How to cook stainless steel? Welding technology, equipment

2024 Author: Howard Calhoun | [email protected]. Last modified: 2023-12-17 10:16

How to cook stainless steel is a rather relevant question for modern industry. It is worth noting that this type of steel is a fairly durable material, so its processing has certain nuances. The choice of welding method depends on the thickness of the workpieces and on the chemical composition.

Stainless steel. Key Features

Stainless steel is an alloy of carbon and iron alloyed with chromium. The high content of the latter element ensures high resistance of the material in a corrosive environment. Chromium oxides form a special protective film, thanks to which the base metal retains its resistance. Additionally, steel is alloyed with nickel, cob alt, titanium. The main advantages of stainless steel are high resistance in contact with aggressive environments, high strength, respectively, and a long period of operation. In addition, steel has a good aesthetic appearance.

Features of welding corrosion-resistant steel

This material has a large linear expansion. As a result, under thermal action, the workpieces can be deformed and change their dimensions. Toto avoid such a situation, it is necessary to strictly adhere to the optimal gap between the parts that are connected. The action of high temperature can lead to the fact that the alloy steel loses its properties somewhat, the corrosion resistance decreases. In this case, the weld must be cooled in time. The low thermal conductivity of steel requires a reduction in current strength by about 25%. It is also worth choosing the right welding electrodes, since with a long length they can overheat. Another difficulty is the appearance of refractory carbides on the surface, intergranular corrosion.

Methods of cooking stainless steel

There are many methods for welding stainless steel. With a small metal thickness (1.5 mm), it is advisable to use arc welding (in an inert gas environment). How to cook stainless steel with a thickness of less than 0.8 mm? In this case, a pulsed arc method is used. Thin metals are also connected by an arc with a jet material transfer. Increasingly, the plasma welding method is being used. It can be used for a wide range of workpiece thicknesses. Sections larger than 10 mm are welded under a flux ball. They also use high frequency welding, the laser method.

Argon material welding

This process takes place in a protective gas environment - argon. It protects the material from the effects of oxygen. In a special device, an arc is formed between the part and the tungsten electrode. During the heating process, the edges melt, creating a protected weld pool. A special wire is also constantly fed into the arc tostainless steel welding. The connection process itself is carried out at an angle of 90 °. For the best quality work, it is worth eliminating any oscillatory movements of the electrode. The result is a slag-free seam. Such a connection is of high quality, durability, satisfies all aesthetic requirements. Gas welding of stainless steel is used in many industries: chemical, food industry, automotive, aviation, thermal power engineering. Among the shortcomings, one can single out only the large time spent on the process itself. Also, the technology requires special skills and experience from workers.

TIG welding equipment

First of all, this type of metal connection requires an inverter. There are quite a few modifications and models: "Svarog", KEMPPI Master, BRIMA, etc. The main advantages of the device are ease of operation, small size and weight, stable arc. Inverters can be used for welding almost any metal, while the connections will be of high quality. How to cook stainless steel with an inverter and what should be considered? First of all, it is necessary to choose the correct operating temperature range. Some models do not work outdoors in cold weather. It is also worth considering the power of the device. For domestic use, an inverter with a current of up to 160 A is suitable (for example, "Svarog TIG 200 P", PRO TIG 200 P) The parts are cleaned and degreased before connection. For welding, you will also need a gas cylinder with argon. Although in practice the use of diluted gas is allowed. A burner is attached to the gas hose, in the holder of which a tungsten electrode is inserted. On the handle of the burner there are buttons for supplying current and gas. A welding wire of the same material as the parts to be joined is also required.

How semiautomatic welding works

How to cook stainless steel when repairing a car, at home? In this case, the semi-automatic welding method is often used. It can occur both in a protective environment and without the use of gas. Semiautomatic devices are also used at large automotive enterprises, which indicates the high quality of the welded joint. In this case, a special wire acts as an electrode and filler material. There are several ways to work with the equipment: short arc, spray transfer, stainless steel pulse welding. The technology provides for operation without shielding gas, however, in this case, special powder electrodes should be chosen. This method is also suitable for outdoor work. There is no need to buy (and, accordingly, spend additional funds) a gas cylinder. This has its drawback - over time, the welded joint can become rusty. Therefore, experts still recommend using special stainless steel electrodes and welding using argon. To date, there are many varieties of semiautomatic devices, both domestic ("FEB", "Svarog"), and foreign production (BRIMA, EWM, TRITON, etc.). The choice of apparatus depends on the tasks, volumes of welding andcharacteristics of the materials to be joined.

Using electrode welding

How to cook stainless steel if there are no special requirements for the quality of the seam? As a rule, in domestic conditions, when connecting all kinds of pipes, in small-scale production, and also to obtain a short seam, electrode welding is used. The essence of this process is the formation of a compound from the material of the workpiece and the metal of the electrode.

The advantages of the technique include ease of execution, the ability to connect different metals (both thin and rather large sections). There is no need to use gas, which reduces the cost of the process. Also, welding with electrodes makes it possible to approach hard-to-reach areas of the part. There are certain disadvantages of this technology. Firstly, the weld requires cleaning from the resulting slag. Secondly, the welding speed is small.

How to choose electrodes for welding

Stainless steel electrodes are widely used for joining corrosion-resistant alloys that operate at high temperatures. As a rule, the rods are made on the basis of nickel, chromium. Two types of electrodes can be used in manual arc welding. The first - work in conditions of direct current. The main coating most often consists of magnesium, calcium carbonates. Welding electrodes with rutile coating can work with alternating current. When welding using argon, various tungsten rods are used. Thanks to the high workingtemperature, they do not melt. There are many varieties of them. Green electrodes (WP) consist of pure tungsten. They provide a sufficiently high resistance of the arc. White - WZ-8 - doped with zirconium oxide. Thorium oxide is added to the red electrodes. This is the most common group, the rods have a high resistance. Also, lanthanum, cerium can be included in tungsten electrodes.

Weld joint processing

After the process of joining the parts, it is necessary to clean the seam. This should be done in order to improve the appearance, extend the service life. Otherwise, corrosion may occur in this area. First of all, mechanical cleaning of the weld is carried out. The junction looks more aesthetically pleasing after sandblasting. The next step is to sand the surface. In this case, it is not recommended to use abrasives based on corundum, as it can provoke the appearance of corrosion. It is worth noting that all these manipulations are aimed at improving the appearance of the part. Etching and passivation will help protect the weld from destruction. Etching is a surface treatment with special chemicals that destroy the resulting scale. During passivation, a special substance is applied to the junction. Under its influence, a protective film appears (from chromium oxide).

Laser alloy welding method

One of the most modern and technologically advanced joining methods is laser welding of stainless steel.

The essence of this method is to use a laser beam as a heating source. Such welding is distinguished by high speed, high concentration of energy at the junction. The thermal effect on the zone, which is in close proximity to the seam, is insignificant. Therefore, the risk of hot or cold cracking is minimal. The resulting seam is distinguished by its strength, there is no porosity. It is also possible to deliver shielding gas to the junction of alloying elements. Since there are no welding electrodes, foreign compounds do not get into the seam. Laser welding can even be used for jewelry, as all seams are thin, neat and strong. The only drawback is that the equipment is quite expensive, so the mass use of such installations is not yet possible.