摘要
目的通过塑性成形工艺实现镁锂合金构件的高性能成形制造。方法采用热压缩试验研究了铸态LAZ931镁锂合金不同温度与不同应变速率下的热变形行为,通过多向锻造技术制备镁锂合金锻坯,并通过等温超塑挤压成形。结果铸态镁锂合金具有较好的热变形性能,它在低温高应变速率下易失稳,热加工失稳区随变形量的增加逐渐增大;多向锻造可通过动态再结晶显著细化其两相微观组织,使合金获得良好的超塑性变形能力,在300℃和应变速率5×10^(–4) s^(–1)条件下,锻态合金的延伸率和流变抗力分别达到200%以上和8 MPa左右;通过超塑性挤压成形实现了筒体构件的成形,成形后力学室温屈服强度、抗拉强度及延伸率分别达到了163 MPa、197 MPa和22%左右,相比于铸态合金,分别提高了20.7%、19.4%和83%。结论通过热压缩变形研究了镁锂合金的热变形行为,其流变应力随温度的升高而降低,随应变速率的增加而增加,表现出正的应变速率敏感性;通过超塑性等温挤压可制备出具有良好综合性能的镁锂合金筒体结构。
The work aims to realize the high-performance forming of magnesium-lithium alloy components through plastic forming processes.The hot deformation behavior of as-cast LAZ931 magnesium-lithium alloys at various temperatures and strain rates was investigated via hot compression tests.Magnesium-lithium alloy forgings were fabricated by multi-directional forging technology and formed through isothermal superplastic extrusion.The as-cast magnesium-lithium alloy demonstrated excellent hot deformation performance,but it was prone to instability at low temperatures and high strain rates,and the zone of hot processing instability gradually expanded with the increase in deformation.Multi-directional forging could significantly re-fine the two-phase microstructure through dynamic recrystallization,allowing the alloy to acquire good superplastic deformation ability.The elongation and flow resistance of the forged alloy at 300℃and a strain rate of 5×10^(–4) s^(–1) reached over 200%and approximately 8 MPa,respectively.The forming of cylinder components was accomplished through superplastic extrusion forming.After forming,the mechanical room temperature yield strength,tensile strength,and elongation reached approximately 163 MPa,197 MPa,and 22%,respectively,which increased by 20.7%,19.4%,and 83%,respectively,compared to those of the as-cast alloy.The hot deformation behavior of magnesium-lithium alloys is investigated through hot compression deformation.Its flow stress decreases with the rise in temperature and increases with the increase in strain rate,presenting a positive strain rate sensitivity.Cylinder structures of magnesium-lithium alloys with favorable comprehensive properties can be prepared by superplastic isothermal extrusion.
作者
吕云翔
董楹
傅文亮
高诗情
夏祥生
卢振
LYU Yunxiang;DONG Ying;FU Wenliang;GAO Shiqing;XIA Xiangsheng;LU Zhen(School of Materials,Harbin Institute of Technology,Harbin 150001,China;AVIC Harbin Aircraft Industory Group Co.,Ltd.,Harbin 150066,China;Chongqing Changan Wangjiang Industrial Group Co.,Ltd.,Chongqing 400071,China;Southwest Institute of Technology and Engineering,Chongqing 400039,China)
出处
《精密成形工程》
北大核心
2025年第8期52-59,共8页
Journal of Netshape Forming Engineering
关键词
镁锂合金
超塑成形
热加工图
微观组织形貌
magnesium-lithium alloy
superplastic forming
hot processing map
microstructure morphology
