• Journal of Welding and Joining
• /
• 제11권4호
• /
• pp.79-90
• /
• 1993

Shielded metal arc welding, one-ploe and two-pole submerged arc welding were accomplished to investigate microstructure changes on phase transformation behavior in $60kg/mm^2$ quenched and tempered high strength steel. Microstructures were examined by optical micrograph and TEM. In shielded metal arc welding (oxygen 250ppm), the inclusions were small size (0.3-0.5$\mu\textrm{m}$)and small in number. In submerged arc welding (oxygen 430-529ppm), the inclusions were larger(0.7-2$\mu\textrm{m}$) than that of shielded metal arc welding and large in number. Microstructure mainly depends on number and distribution of inclusions in fusion zone of weld metal. It was noticed that a limited number of inclusions favors the formation of acicular ferrite.