Improved Edge Quality for AZ31 Sheets Using Online Heating Rolling Technique
- PDF / 3,874,406 Bytes
- 10 Pages / 593.972 x 792 pts Page_size
- 83 Downloads / 145 Views
ASM International 1059-9495/$19.00
Improved Edge Quality for AZ31 Sheets Using Online Heating Rolling Technique Qiang Liu, Jiangfeng Song, Hua Zhao, Biquan Xiao, Xiaojian Zheng, and Fusheng Pan (Submitted December 16, 2019; in revised form April 28, 2020; published online July 13, 2020) The edge quality of AZ31 sheets prepared by online heating rolling (O-LHR) technique under different rolling temperatures has been investigated. The AZ31 sheets are rolled from 3 mm to around 1 mm via four passes under three different temperatures. Each pass reduction keeps a constant about 25%. For comparison, a series of sheets are also rolled by conventional rolling (CR) under the same condition. The macroscopic observation for sheets rolled by both processes and microstructure examination for the rolled sheets via O-LHR are performed to characterize the edge cracking behavior. The results reveal that the edge quality of sheets after O-LHR is better than that through CR and remarkably improves with the increase in temperature. No obvious edge crack appears in AZ31 sheet rolled by O-LHR at a rolling temperature of 250 °C. This can be attributed to the enhanced dynamic recrystallization and the activation of non-basal slip, which results in a homogeneous microstructure at the edge. Keywords
AZ31 alloy sheet, dynamic recrystallization, edge crack, non-basal slip, online heating rolling (O-LHR)
1. Introduction Magnesium alloys, as the lightest structural metallic materials, have drawn much attention over recent decades owing to its high specific strength, favorable heat dissipation and damping properties and thus are widely applied to the vehicle industry and electronic products. The increased requirements of lightweighting and saving energy can further promote the massive application for magnesium alloys (Ref 1-6). However, it is acknowledged that magnesium alloy has poor formability due to its close-packed hexagonal crystal structure, leading to the activation of limited slip systems at room temperature (Ref 7-9). Therefore, it is easy to produce lots of edge cracks on magnesium alloy sheet when subjected to rolling at low temperature, which causes the poor quality and high cost (Ref 10, 11). Edge crack is a common defect in the case of rolling for magnesium alloys sheet. In order to carry out the subsequent rolling process successfully, the edge with large cracks in the rolled sheets has to be cut off and in turn reduces the yield. Massive efforts have been made by researchers to study the edge crack in Mg sheet over the past years. Zhang et al. (Ref 12) predicted the edge crack of AZ31 sheet during rolling by thermal-mechanical-damage coupled finite elements model. They found that the rolling force and the plastic damage of the
Qiang Liu, Jiangfeng Song, Hua Zhao, Biquan Xiao, Xiaojian Zheng, and Fusheng Pan, National Engineering Research Center for Magnesium Alloy, Chongqing University, Chongqing 400045, China. Contact e-mail: [email protected].
4212—Volume 29(7) July 2020
edge increased with the increase in reducti
Data Loading...
