Formation of martensite in 304 grade stainless steels and their welds

The formation of martensite in metastable austenitic stainless steels was investigated. The results showed that the formation of martensite in 304 grade stainless steels due to the exposure to cryogenic temperatures is negligible. The amount of formed martensite is dependent on the chemical composition of the actual heat but for standard grades the amount is not expected to exceed a very few percent. In welds the formation of martensite is not promoted by the presence of delta-ferrite. The formation of martensite due to cold forming at room temperature can reach around 20%. Cold forming with subsequent exposure to cryogenic temperatures does not lead to additional formation of martensite due to the exposure to low temperatures. Cold forming at low temperatures leads to the highest amount of martensite formed in metastable stainless steels.