Mechanical Properties of High Nitrogen-Bearing Stainless Steel Friction Welds(Materials, Metallurgy & Weldability)
Friction welding of nitrogen-bearing stainless steels was carried out using a pressure servo-control system brake type device. The welding parameter settings comprised of rotational rate of 2400rpm, friction pressure of 70MPa for 4, 7, 10 and 15 seconds, and upset pressure of 150MPa for 6 seconds, respectively. As the friction time increased, the recrystallization zone (Region I) at the bondline vicinity increased. In contrast, increase in friction time decreased the region (Region II) where the grains were partly deformed and grown. TEM examination suggested that the intergranular phases precipitated at bondline vicinity are Cr_2N (Hexagonal, a=0.48113nm, c=0.44841nm) and CrN (Cubic, a=0.4140nm). Tensile test results indicated that nitrogen-bearing stainless steel joints have considerably higher tensile strengths than the commercial stainless steel SUS316L or SUS304 joints. However, for all welding conditions, the joint strength of high nitrogen containing-HNS-1 or HNS-2 joints showed slightly lower values than that of the base material. The inferior tensile strength of the nitrogen-bearing stainless steel joint could be due to Cr-nitrides precipitated near the bonding interface.
- Transactions of JWRI
Transactions of JWRI 29 (2), 59-65, 2000-12