新型700 MPa级高强锚杆钢的微观组织及强化机制

Microstructure and strengthening mechanism of a novel 700 MPa grade high strength anchor steel

自主设计了700 MPa级高强锚杆钢,采用光学显微镜、扫描电镜和透射电镜等对其微观组织与性能进行了系统测试与表征,并进一步讨论了其强化机制。结果表明,该锚杆用钢的显微组织为珠光体和铁素体复相组织,铁素体呈细小的等轴状,珠光体呈长条形片层状分布,组织中珠光体体积分数约为43%;铁素体基体上析出了大量小于20 nm的纳米级V(C,N)粒子;试验钢屈服强度约为734 MPa,抗拉强度约为936 MPa,断后伸长率约为15.1%,屈强比约为0.78,具有良好的综合性能;该锚杆钢的强化机制为细晶强化、固溶强化、位错强化及析出强化的耦合强化,其中,细晶强化及固溶强化引起的强度贡献约占总强度值的73%。

Microstructure and mechanical properties of a self-designed 700 MPa grade high strength anchor steel were investigated systematically by means of optical microscope,scanning electron microscope as well as transmission electron microscope,etc,and the strengthening mechanisms of the tested steel were further quantitatively discussed.The results show that the microstructure of the tested anchor steel is composed of banded laminated pearlite and fine equiaxed ferrite,the volume fraction of pearlite is about 43%,and in the ferrite there are a large amount of nano-sized V(C,N)precipitated particles(<20 nm).In addition,the tested steel has good comprehensive properties,with the yield strength,tensile strength,and elongation after fracture being respectively about 734 MPa,936 MPa,and 15.1%,and the yield ratio being about 0.78.The strengthening mechanism of the tested anchor steel is a coupling of grain refining strengthening,solid solution strengthening,dislocation strengthening,and precipitation strengthening,where the contributions induced by grain refining strengthening and solid solution strengthening account for about 73%of the total strength.