高锰钢高速冲击时剪切区TRIP行为的准原位分析  

Quasi-in-situ analysis of TRIP behaviors in shear zones of high-manganese steel specimen under dynamic compression

作　　者：林颖 王强[1] 杨平[1] LIN Ying;WANG Qiang;YANG Ping(School of Materials Science and Engineering,University of Science and Technology Beijing, Beijing 100083, China)

机构地区：[1]北京科技大学材料科学与工程学院

出　　处：《工程科学学报》2018年第6期703-713,共11页Chinese Journal of Engineering

基　　金：国家自然科学基金资助项目(51271028)

摘　　要：利用背散射电子衍射技术对高速冲击前后高锰钢样品强制剪切区域的晶粒进行准原位观察,分析了剪切区域不同位置晶粒的相变情况,并借助有限元模拟及受力计算对不同晶粒相变程度差异的原因做了进一步分析.结果表明,在高速变形下,应力应变水平、奥氏体取向及晶粒间的相互作用共同影响TRIP行为：应力应变水平越高,相变程度越大;由于帽型样中剪切应力的存在,相比于近〈111〉取向奥氏体,近〈100〉和近〈110〉取向奥氏体相变程度更大,近〈110〉取向相变程度最大.具有有利取向的奥氏体,晶粒尺寸越大,其相变行为受周围晶粒影响越小,越容易充分相变;具有有利取向的长条状奥氏体晶粒,若其两侧晶粒难相变,则该晶粒相变将受到束缚;带有尖角的晶粒,变形时应力集中难以释放,易发生相变;当晶粒的孪生分力大于滑移,但其最大和次大的孪生分力相差不大,可能导致在这两个方向孪生互相竞争,反而不易相变.高速变形时体心马氏体多在晶界应力集中处产生,很少在晶粒内部大量产生,形态多为细片状,变体选择强.Owing to martensitic transformation during deformation,high-manganese transformation-induced plasticity（ TRIP）steels show an excellent combination of strength and ductility. They are considered as second-generation automobile steels. Because of the influence of strain rate,the TRIP behaviors of high-manganese steels may be different during dynamic and static compressions.Therefore,it is necessary to study the TRIP behaviors during dynamic deformation. Based on the research on the TRIP behaviors of high-manganese steel at low strain rates,in this study,the TRIP behaviors were evaluated at high strain rates. Given the special shape of hat-shaped specimen and fixed position of shear zone,the grains present in the shear zone of high-manganese steel before and after dynamic compression were quasi-in-situ characterized using the electron backscattering diffraction（ EBSD） technique. Besides,the phase distribution of grains in different locations of shear zone was analyzed. In addition,finite-element simulations and stress calculations were conducted using the ANSYS/LS-DYNA and MATLAB softwares,respectively,to further analyze the differences in the phase transformation of each grain. The results show that the combined action of stress and strain,orientation of austenite,and the interactions among grains influences the TRIP behaviors. The higher the stress and strain the easier the phase transformation. Because of the existence of shear stress in hat-shaped specimens,phase transformation is more likely to occur in austenite with orientation along〈100〉and 〈110〉than austenite with orientation along 〈111〉,and phase transformation is most likely to occur in austenite with orientation along 〈110〉. Moreover,the phase transformation behavior of austenite with a favorable orientation and large grain size will be less af-fected by neighboring grains and easier to achieve a complete phase transformation. However,the phase transformation of striped grains with a beneficial orientation will be constrained when

关 键 词：高锰钢 高速冲击 TRIP行为 准原位分析 有限元模拟 

分 类 号：TG142.3[一般工业技术—材料科学与工程]