TIG Welding of High Manganese Austenitic Steel for Super Cryogenic Application

In this paper,investigated the microstructure and cryogenic properties of TIG welding joints for 32Mn-7Cr-0.6Mo-0.3N austenitic steel by means of some methods such as metalography,scanning electron micro scope,X-ray diffractometer,hardness test,cryogenic tensile test and so on.The test results showed that the satisfied welded joints can be achieved using TIG welding of Argon and Nitrogen mixed protection.The joint microstructure is fine and homogeneous,and some welding defects such as crack and blowholes are not found.The 77 tensile fracture surfaces exhibit a tough character mainly composed of dimples.The decreasing of Nitrogen content in wended joints can be effectively suppressed by adding little Nitrogen into shielding gas,and better cryogenic strength of joint can be gained.The 77 tensile strength of smooth is about 1 150 MPa.The reasonable mixture rate of Nitrogen in shielded gas is 4%.The joint microstructure has high stability,and keep fully austenite phases in welds and HAZ after welding.