摘要
通过金相观察和电子背散射衍射技术,研究了7A85铝合金在应变速率0.001~1 s^(−1)、变形温度250~450°C条件下的微观组织演变规律,并基于K-M位错密度模型,建立了7A85铝合金“两阶段”式K-M位错密度模型。结果表明,在7A85铝合金热变形过程中,动态回复和动态再结晶是微观组织演变的主要机制;350~400°C是动态回复向动态再结晶的转变温度区间。在低温条件(≤350°C)下主要发生动态回复,高温条件(≥400°C)主要发生动态再结晶;此时,微观组织演变对于温度的敏感性较高,且随着温度的升高,平均取向差角(θˉ_(c))显著增加,增加范围在0.93°~7.13°之间,同时微观组织中f_(LAGBs)明显减少,最高下降幅度达24%。
The microstructure evolution of 7A85 aluminum alloy at the conditions of strain rate(0.001−1 s^(−1))and deformation temperature(250−450°C)was studied by optical microscopy(OM)and electron back scattering diffraction(EBSD).Based on the K-M dislocation density model,a two-stage K-M dislocation density model of 7A85 aluminum alloy was established.The results reveal that dynamic recovery(DRV)and dynamic recrystallization(DRX)are the main mechanisms of microstructure evolution during thermal deformation of 7A85 aluminum alloy.350−400°C is the transformation zone from dynamic recovery to dynamic recrystallization.At low temperature(≤350°C),DRV is the main mechanism,while DRX mostly occurs at high temperature(≥400°C).At this point,the sensitivity of microstructure evolution to temperature is relatively high.As the temperature increased,the average misorientation angle(θˉ_(c))increased significantly,ranging from 0.93°to 7.13°.Meanwhile,the f_(LAGBs) decreased with the highest decrease of 24%.
作者
胡建良
吴秀江
薄宏
焦子腾
黄始全
金淼
HU Jian-liang;WU Xiu-jiang;BO Hong;JIAO Zi-teng;HUANG Shi-quan;JIN Miao(College of Mechanical Engineering,Yanshan University,Qinhuangdao 066004,China;State Key Laboratory of Metastable Materials Science and Technology,Yanshan University,Qinhuangdao 066004,China;State Key Laboratory of High Perfermance Complex Manufacturing,Central South University,Changsha 410083,China)
基金
Project(51675465)supported by the National Natural Science Foundation of China
Project(E2019203075)supported by the Natural Science Foundation of Hebei Province,China
Project(BJ2019001)supported by the Top Young Talents Project of the Education Department of Hebei Province,China
Project(Kfkt2017-07)supported by the State Key Laboratory Program of High Performance Complex Manufacturing,China。
关键词
热变形
微观组织演变
动态再结晶
位错密度模型
hot deformation
microstructure evolution
dynamic recrystallization
dislocation density model