy steel, titanium, metals with a high melting point (tantalum, molybdenum).

A mixture of tungsten and thorium oxide. Thorium is a radioactive material, so sharpening the rod must be carried out in protective equipment, otherwise the dust will affect the health of the welder. For irregular welding, the normal process with natural ventilation is allowed. For continuous work with red tungsten electrodes, forced ventilation is required, and when welding in containers, masks with turbo blocks are required.

The required special form of sharpening is in the form of a platform with protrusions. It is better to cook with direct current. Due to the addition of thorium, the rods can withstand elevated temperatures without deformation, therefore they are used for welding thick metals.

How to choose tungsten electrodes

Tungsten electrodes are used in argon arc welding, that is, welding with a non-consumable electrode in an argon shielding gas.

The melting point of tungsten is 3410 °C, the boiling point is 5900 °C. It is the most refractory metal in existence. Tungsten remains hard even at very high temperatures. This allows you to make non-consumable electrodes from it. In nature, tungsten occurs mainly in the form of oxidized compounds - wolframite and scheelite.

In argon arc welding, an arc burns between the part being welded and a tungsten electrode. The electrode is located inside the welding torch. For welding in a shielded gas environment, direct current of straight polarity is usually used. Sometimes reverse polarity current or alternating current is used. In such cases, it is advisable to use tungsten electrodes with alloying additives, which increase the stability and stability of the welding arc.

To improve the quality of the electrode (for example, resistance to high temperatures, increasing the stability of the arc), oxides of rare earth metals are introduced into pure tungsten as an additive. There are a number of varieties of tungsten electrodes, depending on the content of these additives. This determines the brand of the electrode. Nowadays, it is easy to remember the brand of the electrode by the color one end is painted. Tungsten electrodes are divided into three types: Constant (WT, WY), Variable (WP, WZ) and Universal (WL, WC).

International brands of electrodes

W.P.

(green) - Pure tungsten electrode (content not less than 99.5%). The electrodes provide good arc stability when welding with alternating current, balanced or unbalanced with continuous high-frequency stabilization (with oscillator). These electrodes are preferred for AC welding of aluminum, magnesium and their alloys, as they provide good arc stability in both argon and helium environments. Due to the limited thermal load, the working end of the pure tungsten electrode is formed into a ball.

Main materials to be welded: aluminum, magnesium and their alloys.

Check prices for WP

(green) electrodes, you can follow the link.

WZ-8

(white) - Electrodes with the addition of zirconium oxide are preferred for alternating current welding, when even minimal contamination of the weld pool is not allowed. The electrodes produce an extremely stable arc. The permissible current load on the electrode is slightly higher than on cerium, lanthanum and thorium electrodes. When welding with alternating current, the working end of the electrode is processed in the shape of a sphere.

The main materials to be welded are: aluminum and its alloys, bronze and its alloys, magnesium and its alloys, nickel and its alloys.

View prices for WZ-8

(white) electrodes, please follow the link.

WT-20

(red) - Electrode with the addition of thorium oxide. The most common electrodes, since they were the first to show the significant advantages of composite electrodes over purely tungsten electrodes when welding with direct current. However, thorium is a low level radioactive material, so fumes and dust generated during electrode sharpening can affect the welder's health and the safety of the environment. Relatively small releases of thorium during occasional welding, as practice has shown, are not risk factors. But, if welding is carried out in confined spaces regularly and for a long time, or the welder is forced to inhale dust generated when sharpening the electrode, it is necessary for safety reasons to equip the work area with local ventilation. Thoriated electrodes work well when welding on direct current and with improved current sources, and depending on the task at hand, you can change the angle of sharpening of the electrode. Thoriated electrodes retain their shape well at high welding currents, even in cases where a pure tungsten electrode begins to melt to form a spherical surface at the end. WT-20 electrodes are not recommended for AC welding. The end of the electrode is processed in the form of a platform with protrusions.

The main materials to be welded are: stainless steels, metals with high melting points (molybdenum, tantalum), niobium and its alloys, copper, silicon bronze, nickel and its alloys, titanium and its alloys.

View prices for WT-20

(red) electrodes, please follow the link.

WY-20

(dark blue) - Yttriated tungsten electrode, the most durable non-consumable electrode in use today. Used for welding particularly critical joints on direct current of direct polarity, the content of the oxide additive is 1.8-2.2%, yttriated tungsten increases the stability of the cathode spot at the end of the electrode, as a result of which the arc stability is improved in a wide range of operating currents.

Main materials to be welded: welding of particularly critical structures made of carbon, low-alloy and stainless steels, titanium, copper and their alloys using direct current (DC).

View prices for WY-20

(dark blue) electrodes, please follow the link.

