固溶处理对喷射成形7055铝合金组织及性能的影响

Effect of solution treatment on microstructure and properties of spray formed 7055 aluminum alloy

采用差示扫描量热仪(DSC)、扫描电镜(SEM)、电子背散射衍射(EBSD)技术、常温拉伸、剥落腐蚀试验等研究了固溶处理对喷射成形7055铝合金组织和性能的影响。结果表明:随着固溶温度的升高,合金中粗大第二相面积分数逐渐减小,AlZnMgCu相和Al_(2)CuMg(S)相基本回溶,只残留少量的Al_(7)Cu_(2)Fe相,亚晶尺寸和再结晶面积分数随着固溶温度的升高和固溶时间的延长而增大,导致抗拉强度先增大后减小。合金经470℃固溶处理2 h+时效处理后,抗拉强度、伸长率和剥落腐蚀性能分别为613.4 MPa、8.9%和EB+级。喷射成形7055铝合金的静态再结晶机制包括“原有晶界弓出机制”和“亚晶合并机制”。

Effect of solution treatment on microstructure and properties of spray formed 7055 aluminum alloy was studied using differential scanning calorimetry(DSC),scanning electron microscopy(SEM),electron backscatter diffraction(EBSD) technique,room temperature tensile testing and exfoliation corrosion testing.The results show that as the solution temperature increase,the area fraction of the coarse second phases in the alloy gradually decreases,and the AlZnMgCu and Al_(2)CuMg(S) phases basically dissolve into the matrix,leaving only a small amount of Al_(7)Cu_(2)Fe phase.The subgrain size and recrystallization area fraction increase with the increase of solution temperature and the increase of solution time,leading to an increase in tensile strength first and then a decrease.After solution treatment at 470 ℃ for 2 h and aging treatment,the tensile strength,elongation,and exfoliation corrosion resistance of the alloy are 613.4 MPa,8.9%,and EB+grade,respectively.The static recrystallization mechanism of the spray formed 7055 aluminum alloy includes the “original grain boundary bowing out mechanism” and the “subgrain merging mechanism”.