Selection of welding rods for dissimilar steel welding

1) Carbon steel + low alloy steel (or low alloy steel + low alloy high strength steel) with different strength levels

Generally, the strength of the weld metal or joint is not lower than the minimum strength of the two weld metals. The strength of the selected weld metal should ensure that the strength of the weld and joint is not lower than the strength of the base material. At the same time, the plasticity and impact toughness of the weld metal should not be lower than the performance of the base material with higher strength and poorer plasticity. Therefore, the electrode can be selected from steels having a lower strength level. However, in order to prevent welding cracks, the welding process should be determined according to the steel grade with higher strength grade and poor weldability, including welding specifications, preheating temperature and post-weld heat treatment.

2) Low alloy steel + austenitic stainless steel

The electrode should be selected according to the value defined by the chemical composition of the deposited metal. Generally, the Cr25-Ni13 austenitic steel electrode with high content of chromium and nickel and good plasticity and crack resistance is used to avoid brittle hardening. Crack caused by the organization. However, the welding process and specifications should be determined according to stainless steel with poor weldability.

3) Stainless composite steel plate

Three different performance electrodes should be selected for the welding requirements of the base layer, the composite layer and the transition layer. For the welding of the base layer (carbon steel or low alloy steel), the structural steel electrode of the corresponding strength grade is selected; if the composite layer is directly in contact with the corrosive medium, the austenitic stainless steel electrode of the corresponding composition should be selected. The key is the welding of the transition layer (ie, the interface between the complex layer and the base layer). The dilution effect of the matrix material must be considered. The Cr25-Ni13 austenitic steel electrode with high chromium and nickel content, good plasticity and crack resistance should be selected.