Modulation of Heat-Affected Zone Toughness in High-Heat-Input Welded Eh47 Shipbuilding Steel Via Specific Misorientation Angles

Abstract

The important role of specific misorientation angle (SMA) on the impact toughness of coarse grain heat affected zone (CGHAZ) of shipbuilding steel was investigated from the perspective of crystal structure. The crystallography of microstructure formed was studied using the electron backscattered diffraction (EBSD) technique. It is found that overall misorientation angle (OMA) cannot explain the difference in the CGHAZ toughness, while SMA is close related with the CGHAZ toughness. The density of SMA between {100}-planes can be effectively increased by V(C, N), while that between {110}-planes is unaffected. According to the quantitatively counted SMA, the specimen with higher toughness exhibited higher density of boundaries with SMA between {100}-planes. The CGHAZ toughness can be improved by increasing density of {100}-SMA, thereby improving the welding effect of shipbuilding steel.

Keywords: Grain boundaries, Microstructure, Toughness, shipbuilding steel, Misorientation