Characterization of an HY-130 steel weldment by transmission electron microscopy.

Abstract

A wrought HY-130 steel weldment was studied to provide information about metallurgical differences in the weld heat affected zone (HAZ). Three GMAW welded areas were mapped and analyzed: heavily tempered, moderately tempered and untempered regions. Transverse sections were cut along the weld HAZ and the section microhardness compared with a previous microhardness traverse across the region to determine the location within the HAZ. Transmission electron microscopy revealed the occurrence of significant metallurgical changes from the fusion line to the HAZ/base metal interface. Microstructures were found to be similar to those of a low carbon steel, changing from a fine lath martensite at the HAZ/base metal interface to a mixture of upper bainite and fine lath martensite in the HAZ near the fusion line and finally to lower (acicular) bainite in the weld metal.