Weldability of High Nitrogen Austenitic Stainless Steel Reports 2 ---Nitrogen Absorption of 316L Weld Metal and Its fine particles in Extreme Environments---

摘要

The suitability of the high nitrogen pressure Metal Inert Gas (MIG) ARC welding process (constant arc length condition ) for high nitrogen containing stainless steel was investigated. The formation of fine stainless steel particles by the high nitrogen pressure MIG arc welding process was examined. The welding atmosphere consisted of pressurized N_2 gas. Nitrogen absorption of 316L stainless steel weld metal in the high nitrogen pressure MIG process was studied. The effect of nitrogen in remelted weld metal and changes in the microstructure of the weld metal were observed. The nitrogen content of weld metal and the number of fine particles increased with increasing pressure of N_2. Approximately 0.64 and 2.4 mass % nitrogen was absorbed in the weld metal and fine particles at pressure of N_2 6Mpa and 3Ma nitrogen respectively. Nitrogen content of the weld metal was lower than that representing equilibrium solubility of 316L stainless steel at close to the melting point. Nitride in the fine particles could not be found by X-ray analysis.