砷对45钢组织及力学性能的影响

Effect of arsenic on microstructure and mechanical properties of 45 steel

采用膨胀法、金相法研究了不同As含量45钢的过冷奥氏体连续冷却转变过程,分析了45钢在不同冷速下过冷奥氏体的组织转变,测定了试验钢的室温抗拉强度与冲击功,并利用扫描电镜(SEM)观察了断口形貌。研究结果表明,随砷含量的增加,45钢组织中的铁素体含量增加,且较易形成晶内铁素体;砷的加入缩短了贝氏体转变的孕育期,使45钢的过冷奥氏体连续冷却转变曲线明显左移,其M s点温度随砷含量的增加依次下降;砷含量<0.25%时,对45钢强度与韧性的影响并不明显。

The continuous cooling transformation curves for 45 steels with varied contents of arsenic were examined by use of thermal dilatometer and metallography.And the microstructure obtained at different cooling rates was analyzed.The room temperature tensile strength and the impact energy of the tested steels were measured and the fractography was observed using SEM.The results show that the ferrite contents increase and the intragranular ferrite phase is easily formed with the increase of amount of As in 45 steel.The addition of As shortens the incubation period of bainite transformation and makes the CCT curve of 45 steel shift to left.At the same time,Ms point is decreased by increasing the As content.When the As content is less than 0.25%,arsenic has no significant effect on the strength and toughness of 45 steel.