高碳高锰钢拉伸过程中应变硬化行为的研究

Strain Hardening Behavior of High Carbon and High Manganese Steel during Tensile Process

采用金相组织分析、拉伸性能测试和透射电镜分析等方法,研究了高碳高锰钢拉伸过程中的应变硬化行为.结果表明,高锰钢980℃水韧处理后获得了晶粒平均尺寸为89.7μm的单相奥氏体组织.其在拉伸曲线上表现出了典型的双n应变硬化行为,应变硬化指数依次为0.618和0.832.同时在应变硬化率曲线上具有明显的锯齿形貌,且不同的应变阶段锯齿的波动程度不同:低应变量阶段时,锯齿的波动程度较为稳定,其锯齿高度差约为31.1 MPa;中应变量阶段时,锯齿的波动程度随应变量增加而明显增加;高应变量阶段时,锯齿的波动程度重新趋于稳定,其锯齿高度差达到最大,约为1 407.2 MPa.在整个塑性变形过程中,位错滑移和孪生变形先后主导高锰钢的变形机制,这是导致高锰钢在不同应变阶段表现出不同应变硬化行为的主要原因.

The strain hardening behavior of a high carbon high manganese steel during tensile process was studied by means of OM analysis,tensile test and TEM analysis.The results show that for the high manganese steel,the microstructure with full austenite of an average grain size of 89.7μm can be obtained after 980°C water toughening treatment.It exhibits a typical double n strain hardening behavior on the tensile curve,and the strain hardening index is 0.618 and 0.832,respectively.There are obvious sawtooth morphology on the strain hardening rate curve,and the fluctuation degree of the sawtooth is different in different strain stages.In low strain stage,the fluctuation degree of the sawtooth is relatively stable,and the sawtooth height is about 31.1 MPa.In medium strain stage,the fluctuation degree of the sawtooth increases significantly with the increase of strain.In high strain stage,the fluctuation of the sawtooth tends to be stable again,and the sawtooth height reaches the maximum,about 1407.2 MPa.During the whole plastic deformation process,dislocation slip and twin deformation dominate the deformation mechanism of the high manganese steel successively,which is the main reason for the high strain hardening behavior of the high manganese steel in different strain stages.