WC-20

(gray) - An alloy of tungsten with 2% cerium oxide (cerium is the most common non-radioactive rare earth element) improves the emission of the electrode. Improves initial arc start and increases permissible welding current. WC-20 electrodes are universal; they can be successfully welded with alternating current and constant direct polarity. Compared to a pure tungsten electrode, a cerium electrode provides greater arc stability even at low current values. Electrodes are used for orbital welding of pipes, welding of pipelines and thin sheet steel. When welding with these electrodes at high current values, a concentration of cerium oxide occurs at the hot end of the electrode. This is a disadvantage of cerium electrodes.

The main materials to be welded are: metals with a high melting point (molybdenum, tantalum), niobium and its alloys, copper, silicon bronze, nickel and its alloys, titanium and its alloys. Suitable for all types of steels and alloys on AC and DC

View prices for WC-20

(gray) electrodes, please follow the link.

WL-20 , WL-15

(blue, gold) - Tungsten lanthanum oxide electrodes have very easy initial arc starting, low burn-through tendency, stable arc and excellent arc re-striking performance. The addition of 1.5% (WL-15) and 2.0% (WL-20) lanthanum oxide increases the maximum current, the electrode carrying capacity is approximately 50% greater for a given size when welding with alternating current than pure tungsten. Compared to cerium and thorium electrodes, lanthanum electrodes have less wear on the working end of the electrode. Lanthanum electrodes are more durable and cause less tungsten contamination of the weld. Lanthanum oxide is evenly distributed along the length of the electrode, which allows the initial sharpening of the electrode to be maintained for a long time during welding. This is a significant advantage when welding with direct (straight polarity) or alternating current from improved welding current sources, steels and stainless steels. When welding with alternating sinusoidal current, the working end of the electrode must have a spherical shape.

Main materials to be welded: high-alloy steels, aluminum, copper, bronze. Suitable for all types of steels and alloys on AC and DC.

Check out prices for
WL-20 here and WL-15
here.

TIG Welding Tips

They weld using direct current (steel, stainless steel, titanium, brass, copper, cast iron, as well as dissimilar compounds). Each material requires its own filler wire, and the better you select the one that matches the chemical composition, the stronger, more beautiful and more reliable the connection will be. The burner should be connected to “-”, and the ground clamp to “+”. At the same time, we get straight polarity, which gives us a more stable directed arc and deep penetration. When choosing a tungsten electrode, you need to pay attention to its diameter. it is selected based on the thickness of the parts being welded.

For DC welding, you need to remember the most important requirement: the tungsten electrode must be sharpened very accurately and sharply. At large enterprises, special machines and machines with a diamond wheel are used to sharpen tungsten electrodes, but without one, you can use a regular flap wheel with fine grain or a sharpening machine. Sharpening is carried out to the tip of the electrode, but do not allow it to overheat. tungsten becomes more fragile and simply begins to crumble. You also need to remember about the shielding gas, it must be high-frequency argon (the volume fraction of argon must be at least 99.998%).

If the gas is bad, then it will immediately make itself known; the most important sign is the darkening of the weld seam. A regulator must be installed on the cylinder; it can be either with pressure gauges or a float type. Increasingly, most serious enterprises use imported gearboxes with two rotameters and use the second one for blowing. This in turn provides protection for the reverse seam bead (welding of sheets and pipes).

The welding itself is done from right to left, with a torch in the right hand, and filler material in the left hand (if necessary). If the machine has the “current decay” and “gas after welding” functions, then you should not forget about them, the first will give you a smooth current decrease at the end of welding, and the second will continue to protect the weld seam during the cooling process. The burner should be at an angle of 700 to 850, the additive is supplied at approximately an angle of 200 smoothly and progressively. At the end of welding, there is no need to rush and tear the torch away from the welding site because this will result in a longer arc and poor seam protection.

Aluminum is welded using alternating current; during preparation, tungsten is not sharpened like a needle, but only slightly rounded. When welding aluminum, an important part must be given to the preparation of both the material and the additive. First, the surface must be cleaned and degreased. Secondly, remove the chamfers if the thickness does not allow for full penetration. Due attention is also paid to the additive; it is necessary to choose the chemical correctly. composition, it can be pure AL 99%, AlSi (silumin) or AlMg (duralumin). The rest just requires practice.

How to protect yourself

And in the end, I would like to note that with this type of welding you need to take proper care of protective equipment. Choose only those protective equipment that will not only be comfortable but also safe because... TIG welding produces very strong ultraviolet radiation, and we only have one eye. We recommend that you consider a modern, highly effective means of protection - the Chameleon mask.

WC-20, gray

Used for welding: copper, bronze, nickel, alloy steel, titanium, metals with a high melting point (tantalum, molybdenum).

