Microstructural analysis of edge cracking in magnesium alloy sheet under rolling

Abstract

Magnesium alloy sheet is prone to edge cracking during rolling. We carry out a microstructural analysis for edge cracks in Mg sheet under multiple rolling passes and different temperatures, where the microstructure, hardness and crystal orientation are explored and compared at the edge and middle of the specimen. The results indicate that the cracks are likely initiated from the edge due to coarsened grains, less basal texture and severe damage. A grain band with very fine grains is developed along the crack propagation path owing to the recrystallisation that takes place at the plastic zone in front of the crack tip. A rolling map is also obtained, which may help to guide the edge crack free rolling of Mg sheet.