Approved for public release; distribution is unlimited / HY-130 is a high-strength, low-carbon steel used in the quenched and tempered condition . It is designed for high performance and marine applications where good weldability is a requirement. Optimum welding parameters are currently under investigation. In this study, 1/2 inch (12.7 mm) HY-130 steel weldments produced by submerged arc welding (SAW) and gas metal arc welding (GMAW) processes are compared by means of a systematic microstructural characterization of the base metal, weld metal, and heat affected zone (HAZ). The microstructures are characterized by optical and electron micro­scopy and microhardness measurements are performed in the weld metal and across the HAZ to relate the microstructure with the microhardness profiles. The weld metal microstructure of both weldments showed a predominantly martensitic structure. The GMAW weld metal had a finer lath martensite structure and contained more retained austenite and twinned martensite. The SAW weld metal had a less defined lath structure which was more bainitic. The microhardness values were higher in the GMAW weld metal. No significant differences in microstructure and hardness were observed in the HAZ of the two weldments. / http://archive.org/details/effectofweldingp00mcnu / Captain, Canadian Forces