热轧+淬火配分处理对Q235钢组织及性能的影响

Effect of hot rolling+quenching and partitioning on microstructure and properties of Q235 steel

采用光学显微镜、扫描电镜、电子万能试验机、数显显微硬度计,研究了一步法淬火配分(Q&P)工艺和热轧一步法淬火配分(HR-Q&P)工艺在不同配分温度下处理后Q235钢的组织和力学性能。结果表明:HR-Q&P工艺使试验钢晶粒明显细化,显微组织由马氏体、铁素体和贝氏体组成,在350℃配分下,屈服强度和抗拉强度都达到最大值,分别为449 MPa和560 MPa,伸长率与原样相比下降了8%,但仍然超过30%;硬相的马氏体和贝氏体的同时出现,导致断口出现二次裂纹;一步法Q&P工艺下,与未处理试验钢相比,抗拉强度提高约32%,屈服强度提高近1倍,伸长率保持在26%以上。

Effect of partitioning temperature during one-step quenching and partitioning(Q&P)process and one-step hot rolling+quenching and partitioning(HR-Q&P)process on microstructure and mechanical properties of the Q235 steel was studied by means of optical microscope(OM),scanning electron microscope(SEM),electronic universal testing machine and digital microhardness tester.The results show that the grains of the tested steel are obviously refined by HR-Q&P process,and the microstructure is composed of martensite,ferrite and bainite.When partitioned at 350℃by HR-Q&P process,the yield strength and tensile strength of the steel reach the maximum,the values of which are 449 MPa and 560 MPa,respectively,while the elongation decreases by 8%compared with the as-received one,but still exceeds 30%.The hard phases of martensite and bainite appear at the same time during HR-Q&P process,resulting in secondary cracking.Under the one-step Q&P process,compared with the as-received tested steel,the tensile strength increases by about 32%,the yield strength increases by nearly one times,and the elongation remains above 26%.