THE TEMPERING MICROSTRUCTURES IN STE355 STEELS AFTER SIMULATED WELD THERMAL CYCLE

The effects of tempering temperature on microstructures in STE355 steels after welding has been investigated. The simulated weld HAZ specimens were produced by applying single-pass and multi-pass welding thermal cycle respectively with a peak temperature of 1320℃.then were tempered by soaking for 1. 5 hours at 500-620℃ The microstructure changes in specimens,especially the decomposition and transformation of granular bainite and M-A constituent at different tempering temperature were observed by scanning and transmission electron microscopes. The relative proper tempering process was proposed according to the relation between microstructure and properties.