Development of welding rods for stainless steel processing

When processing and welding stainless steel, stainless steel welding rods need to be used. In addition to meeting the standard general welding process performance and mechanical properties of the welded joint, this type of welding rod should also ensure that the welded joint can meet the corresponding corrosion resistance requirements. Therefore, it is necessary to make the following requirements for the coating and welding core of stainless steel processing welding electrodes.

First, various alloying elements are transferred through the welding core and coating, so that the weld metal becomes a structure containing a certain amount of austenite and ferrite, thereby ensuring that the weld metal for stainless steel processing not only has excellent crack resistance, but also has Good resistance to corrosion by corresponding media.

Secondly, through the welding core or coating, a certain amount of carbide-forming elements, such as niobium, molybdenum, titanium, etc., can be penetrated into the weld metal to form stable carbides with carbon elements, thereby avoiding the formation of chromium at the grain boundaries. of carbides.

In addition, the increase of carbon element will also lead to the formation of intergranular corrosion in austenitic stainless steel welds. Therefore, the carbon content in the raw materials of the welding core and coating should be strictly controlled. It is recommended to use low-carbon or ultra-low carbon welding core, and use low-carbon or carbon-free iron alloys and metal elements as the raw materials of the coating.

It is also necessary to strictly control the sulfur and phosphorus content in the stainless steel welding core and coating to reduce the risk of forming hot cracks in the weld.

Regarding the model of the welding rod selected for stainless steel processing and welding, since the model is the number specified for the welding rod in the national standard, it is used to identify the mechanical properties and chemical composition of the deposited metal, coating type, welding position and welding current type of various welding rods. The technical requirements, performance indicators, and inspection methods of welding rods marked with models should comply with national standards. National standards usually only stipulate the most basic requirements for this type of welding rod.

The models of domestic stainless steel processing electrodes have developed rapidly. From GB983-67 to GB/1983-1995, there were originally less than 20 models of stainless steel electrodes, and now there are more than 50 models of stainless steel electrodes. Nowadays, the types of welding rods for stainless steel processing are relatively complete, including welding rods for ferritic stainless steel, welding rods for austenitic stainless steel, and welding rods for austenitic ferritic duplex stainless steel, etc. Stainless steel welding rods include welding rods containing stable elements, low carbon and ultra-low carbon welding rods, and special stainless steel welding rods.