摘要
The influence of free-end torsion on compressive behavior of an extruded AZ31 rod at various temperatures was studied.Pre-torsion generates a high density of dislocations and a large number of{1012}twins in the matrix,which can largely enhance the compressive yield strength at RT and 100℃.However,with increasing temperature,hardening effect via pre-torsion gradually decreases.When the compressive temperature reaches 300℃,pre-torsion reduces the compressive yield strength.Moreover,initial dislocations and twins via torsion help to refine the sub-structure and accelerate the continuous dynamic recrystallization during compression at 200℃.Thus,twisted sample exhibits more rapid flow softening behavior than the as-extruded sample at 200℃.When compressed at 300℃,the twins and dislocations via torsion were largely eliminated during the holding time,and the discontinuous dynamic recrystallization was enhanced.It is found that the compression curves of twisted sample and as-extruded sample tended to be coincident at 300℃.Related mechanisms were discussed in detail.
研究自由端扭转对AZ31挤压棒不同温度下压缩行为的影响。预扭转会在基体中产生高密度位错和大量的{1012}孪晶,从而大大提升室温和100℃的压缩屈服强度。然而,随着温度的升高,预扭转产生的硬化效果逐渐减弱。当压缩温度达到300℃时,预扭转降低了压缩屈服强度。此外,扭转产生的初始位错和孪晶有助于细化亚结构,加快200℃压缩过程中的连续动态再结晶。因此,在200℃下,扭转试样比挤压试样表现出更快的流变软化行为。当在300℃时压缩,扭转引入的孪晶和位错在保温时间内基本被消除,不连续动态再结晶得到增强。结果表明,在300℃时,扭转试样和挤压试样的压缩曲线趋于一致。对相关机制进行了详细讨论。
基金
the National Natural Science Foundation of China(No.51601154)
Southwest University Undergraduate Innovation Project(No.zsm2021026).
作者简介
Corresponding author:Bo SONG,Tel:+86-23-68253204,E-mail:bosong@swu.edu.cn。
