The effect of nitrogen content on the susceptibility to stress-corrosion cracking of type 20Cr-20Ni and AISI type 310 stainless steels

The effect of nitrogen content on the susceptibilities of type 310 and 20Cr-20Ni stainless steels to stress-corrosion cracking were studied by exposing the U-bend specimens of the alloys containing various nitrogen levels to magnesium chloride solutions boiling at 154°C. It was found that the increase in nitrogen levels up to 0.161 wt.% did not induce cracking in type 20Cr-20Ni alloys even after long exposure times. At the same time, increase in nitrogen content decreased the crack initiation time in type 310 stainless steel and increased the depth of penetration. Furthermore, the rate of propagation of the stress-corrosion cracks in the U-bend stainless steel specimens of type 310 decreased with increase in exposure time.