Microstructure and fracture toughness of 316L high nitrogen weld metal produced by high-pressure nitrogen arc welding

摘要

Austenitic stainless steel of SUS316L was welded by the GMA process in high-pressure nitrogen atmospheres up to 6.1 MPa(60atm). The fracture toughness of the weld metals was measured by means of the Charpy impact test at test temperature in therange from 77K to 290K The influence of nitrogen content and microstructure on the toughness of the weld metal has been investigated The content of nitrogen of GMA weld metal reached about 6700 ppm at the maximum welding pressure of 6.1 MPa. TheVickers's hardness level increased from 225 HV to 350 HV with increasing nitrogen content up to 4000 ppm. When the nitrogen content exceeded about 5000 ppm, grain boundary fracture was easily caused by Cr{sub}2N precipitation.