Q&P工艺对5CrMnNiMo超高强度钢组织及性能的影响

Effect of Q&P process on microstructure and properties of 5CrMnNiMo ultra-high strength steel

对5CrMnNiMo超高强度钢进行了淬火-配分(Q&P)处理,利用SEM、电子万能试验机、X射线衍射仪、EBSD等试验手段,探讨了试验钢的显微组织和力学性能随Q&P工艺中等温配分5 min、24 h及非等温配分6 h后的变化规律。结果表明,Q&P处理过程中,显微组织均由马氏体+残留奥氏体+少量粒状碳化物组成,随着等温配分时间的延长,残留奥氏体由片状逐渐转变为块状;等温配分5 min后,获得高达2230 MPa的超高抗拉强度,抗拉强度经等温配分24 h后降低到1360 MPa;塑性变形量由等温配分5 min后的3.92%增加到非等温配分6 h后的14.62%,TRIP效应是塑性变形量增加的主要原因。

Quenching and partitioning(Q&P) process was performed for 5 CrMnNiMo ultra-high strength steel. The changes of microstructure and mechanical properties of the tested steel with isothermal partitioning for 5 min, 24 h and non-isothermal partitioning for 6 h under Q&P process were investigated by means of SEM, electronic universal testing machine, X-ray diffraction and EBSD. The results show that during Q&P treatment, the microstructure is composed of martensite, retained austenite and a small amount of granular carbide. The retained austenite gradually transforms from flake to block with the prolongation of isothermal partitioning time. After isothermal partitioning for 5 min, the ultra-high tensile strength of 2230 MPa is obtained. The tensile strength is decreased to 1360 MPa after isothermal partitioning for 24 h and the plastic deformation is increased from 3.92%(isothermal partitioning time of 5 min) to 14.62%(non-isothermal partitioning time of 6 h). The TRIP effect is the main reason for the increase of plastic deformation.