Stainless steel welding: what and how best to cook stainless steel at home

Performing such a technological operation, as stainless steel welding, it is important to consider both the physical properties of the material, and its chemical composition. Only in this case you can count on it, that the connection will be made efficiently and reliably.

Argon welding of stainless steel

Difficulty factors for welding stainless steel parts

Stainless steel welding complicates that, that this material belongs to the category of high-alloy alloys, so, it contains a fairly large number of elements, affecting its basic properties. In stainless steel, in particular, such an element is chrome. Its content in this alloy may be 12-30%. Chrome along with such elements, like nickel, titanium, manganese, molybdenum, forms anticorrosive properties of stainless steel, but at the same time endows it with other features, affecting weldability.

For those, who does not like to read long articles and delve into the technical details, we suggest you watch two videos at once with the most relevant options for stainless steel welding for a home builder - an electrode with an inverter and again an inverter, but already in a shielding gas environment (argon).

Stainless steel welding should be performed taking into account the following specific characteristics of this material.

Quite a high coefficient of linear expansion

For this reason, the welding of stainless steel is always accompanied by significant deformation of the parts, connecting. In some cases, when the welded parts have a significant thickness and there is no gap between them, such deformations can even lead to large cracks.

Low thermal conductivity

The thermal conductivity of stainless steel is 1.5–2 times lower, than low-carbon alloys. This feature of the material leads to that, the connecting parts in the welding zone are melted even at smaller (on 15-20%), than when welding low-carbon steel products, current strength.

Intergranular corrosion

At strong heating (over 500 degrees Celsius) in stainless steels there is a so-called intergranular corrosion. This is why it happens, that along the edges of the grains of the metal structure begin to form layers, consisting of chromium carbide and iron. This phenomenon can be avoided not only by careful selection of the welding mode, but also by forced cooling of welded stainless steel parts, for which you can use ordinary water. However, it should be borne in mind, that only details can be cooled by water, made of chromium-nickel steels, which have an austenitic internal structure.

Overheating of electrodes with chromium-nickel rods

Due to the low thermal conductivity of the materials to be joined and their increased electrical resistance, the welding of stainless steel parts is accompanied by strong heating of the electrodes., rods which have chromium-nickel composition. To avoid this undesirable phenomenon, use electrodes for welding stainless steel up to 35 div.

Welding electrodes Sabaros ME 101 3,2 mm for welding stainless steels

The most common methods of welding stainless steel

Welding of stainless steel products, characterized by high chromium content can be performed using several technologies. Here, in particular, the following types of welding belong:

• argon arc (using a tungsten electrode and AC / DC TIG modes);
• performed in MMA mode with coated electrodes;
• semi-automatic electric arc welding in argon, which is carried out in the MIG mode and with use of a wire from stainless steel;
• so-called cold welding of stainless steel, performed under high pressure (the name of this technology is due to the fact, that it does not involve melting the metal in the process of its connection);
• suture technology and contact spot welding.

Technology of welding of details from stainless steel provides careful degreasing of surfaces by means of acetone or aviation gasoline. This is done for that, to reduce the porosity of the seam is performed, make the welding arc more stable, carefully clean the edges of the parts, connecting. Only after thorough stripping can the operation be performed in the chosen way. There are several basic ways to weld stainless steel parts, as well as technology, which are used quite rarely. In any case, make a decision about it, how to cook stainless steel, should be based on specific conditions and requirements, presented to the molded joint.

Coated electrode welding (MMA)

Welding of stainless steel parts by MMA technology, involving the use of coated electrodes, is the most common technology. This method is quite simple, it can be used at home, but it does not allow to receive a seam of the highest quality.

Which is convenient, such welding of stainless steel can be performed even at home, but for this you will need a special welding machine, which is called an inverter. To allow the stainless steel to be welded with an inverter, which has high reliability, it is necessary to choose the right electrode for a particular brand of stainless steel. All electrodes, by means of which welding of products from stainless steels is carried out, are divided into two main types:

• with rutile coating based on titanium dioxide (welding with such electrodes, providing a small spray of metal and a stable arc, performed on direct current and reverse polarity);
• with a coating based on magnesium and calcium carbonate (such electrodes stainless steel is welded to a direct current of reverse polarity).

To understand, what electrodes to cook stainless steel, just look in GOST 10052-75, which presents all types of such consumables, and also stipulates, which of them should be used to work with metal of a specific chemical composition. To choose stainless steel electrodes, that meet the requirements of this Guest, it is enough to know the brand of metal, parts to be connected from.