淬火冷却规范对G50钢微观组织和力学性能的影响

借助转子钢冷却过程实测温度变化,制订了不同直径棒材心部冷却规范,研究了G50超高强度钢在奥氏体化后以不同冷却速度冷却后得到的微观组织及其力学性能。结果表明,等效ø430 mm和ø500 mm棒材轴心冷却试样形成马氏体+下贝氏体复相组织,抗拉强度高于油淬试样,屈服强度降低,但不明显损害冲击性能。等效ø650 mm棒材轴心淬火冷却形成60%以上的下贝氏体组织,进一步降低屈服强度的同时,冲击性能反而明显回升,表明该材料在较低的冷却速度下仍保有较高的韧性。

Effect of quenching specification on microstructure and mechanical properties of G50 steel

Core cooling specification of different diameter bars was formulated, based on the measured temperature change of rotor steel quenching process. The microstructure and mechanical properties of the G50 ultra-high strength steel after austenitizing and cooling at different cooling rates were studied. The results show that the cooling specimens equivalent ø430 mm and ø500 mm bars core form martensite and lower bainite complex structure, their tensile strength is higher than that of the oil quenched specimens, the yield strength is lower, but the impact property is not significantly affected. The core specimen equivalent ø650 mm rod forms more than 60% lower bainite, further reduces the yield strength, but obviously rises up the impact prooperty, showing that the steel can maintain high toughness in slower cooling rate.