Stainless steel contains a large amount of alloying elements such as Cr and Ni and is classified into austenitic stainless steel, ferritic stainless steel, and martensitic stainless steel according to the alloy composition. Austenitic stainless steel is the most used in spot welding of stainless steel capacitor discharge spot welding machine factory price, followed by martensitic stainless steel.
Austenitic stainless steel has a high electrical resistivity, about 5 times that of low carbon steel at normal temperature, and has a small thermal conductivity, which is only 1/3 of low carbon steel. It has good weldability and can use a small welding current. Short power-on time. Since the resistivity is large, the shunt through the soldered joint is reduced, so that the dot pitch can be appropriately reduced. Stainless steel has a large coefficient of linear expansion and is prone to warp deformation when welding thin-walled structures. Stainless steel has a high-temperature strength, so it is necessary to increase the electrode force. Otherwise, shrinkage cavities and crystal cracks may occur.
It is recommended to use Class A and Class 3 electrode alloys with higher hardness in the attached table to improve the service life of the electrode. If the heating time is prolonged, the heat-affected zone is enlarged and overheated, the grain in the near-slit zone is coarse, and even grain boundary melting occurs. The cold-rolled steel sheet has a softened zone, which deteriorates the joint performance. Therefore, it is advisable to use harder welding conditions. Table 18 is the recommended process parameters for austenitic stainless steel welding.
Martensitic stainless steel is often used in low temperature or high-temperature tempering after quenching. This steel will be hardened again after stationary type ac spot welding machine price, which will reduce the plasticity of the joint. In order to improve the mechanical properties of the joint, a double-pulse spot welding process after tempering between electrodes should be used. External water cooling of the electrode is generally not used to avoid cracking due to quenching.
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