The Influence of Stress Relieving on Microstructures and Mechanical Properties of Weld Metal in 60kg/mm² Quenched and Tempered High Strength Steel

응력제거 열처리가 60kg/mm²급 조질 고장력강의 용접부 미세조직과 기계적 특성에 미치는 영향

For the purpose of studying the influence of stress relieving on microstructures and mechanical properties of weld metal, manual arc welding, onepole and twopole submerged arc welding were accomplished on $60kg/mm^2$ quenched and tempered high strength steel. After stress relieving, a lot of carbides were precipitated, developed and subsequently coarsened at the grain boundaries and within matrix due tn multiple tempering effect in manual arc welding, resulting in deterioated toughness. Meanwhile pearlite and cementite films were spheroidized and shortened in submerged arc welding, resulting in improved considerable toughness. It was observed that main effect of stress relieving was to reduce solut supersaturation by nucleation and growth of carbide precipitates, and stress relieving led to some reduction in the yield and tensile strenath but did not significantly affect elongation.