Characterization of preheated and non-preheated HY-80 steel weldments by transmission electron microscopy

Abstract

Preheating HY-80 steel weldments is standard procedure, but it is an expensive and time consuming step in the fabrication of hull structures. The microstructures and hardness profiles of both a preheated (250 F--121 C) and a non-preheated (32 F--0 C) HY-80 steel weldment were studied to provide information and allow comparisons of the microstructural transformations that occur in the heat affected zone during shielded metal arc welding. Optical, scanning electron and transmission electron microscopy were utilized to characterize the microstructure within the heat affected zone of each weldment. The only significant difference observed was that preheating reduced the amount of transformation twinned martensite found in the weld heat affected zone which may reduce the susceptibility to hydrogen induced cold cracking.