温度对多次变形铝合金力学性能及微观组织的影响

Effect of Temperature on Microstructure and Mechanical Properties of Aluminum Alloy

采用拉伸试验、硬度测试、金相分析等方法测试和分析了7XXX铝合金经过热挤压、T6热处理后的强度、硬度和金相组织。研究了在不同温度下,变形次数(1～4次)对7XXX铝合金组织与性能的影响。研究表明:320℃时,7XXX铝合金晶粒的尺寸随变形次数的增加而变大,合金的硬度、强度随变形次数的增加而降低。这主要是因为变形而产生的形变内应力得到一定程度的释放,晶粒形核所需要的驱动力减少;480℃时,随着变形次数的增加,其硬度、强度增加。这主要是因为保温一定时间使得合金变软,不易发生动态再结晶。

After hot extrusion and heat treatment,the tensile test,hardness test and metallographic analysis were used to investigate the mechanical properties and microstructure of 7XXX aluminum alloy under different deforming times.The effects of deforming degree（1～4 times） on microstructure and mechanical properties of 7XXX aluminum alloy at different temperature were studied.The results indicate that,at 320 ℃,the grain size largens and the hardness and strength of the alloy decrease with the increase of deforming degree.Because stress releases to some extent in deformation,the driving-force of grain nucleation decreases.At 480 ℃,the hardness,strength and the angle between the elongated direction of fibroustissue and squeezing direction increase gradually with the increase of deforming degree.The reason is that the dynamic recrystallization becomes difficult when alloy softens in thermal insulation.