单晶铜的包申格效应

Bauschinger Effects in Single Crystal Copper

单晶铜在实际应用时需经过多次塑性变形,将导致包申格效应的产生,对其后续工艺和产品质量产生影响.对单晶铜在先压缩后拉伸时出现的包申格效应进行了研究,并与多晶铜进行了对比.实验结果表明:单晶铜和多晶铜在正反向加载时均出现包申格效应,在预应变相同的条件下,单晶铜的包申格效应不如多晶铜的显著.单晶铜的包申格效应随预压缩量的增加先增大后减小,在预压缩量为0.156%附近该效应最为显著.多晶铜的包申格效应在预压缩量小于0.2%时变化不明显,大于0.2%时随预压缩量的增加而增加.单晶铜中出现包申格效应的根本原因是反向加载时短程应力的释放,多晶铜中由于存在晶界引起的长程应力,在反向加载时该应力和短程应力同时释放,从而体现出更为显著的包申格效应.

The plastic.＇ deformation causes Bauschinger effect which affects subsequent procedure and performance of the single crystal copper （SCC）. In this paper,BE of SCC has been studied and compared with the poly-crystal copper（PCC）. The results show that both SCC and PCC have BE, BE of SCC is lower than that of PCC. BE of SCC increases with pre-strain increating, it reaches the maximum when the pre-strain equals to 0. 156%. If the pre-strain exceeds 0. 156%, BE decreases. BE of PCC changes unconspicuously when the pre-strain is less than 0.2%. If it exceeds 0. 2%,BE increases with pre-strain increating. The basic reason for BE existing in SCC is releasing of short-range stresses when the samples have been loaded in the opposite direction. The long-range stresses caused by grain boundaries in PCC release simutaniously, so that BE is more obvious.