Initiation and Suppression of Crack Propagation during Magnesium Alloy Rolling

Jing Tian,Jia-Fei Deng,Jin-Yao Ma,Wei Liang,Li-Xin Meng,Quan-Xin Shi

doi:10.3390/ma14185217

Abstract

The conventional rolling of magnesium alloy with a single pass and large reduction will cause severe edge cracking. The sheet without cracks can be achieved by limited width rolling. The microstructure evolution of the sheet with cracks after conventional rolling and the sheet without cracks after limited width rolling is explored, and an effective mechanism for solving edge cracks is proposed. Conventional rolling can fully develop twin evolution due to high deformation, and three stages of twinning evolution can be observed and the secondary twins easily become the nucleation points of micro cracks, resulting in a large number of cracks propagating along the twin lamellae. Cracks terminate at dislocation accumulation because the accumulation of a large number of dislocations can hinder propagation. Dislocation shearing of twins to eliminate the high localization caused by twins and induce the tensile twins to weaken the basal surface texture provides an effective plastic deformation mechanism of crack inhibition, which is useful for expanding the engineering application of magnesium alloy rolled sheets.

Highlights

IntroductionIt is easy to generate cracks at the edge of the magnesium alloy sheet during rolling and expand into the sheet
A commercial magnesium alloy sheet with a size of 70 mm × 60 mm × 3 mm is subjected to conventional rolling and limited width rolling in a single pass at 673 K and rolled to 1.5 mm, which is equivalent to the thickness reduction of
Crack propagation is due to the fact that conventional rolling will produce a large number of compressive twins and double twins under a large reduction in a single pass and cause a high degree of localization of the material strain, which becomes the nucleation point of microcracks, making the cracks spread along the twin lamellae and ends at the sheet where the dislocations accumulate

Summary

Introduction

It is easy to generate cracks at the edge of the magnesium alloy sheet during rolling and expand into the sheet. When rolling in a single pass with large thickness reduction, serious edge cracks will occur, failing to roll. Cutting off the edge cracks will result in low material utilization and higher costs. This hinders the rolling of magnesium alloys under a single pass with a large reduction. Rolling in multiple passes can obtain the magnesium alloy thin sheet with a large reduction thickness, the process is greatly increased. Solving the problem of edge cracks in magnesium alloy rolling with large thickness reduction and improve its formability is important

Methods

Results

Conclusion