Effect of Rolling Temperature on the Microstructure and Mechanical Properties of Mg-2Zn-0.4Y Alloy Subjected to Large Strain Rolling

Tong Wang,Qichi Le,Zhiqiang Zhang,Xiong Zhou,Yafang Li

doi:10.3390/met8110937

Abstract

Large strain rolling (LSR) has been conducted on the Mg-2Zn-0.4Y alloy. After the 1st rolling process at 250, 300, 350, and 400 °C, the alloy demonstrates a fully recrystallized microstructure. The grain size increases from 6, 8, 12, to 17 μm with an increasing rolling temperature. After the 2nd rolling process at 300 °C, twinning and shear bands were introduced. During the 3rd rolling process at 350 °C, dynamic recrystallization (DRX) was observed and resulted in a more uniform microstructure. DRX occurred because of temperature increase and large dislocation density induced by LSR. For the room temperature tensile tests, the plates rolled at 300 and 350 °C in the 1st rolling process demonstrate higher strength and lower elongation due to twinning. The one rolled at 400 °C in the 1st rolling process, shows the most uniform rolling microstructure and the best combination of strength and elongation at room temperature.

Highlights

Rare earth (RE) elements are widely used to improve the mechanical properties of Mg alloys [1,2,3,4,5].Yttrium is one of the most interesting elements, because it was found able to improve the mechanical properties and the corrosion resistance of Mg alloys at the same time [6]
The fracture of plate D is composed of large and deep dimples indicating the occurrence of large and uniform deformation prior to fracture because of the homogenous microstructural characteristics. Among these four plates, Plate A, which was rolled at 400 ◦ C in the 1st rolling process, shows the most uniform final rolling microstructure and the best combination of strength and elongation at room temperature
After the 2nd process of rolling at 300 ◦ C, deformation twins can be observed in all four plates

Summary

Introduction

Rare earth (RE) elements are widely used to improve the mechanical properties of Mg alloys [1,2,3,4,5]. Interfacial microstructure and mechanical properties of TC4/Ti3 SiC2 joints brazed at different temperatures were investigated by Wang et al [13]. In the previous studies [17,18,19,20,21], the microstructure of AZ31, AZ61 and AM60 Mg alloys were significantly refined through LSR. It is meaningful to study the microstructure evolution during the LSR of Mg-Zn-Y alloys to establish the relationship between the rolling temperature and the final strength and ductility. The Mg-2Zn-0.4Y alloy was subjected to three processes of hot rolling. 1st rolling process, six passes (two large strain passes) were conducted at temperatures of 250, 300, 350, and 400 ◦ C. The microstructure evolution after each rolling process was investigated. The room temperature tensile properties and fractures of the rolled plates were studied after all three rolling processes

Experimental Procedures

Results and Discussion

Conclusions