(1. 中南大學(xué) 材料科學(xué)與工程學(xué)院，長沙 410083；
2. 有研億金新材料有限公司，北京 102200)
摘 要: 沿冷軋純銅板材法向取帽型試樣，通過分離式霍普金森壓桿(SHPB)進(jìn)行動(dòng)態(tài)剪切試驗(yàn)，借助光學(xué)顯微鏡(OM)、電子背散射衍射(EBSD)以及透射電子顯微鏡(TEM)分析手段，研究不同變形程度下冷軋純銅的絕熱剪切行為特征。結(jié)果表明：隨應(yīng)變率增大，試樣對(duì)應(yīng)峰值應(yīng)力和流變應(yīng)力增加，應(yīng)變率硬化效應(yīng)更為明顯。不同應(yīng)變量的試樣均形成了絕熱剪切帶(ASB)，且剪切帶寬度的變化趨勢一致；隨應(yīng)變量增加，過渡區(qū)的應(yīng)變梯度增大，剪切帶內(nèi)形成了超細(xì)晶。剪切帶內(nèi)晶體 方向趨向于平行宏觀剪切方向，晶體 {111}面和{100}面趨向于平行宏觀剪切面。基于旋轉(zhuǎn)動(dòng)態(tài)再結(jié)晶(RDR)機(jī)制，理論計(jì)算結(jié)果證實(shí)剪切帶內(nèi)發(fā)生再結(jié)晶的熱動(dòng)力學(xué)可行性。動(dòng)力學(xué)計(jì)算結(jié)果表明，超細(xì)晶在變形后的冷卻階段沒有發(fā)生明顯長大。
關(guān)鍵字: 絕熱剪切帶；冷軋純銅；微觀組織；微觀織構(gòu)；旋轉(zhuǎn)動(dòng)態(tài)再結(jié)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
