Combination of eddy current and heat treatment for crack healing and mechanical-property improvement in magnesium alloy tube

Abstract

The continuous eddy current pulse treatment (ECPT) combined with heat treatment was employed to heal the microcracks in spin formed Mg alloy tubes and improve their mechanical properties in this study. The results show that all the microcracks in different tube specimens were almost healed after different continuous ECPT schemes up to 15 cycles. The schemes with less cooling intervals exhibited better healing effect and increased the strength and elongation of Mg alloy tubes more obviously. After aging treatment, the strength improvement of the specimens with ECPT was more remarkable than that of the specimens without ECPT, and the elongation decrease of the specimens with ECPT was less evident than that of specimens without ECPT due to the segregation of RE elements on the crack surface. Besides, after solution treatment, the strength reduction and ductility improvement of the specimens with ECPT were more pronounced than that of the specimens without ECPT owing to the notable decrease of dislocation density of the specimens with ECPT. Both narrowed cracks induced by ECPT and the segregation of precipitates in the vicinity of microcrack surface during aging treatment contributed to the maximum strength in the as-spun specimens with ECPT followed by aging treatment.