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直流脉冲电流对铝合金的损伤修复和电阻评估
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Damage Healing of Aluminum Alloys by D. C. Electropulsing and Evaluation by Resistance
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    摘要:

    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225 MPa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。

    Abstract:

    The damage and cold work hardening of 4043 and 2024 T4 aluminum alloy were introduced by tensile test under the applied stress between the yield strength and ultimate tensile strength. Fatigue damage of 2024 T4 aluminum alloy was introduced by cycling to half of fatigue life (85 000 cycles) at 225 MPa. Then the damaged specimens were healed by D. C. electropulsing. The electric resistances of as-received, damaged and healed specimens were measured by electric bridge, respectively. The results show that the elongation increases, and yield strength and ultimate strength decrease with the increase of healing time for the 4043 aluminum alloy tensile damaged specimen. The mechanical properties of the 4043 aluminum alloy damaged specimens treated by a 0.5 s electropulsing are close to the values of undamaged specimens. Fatigue life is considerably prolonged by a 0.8 s electropulsing treatment for the fatigue damaged specimen of 2024 T4 aluminum alloy. The electric resistance of aluminum alloys increases obviously after fatigue or tension damage, and decreases after electropulsing treatment, but it is still larger than that of the as-received specimen. The treatment time has little influence on the final resistances, but the mechanical properties are quite different for the samples treated by various electropulsing time. Although the resistance can describe the damage of aluminum alloys, it is not very sensitive to the mechanical properties, so it can not be considered as a good criterion for healing evaluation. The observation of microstructure reveals that the damages can be partly healed after D. C. electropulsing, and recrystallizaton phenomenon appears.

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乔生儒,李艳丽,李 云,张程煜.直流脉冲电流对铝合金的损伤修复和电阻评估[J].稀有金属材料与工程,2009,38(4):570~573.[Qiao Shengru, Li Yanli, Li Yun, Zhang Chengyu. Damage Healing of Aluminum Alloys by D. C. Electropulsing and Evaluation by Resistance[J]. Rare Metal Materials and Engineering,2009,38(4):570~573.]
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  • 收稿日期:2008-03-17
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