A mixture of tungsten and thorium oxide. Thorium is a radioactive material, so sharpening the rod must be carried out in protective equipment, otherwise the dust will affect the health of the welder. For irregular welding, the normal process with natural ventilation is allowed. For continuous work with red tungsten electrodes, forced ventilation is required, and when welding in containers, masks with turbo blocks are required.

What are alloying additives and rare earth metals?

We have looked at the alphanumeric designations of tungsten electrodes, now it’s time to talk about the rare earth metals (elements) that are part of the electrodes, or rather, alloying additives (additives).

Rare earth metals are a group of 17 elements that include scandium, yttrium, lanthanum and lanthanides. All these metals are silvery-white in color, similar in chemical and physical properties, and form refractory oxides that are practically insoluble in water.

These metals received the name “rare earth” due to the fact that they are rarely found in the earth’s crust, and these metals are also difficult to mine and industrially produce.

The most commonly used additives in tungsten welding electrodes are lanthanum, cerium, yttrium, zirconium and thorium.

WY-20, dark blue

They are used in welding molybdenum, tantalum, copper, bronze, niobium, nickel, titanium. Universal by type of current (AC/DC).

The composition includes the addition of 2% cerium oxide, a non-radioactive element, which is safer for the welder to work with. Cerium facilitates easy initial start of the arc and allows increasing the welding current without harm to the equipment. The electrodes hold the arc perfectly at low currents when welding thin sheet steel. The most common application is orbital pipe welding.

Color marking

A tungsten electrode for argon welding can be made from both pure metal and material with impurities.
The use of various additives can improve the stability of the arc. Depending on the impurities used, classification is carried out according to properties. Tungsten welding can be performed using different currents, both in magnitude and type. There are three groups that differ in the type of operating current:

• constant;
• variable;
• universal (suitable for different types of current).

WL-20, blue and WL-15, gold

They are used to cook aluminum, bronze, copper, and alloy steel. You can operate on alternating and direct current of any polarity, as well as on alternating sinusoidal current.

The number on the stamp indicates the content of lanthanum oxide - 2% and 1.5%. The substance slows down the wear of the needle tip, facilitates initial and repeated ignitions of the arc, and reduces the likelihood of burns. Thanks to lanthanum oxide, the welding current can be increased by 50% compared to the maximum of pure tungsten rods. Blue and gold electrodes hold an edge better, and tungsten pollutes the weld pool less.

Which brands are the best?

Tungsten electrodes are presented by both foreign and domestic manufacturers.

The most popular were:

• products of the Swedish company ESAB, manufactured not only in Europe, but also at Russian factories;
• the high price of Fubag rods from Germany corresponds to their quality;
• the entire range of tungsten electrodes is in the catalog of the Italian brand BlueWeld;
• lanthanum wire EVL from Ecotek plant.

In addition to products from large factories, trading enterprises offer products from many Chinese manufacturers. The most popular were Shaanxi Yuheng Tungsten Molybdenum Industrial Co., Ltd, which has been producing tungsten electrodes for over 15 years, Hangzhou Linan Dayang Welding Material Co., Ltd, etc.

The essence of the welding process with TIG equipment

If you are already familiar with types of welding such as MMA and MIG-MAG, then you probably know that the former uses an electrode as the main consumable material, and the latter uses a moving wire.
TIG machines also use an electrode, but this time it is made of tungsten, a material that is refractory. Protection against oxidation is provided by argon gas, which is why the process is often called argon arc welding. The English abbreviation TIG means Tungsten (tungsten) Inert (inert) Gas (gas), which affects the most important elements in the work.

Why is there a filler rod here? It is fed manually to form the seam. Under the action of an arc, the metal melts while in a protected gas environment and creates a high-quality connection.

In this article we will not focus on how the device itself is selected. For this purpose, a separate material has been created that will help you understand how to choose an argon arc machine for TIG welding.

Sharpening

The shape of the electrode tip affects the stability and energy of the electric arc.
They, in turn, determine the dimensions of the weld pool, the depth and width of the resulting seam. In addition to the parameters of the workpieces, when choosing a sharpening shape, the type of electrode is also taken into account. The common shape for all electrodes is a cone with an acute inclination angle. For grades P, L, a small ball is formed at the tip of the cone. This allows you to withstand high thermal loads. For rods with the addition of thorium (grade T), only a small semicircular protrusion is formed.

A machine used for sharpening electrodes.

Sharpening is carried out using several methods:

• manual sharpening machine;
• electric sharpener;
• specialized machine;
• chemical influence.

During welding, tungsten rod does not melt like fusible electrodes. But some burnout occurs. Therefore, from time to time the sharpness of the tip should be checked and, if necessary, sharpened again.