在Gleeble-1500热模拟试验机上进行多组热压缩试验,得到7075铝合金在成形温度573~723K,应变速率0.01~10s-1下的真应力-应变数据,用此数据作为计算应变速率敏感指数(m值)、功率耗散因子(η值)、失稳判据(ξ(ε.)值)三重判据的基本模型。通过三重判据构建包含应变在内的7075铝合金热加工图,并观察试样变形后的微观组织来验证热加工图,最终判断该合金在试验范围内的最佳变形参数。结果表明7075铝合金热加工的安全区集中在高温低应变速率区,并随着应变的增加,η值逐渐增加;通过金相观察,稳定变形区,材料由于变形发生动态再结晶而使晶粒细化;不稳定变形区,裂纹伴随着流动位错带的产生而被发现,因此可以通过包含应变的热加工图所确定的最佳工艺参数来保证无缺陷的7075铝合金锻件。
The hot deformation behaviors of 7075 aluminum alloy at the temperature range of 573-723K and strain rate range of 0.01-10s-1 have been studied by using hot compressing testing on a Gleeble-1500 simulation,then the true stress-strain data collected resulted the performance of calculations for strain rate sensitivity(m-value),power dissipation efficiency(η-value) and instability parameter(ξ-value) under the different ture strain.The processing maps including strain of hot deformation of 7075 aluminum alloy was constructed according to three criterion of the above,and the microstructures of deformed specimens were observed as a evidence index.The regions of flow instabilities and optimum hot working condition are can be attained from the processing map and microstructure.The results show that the security domain mainly of hot working for 7075 aluminum alloy in the high temperature and low strain rate region,furthermore the power dissipation factor increase gradually with increasing strain;by the metallographic observations,the grain refinement by dynamic recrystallization under the stable deformation conditions,and bands of flow localization which have been associated with cracking under the unstable deformation conditions.The optimal working parameters identified by the processing maps including strain contribute to designing the hot forming process of 7075 aluminum alloy forging without any defect.
参考文献
[1] | 杨立斌,张辉,彭大暑,段炼.7075铝合金高温流变行为的研究[J].热加工工艺,2002(01):1-2,5. |
[2] | 黄光胜,汪凌云,陈华,黄光杰,张所全.2618铝合金的热变形和加工图[J].中国有色金属学报,2005(05):763-767. |
[3] | 鲁世强,李鑫,王克鲁,董显娟,李臻熙,曹春晓.基于动态材料模型的材料热加工工艺优化方法[J].中国有色金属学报,2007(06):890-896. |
[4] | 李成侣,潘清林,刘晓艳,何运斌,李文斌.2124铝合金的热压缩变形和加工图[J].材料工程,2010(04):10-14. |
[5] | Prasad YVRK;Rao KP .Processing maps and rate controlling mechanisms of hot deformation of electrolytic tough pitch copper in the temperature range 300-950 degrees C[J].Materials Science & Engineering, A. Structural Materials: Properties, Misrostructure and Processing,2005(1/2):141-150. |
[6] | 汪凌云,范永革,黄光杰,黄光胜.镁合金AZ31B的高温塑性变形及加工图[J].中国有色金属学报,2004(07):1068-1072. |
[7] | 刘娟,崔振山,李从心.包含应变的三维加工图与有限元相结合的金属可加工性分析[J].机械工程学报,2008(05):108-113. |
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