In situ observation and electron backscattered diffraction analysis of granular bainite in simulated heat-affected zone of high-strength low-alloy steel

摘要

In this study, the formation of granular bainite (GB) which may form in the heat-affected zoneof double-sided double arc welding joint was in situ observed. The crystallographic characteristicsof GB were also compared with those of microstructure mainly comprising lath bainite (LB).The results show that bainite packets exist at the initial stage of GB transformation and can bedistinguished by the distribution of retained austenite and martensite–austenite constituents.The bainite blocks of GB are larger than those of LB which makes both the length and fractionof high-angle grain boundaries in GB less than those of LB which partly lead to the brittleness ofgranular bainite.