Effect of Austenitizing Temperatures on the Mechanical Properties in 420J2 Martensitic Stainless Steel

420J2 마르텐사이트계 스테인레스강의 오스테나이트화 온도가 기계적 성질에 미치는 영향

For the purpose of investigating the effect of austenitizing temperatures on the mechanical properties of 0.23% C-13.6%Cr martensitic stainless steel, tensile properties, hardness, impact value and carbide extraction were examined after changing the austenitizing temperatures and tempering temperatures. The results obtained are summerized as follows. The carbide laminations formed from hot rolling before austenitization could not be eliminated after austenitizing at $950^{\circ}C$. With increasing austenitizing temperature, hardness increased and showed maximum value at $1050^{\circ}C$ and then slightly decreased. With increasing tempering temperature up to $500^{\circ}C$, impact value and elongation appeard to be decreased but hardness showed nearly unchanged at austenitizing temperature of $1150^{\circ}C$ due to the fine $M_7C_3$ carbides precipitation. The abrupt increase in impact value, hardness and elongation above the tempering temperature of $500^{\circ}C$ appeared to change in carbide structure from fine $M_7C_3$ to coarse $M_{23}C_6$.