Preliminary study on pulsed current treatment of preset cracks in 2A12 aluminum alloy

Repairing tests of preset cracks in 2A12 aluminum alloy were carried out by pulsed current in this paper. Microstructure of specimens before and after pulsed current treatment were observed, and effects of pulsed current on hardness and tensile strength of specimens were tested. The results showed that it tended to heal preset cracks when peak currents were 295 A, 410 A and 656 A, electrifying times were 1.5 s, 1.5 s and 2.25 s respectively, and voltage was 4 V. When pulsed current was 410 A peak current, it had the best cracks healing effect, and grains around the crack tip were refined. Average micro-hardness of specimens before and after pulsed current treatment approached 130 HV and 125 HV, respectively. Joule heating effect of pulsed current at the crack tip zone promoted aluminum alloy to recover and recrystallize, internal stress was eliminated, and micro-hardness decreased. Average tensile strength of specimens before and after pulsed current treatment were 273 MPa and 281.7 MPa, respectively. High-density pulsed current at crack zone accelerated movement of dislocations and increased tensile strength by 3.19%. UN1-1 butt welding machine with simple parameter regulation was used as pulsed current treatment power source in this paper. Hammering method was used to preset cracks. The obtained cracks were closer to the actual cracks. Feasibility of pulsed current repairing cracks of 2A12 aluminum alloy was verified.Highlights: (1) Preset cracks obtained by hammering method were closer to the actual cracks.(2) UN1-1 butt welding machine was used as pulsed current treatment power source to verify feasibility of pulsed current repairing cracks of 2A12 aluminum alloy.