Influence of post-weld heat treatments on microstructure and mechanical properties of AISI 431 martensitic stainless steel friction welds

Abstract

The relative effects of different post-weld heat treatments (PWHTs) on microstructure and mechanical properties of friction welded martensitic stainless steel type AISI 431 were studied. The weld microstructure consists of acicular martensite in equiaxed prior austenite grains and with heat treatment, the martensitic microstructure experiences coarsening. It was observed that retained austenite content decreases with an increase in the PWHT tempering temperature. The tensile properties of welds under different PWHTs were comparable to those of parent metal in the respective treatments. Welds exhibited higher notch tensile strengths than the parent metal in the respective heat treatment condition. Double tempering (670°C + 600°C) led to maximum reduction in hardness. Welds exhibited poor impact toughness in the as welded condition. The improvement in impact toughness was found satisfactory in welds subjected to double tempering, although did not match to the level of the parent metal at respective conditions. The mechanism and reasons for the observed behaviour have been discussed, correlating the microstructure, fracture features and mechanical properties.

Influence of austenitizing temperature on microstructure and mechanical properties of AISI 431 martensitic stainless steel electron beam welds

“…15). These observations are in conformity with similar trends reported in steels and titanium alloys [22][23][24]. Lower toughness of welds as compared to the parent metal could be due to presence of less number of martensite colonies that contribute to crack path deviation.…”

The effect of post-weld heat treatments on the microstructure and mechanical properties of maraging steel laser weldments

“…18). These observations are in conformity with similar trends reported in steels and titanium alloys [19,20]. The present observations suggest that post-weld homogenization treatment that results in elimination of micro-segregation leading to elimination of reverted austenite is required to improve the impact toughness of welds.…”

Influence of heat treatment on friction-welded joints made of high-carbon high-chromium tool steel/low-carbon steel for tooling applications

“…and increase toughness. Either annealing and normalizing or tempering has been tried by many researchers [4][5][6][7][8].…”

“…In the studies by Raja Sekhar [4], friction-welded component of AISI 431 martensitic stainless was post-tempered at 400 °C and it is reported that martensitic microstructure got coarsened which resulted in high strength and hardness but the poor impact toughness. Emre and Kacar [5] conducted friction welding studies with pipes made of N80 and 42CrMo4 steels and recommended annealing at 600 °C for 20 min.…”