直流脉冲电流对4043铝合金拉伸硬化的影响

低成本消除加工硬化,愈合损伤对轧制材料具有重要意义。本文将4043铝合金在介于其名义屈服强度和强度极限之间的某一应力下进行拉伸,造成拉伸硬化和损伤后,用直流脉冲电流处理。结果表明:随着脉冲处理时间的增加,试件延伸率增加,名义屈服强度和强度极限减小;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;光学显微照片显示同一位置上的损伤得到部分愈合。试样拉伸造成一定损伤后,其电阻值有明显增加;脉冲电流处理后电阻减小,但没有恢复到拉伸前的电阻值。经过不同时间的脉冲处理后,其电阻值十分接近,但是力学性能差异较大,表明电阻值对材料的力学性能不十分敏感,不能完全依赖电阻值判定材料的力学性能。

Effect of Electropulsing on the Tensile Hardening of 4043 Aluminum Alloy

Eliminating the work hardening and healing the damage with low cost are important for rolling materials.In this paper,pretensile tests are first performed to cause artificial damage and hardening of 4043 aluminum alloy with applied stress between the yield strength and ultimate strength.Then the specimens were treated by DC electropulsing.The results show that the elongation increases with the increase of treated time,whereas yield strength and ultimate strength decrease.The mechanical properties of specimens treated by a 0.5 s electropulsing approximate to those of undamaged specimens.The observation by an optical micrograph reveals that the damages have been healed.The electric resistance increases obviously after pretension,and decreases after the electropulsing treatment,but it is still larger than that before pretension. The treatment time has little influence on the resistances,but the mechanical properties are quite different from the samples treated by various electropulsing time.Therefore,the resistance is not sensitive to the mechanical properties, so it can not be considered as a criterion of the healing of the mechanical properties.