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薄板试样在单轴拉伸时通常先形成扩散缩颈,继而形成与拉伸轴成约60°的集中缩颈,然后沿集中缩颈断裂。在我们的试验中,过时效状态的LC4铝合金薄板的形变断裂行为符合通常规律,而欠时效和某些峰值时效状态的LC4铝合金薄板在形成与拉伸轴成约60°的集中缩颈后,并不沿集中缩颈断裂,却沿与拉伸轴成90°的方向断裂,宏观断口与拉伸轴在厚度方向成45°。本文对这种现象进行了分析和讨论,并提出了可能的解释。
The sheet samples typically form a constricted neck during uniaxial stretching, which in turn creates a concentrated neck that forms an angle of about 60 ° with the stretching axis and then breaks along the neck. In our experiments, the LC4 aluminum alloy sheet in overetched state behaves in the same way as the general law of rupture, whereas the under-aged and some of the peak-aged LC4 aluminum alloy sheets are deformed during the formation of a concentrated neck of about 60 ° with the stretching axis After that, it did not fracture along the concentrated necking but ruptured along the direction of 90 ° with the stretching axis. The macroscopic fracture and the stretching axis were at 45 ° in the thickness direction. This article analyzes and discusses this phenomenon and suggests possible explanations.