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用拉伸试验对4043和2024 T4铝合金造成损伤和冷加工硬化,施加的应力处于屈服强度和抗拉强度之间。2024 T4铝合金在225MPa下循环到其半寿命(85 000次)造成疲劳损伤。被损伤的试件用直流电脉冲处理。用电桥分别测量原始试件、损伤试件和电脉冲处理试件的电阻。结果表明,随着脉冲处理时间的增加,4043铝合金拉伸造成损伤的试件延伸率增加,屈服强度和抗拉强度减小;0.5 s脉冲处理试样的力学性能十分接近未损伤试样的性能。2024 T4铝合金的疲劳损伤试件经0.8s电脉冲处理后的寿命显著提高。经过疲劳或拉伸损伤的铝合金电阻明显增加,再经电脉冲处理后电阻减小,但是其电阻仍高于原始试件。处理时间对最终的电阻值影响很小,但是力学性能随处理的时间不同差别很大。虽然电阻可描述铝合金的损伤,但是它对力学性能不十分敏感,因此电阻不是一个很好的表证损伤愈合的方法。组织观察显示,经过电脉冲处理后损伤得到部分愈合,并存在再结晶现象。
Tensile tests were used to damaging and cold work harden the 4043 and 2024 T4 aluminum alloys with the applied stress between yield strength and tensile strength. 2024 T4 aluminum alloy cycles to its half life (85 000 cycles) at 225 MPa resulting in fatigue damage. Damaged specimens were treated with DC pulses. The electrical resistance of the original specimen, the damage specimen and the electric pulse treatment specimen were respectively measured by electric bridges. The results show that with the increase of pulse processing time, the tensile elongation of 4043 aluminum alloy increases and the yield strength and tensile strength decrease. The mechanical properties of 0.5s pulse processing sample are very close to that of the uninjured performance. The fatigue life of 2024 T4 aluminum alloy after 0.8s electrical pulse treatment significantly increased the life expectancy. After fatigue or tensile damage of the aluminum alloy resistance increased significantly, and then by the electrical pulse resistance decreases, but its resistance is still higher than the original specimen. The treatment time has little effect on the final resistance value, but the mechanical properties vary widely with the time of treatment. Although the resistance describes the damage of the aluminum alloy, it is not very sensitive to the mechanical properties, so the resistance is not a good way to show the healing of the damage. Tissue observations showed that after electrical pulse treatment, the lesions were partly healed and there was recrystallization.