淬火温度对30Cr2Ni4MoV钢组织和性能的影响

Effect of Austenitizing Temperatures on Microstructure and Mechanical Property of 30Cr2Ni4MoV Steel

为了解淬火温度对30Cr2Ni4MoV钢显微组织和力学性能的影响,对尺寸为φ100 mm×200 mm的试棒分别从780℃、820℃和860℃油淬随后640℃回火,检测了钢的显微组织和力学性能。结果表明:①不同温度淬火随后回火的30Cr2Ni4MoV钢的组织均为回火索氏体和残留奥氏体;②较低温度淬火、640℃回火的钢,马氏体呈条带状;③随着淬火温度的提高,钢的组织逐渐均匀化,由条带状转变成等轴状,其硬度和强度增加,冲击吸收能量下降。此外,扫描电镜检验表明,经调质处理的30Cr2Ni4MoV钢冲击试样断口有大量的韧窝,也有细小撕裂棱,基本为韧性断裂。

30Cr2Ni4MoV steel test bar 100 mm in diameter by 200 mm long was quenched respectively from 780,820,and 860℃in oil then tempered at 640℃,then tested for microstructure and mechanical properties for the purpose of discovering effect of austenitizing temperatures on microstructure and mechanical properties of 30Cr2Ni4MoV steel.The results are that:① the microstructures of 30Cr2Ni4MoV steel quenched from different temperatures then tempered all were tempered sorbite and retained austenite;②the steel quenched from lower temperature and tempered at 640℃ exhibited strip-like martensite;and③as the austenitizing temperature increased,the steel exhibited more uniform microstructure whose shape changed from strip-like to equiaxed,was even higher in both hardness and strength and even lower in impact absorption energy.Besides,from examination by scanning electron microscope it was seen that fracture of impact test specimen of the quenched-and-tempered 30Cr2Ni4 MoV steel presented a large number of dimples and fine tearing ridges,basically being ductile fracture.