Cause Analysis on Heat Affected Zone Cracking of Weldments of 16MnD5 Steel

Cause analysis was conducted on the heat affected zone (HAZ) cracking of a high strength low alloy 16MnD5 steel plate weldment by the methods of chemical compositions analysis, macroscopic examination, metallographic examination and microhardness test. The results show that the crack began from the coarse grain zone of the HAZ, and extended in the mixed manner of intergranular and transgranular. The crack was cold crack which was mainly caused by residual stress and the base metal’s tendentiousness of harden quenching.