Use of EBSD technique to examine microstructure and cracking in a bainitic steel

This paper investigated the effects of welding and alternating wet-dry seawater on the hydrogen embrittlement (HE) susceptibility of a new nanoparticle-reinforced high-strength steel, dispersion-strengthened-high-strength (DSHS) steel. The results show that welding led to the transformation of granular bainite to tempered martensite. It also promotes grain coarsening as well as an increase in inclusions size and irregular changes in shape. This results in increased susceptibility to HE at the welded joint (WJ). After wet-dry cycle corrosion in seawater, corrosion products impede the oxygen transfer and promote the hydrogen evolution reaction, so the hydrogen production increases. The decrease in the protection of corrosion products at the WJ and the decrease in NbC content led to an increase in hydrogen production but a decrease in hydrogen trapping capacity. Therefore, the WJ HE sensitivity of DSHS steel is further increased.