弛豫时间对X100管线钢组织和力学性能的影响

Effects of Relaxation Time on Microstructure and Mechanical Properties of X100 Pipeline Steels

采用拉伸试验、冲击试验以及显微组织观察等方法研究了轧后弛豫时间对X100管线钢显微组织与力学性能的影响。结果表明:随着弛豫时间延长,贝氏体铁素体板条变宽,板条内部位错密度降低,碳氮化物析出量增多,屈服强度呈现先减小后增大的趋势,抗拉强度缓慢增加,屈强比与断后伸长率先降低后升高然后再降低,-20℃下的冲击功先升高后降低;弛豫时间为52s时能够获得较高的强度、韧性和均匀伸长率,可满足X100管线钢抗大变形的要求。

The effects of relaxation time after rolling on microstructure and mechanical properties of X100 pipeline steel by tensile testing,impacting testing and microstructure observing.The results show that with the prolongation of relaxation time,the bainite ferrite laths became wide and dislocation density inside laths reduced,the volume of carbonitride precipitation increased,the yield strength firstly decreased and then increased,the tensile strength increased slowly,the yield ratio and elongation after fracture decreased firstly,then increased and then decreased,and the impact energy at-20 ℃ increased firstly and then decreased.When the relaxation time was52 s,higher strength,higher toughness and uniform elongation were achieved,those could meet the demands of large deformation of X100 pipeline steel.