Influence of Grain Size and Texture on the Yield Strength of Mg Alloys Processed by Severe Plastic Deformation

Jinbao Lin,Yongjun Chen,Lifeng Ma,Qudong Wang,Weijie Ren

doi:10.1155/2014/356572

Abstract

Severe plastic deformation (SPD) has been widely employed to refine the grain size of Mg alloys, with the main objective to improve the strength and ductility of Mg alloys, since the well-known Hall-Petch equation suggests that a decreased grain size leads to an increased yield strength. However, the yield strength of Mg alloys processed by SPD is often decreased even though the grain size is effectively reduced. The abnormal flow behavior in Mg alloys processed by SPD has attracted great attention although this mechanism is still unclear, due to its complex and extensive influence factors. In this paper, the relationships between the processing conditions, grain refinement, and mechanical properties of the SPD treated Mg alloys are reviewed, with the emphasis on the effects of grain size and texture on the yield strength.

Highlights

The use of magnesium alloys in industrial fields, such as the automotive and bicycle industries, has gained much attention due to their energy-efficient properties which include low density and high specific strength
It can be seen that almost all ECAP processed (ECAPed) and CEC processed (CECed) Mg alloys exhibit a decrease in yield strength, especially in the early stage of equal channel angular pressing (ECAP) and cyclic extrusion and compression (CEC) deformation
The standard positive strength dependence on the grain size for Mg alloys, with the similar texture, supports that the softening of SPD processed (SPDed) Mg alloys which are typically observed despite the significant grain refinement, is due to the texture modification where the rotation of basal planes occurs towards the orientation for easier slip [21]

Summary

Introduction

The use of magnesium alloys in industrial fields, such as the automotive and bicycle industries, has gained much attention due to their energy-efficient properties which include low density and high specific strength. CEC seems to be more promising for industrial applications due to its continuous process It is very suitable for refining grains of hard-to-deform metals, for example, magnesium alloys, since it imposes threedimensional compression stresses during processing [10]. Researchers still report an increase in yield strength of fine-grained Mg alloys processed by ECAP and CEC [13, 24,25,26,27,28,29,30,31,32] These discrepancies indicate that the effects of ECAP. The relationships among the processing conditions, grain refinement, and mechanical properties of the Mg alloys processed by ECAP and CEC are discussed, with the emphasis on the effects of grain size and texture on the yield strength

The Principle of ECAP and CEC

Microstructures of ECAP and CEC Processed Mg Alloys

Yield Strength of the ECAP and CEC Processed Mg Alloys

Conflict of Interests

Summary and Conclusions