(1. 中南大学 材料科学与工程学院，长沙 410083；
2. 有研亿金新材料有限公司，北京 102200)
摘 要: 沿冷轧纯铜板材法向取帽型试样，通过分离式霍普金森压杆(SHPB)进行动态剪切试验，借助光学显微镜(OM)、电子背散射衍射(EBSD)以及透射电子显微镜(TEM)分析手段，研究不同变形程度下冷轧纯铜的绝热剪切行为特征。结果表明：随应变率增大，试样对应峰值应力和流变应力增加，应变率硬化效应更为明显。不同应变量的试样均形成了绝热剪切带(ASB)，且剪切带宽度的变化趋势一致；随应变量增加，过渡区的应变梯度增大，剪切带内形成了超细晶。剪切带内晶体 方向趋向于平行宏观剪切方向，晶体 {111}面和{100}面趋向于平行宏观剪切面。基于旋转动态再结晶(RDR)机制，理论计算结果证实剪切带内发生再结晶的热动力学可行性。动力学计算结果表明，超细晶在变形后的冷却阶段没有发生明显长大。
关键字: 绝热剪切带；冷轧纯铜；微观组织；微观织构；旋转动态再结晶
（1. School of Materials Science and Engineering, Central South University, Changsha 410083, China;
2. GriKin Advanced Materials Co., Ltd., Beijing 102200, China）
Abstract:The hat-shaped specimens were prepared along the normal direction (ND) of the cold-rolled pure copper sheet. The dynamical shear test was conducted by the Split-Hopkinson pressure bar (SHPB). The adiabatic shear behaviors of cold rolled pure copper under different deformation degrees were systemically investigated by optical microscopy (OM), electron backscatter diffractometry (EBSD) and transmission electron microscopy (TEM). The results show that with the increase of strain rate, the peak stress and flow stress of corresponding to sample increase, and the strain rate hardening effect becomes more obvious. The adiabatic shear band (ASB) forms in the samples with different strains, and the change trend of the width of ASB is consistent. With the increase of strain, the strain gradient of transition region increases and ultrafine grains form within the ASB. The stable grain orientations, in which the crystal direction tends to align with the local shear direction and the crystal {111} and {100} planes tend to parallel to the local shear plane, develop in the ASB areas. The thermodynamics and kinetics calculated results prove the possibility that the dynamic recrystallization can take place in shear bands based on the rotational dynamic recrystallization mechanism. Kinetic calculations indicate that ultrafine grains do not undergo significant growth during cooling stage after deformation.
Key words: adiabatic shear band; cold-rolled pure copper; microstructure; microtexture; rotational dynamic recrystallization
