回归再时效对超高强铝合金力学性能及组织的影响  

Effect of RRA treatment on the mechanical properties and microstructure of ultrahigh strength aluminum alloys

作　　者：杨荣先 刘志义[1] 陈来[1] 鲁璐青[1] 曾苏民[1] 

机构地区：[1]中南大学材料科学与工程学院,长沙410083

出　　处：《粉末冶金材料科学与工程》2016年第2期264-269,共6页Materials Science and Engineering of Powder Metallurgy

基　　金：国家自然科学基金资助项目(51171209)

摘　　要：在传统的回归再时效(retrogression and re-aging,RRA)工艺(峰时效)基础上降低预时效或再时效温度,对Fe和Si杂质含量高的超高强Al-Zn-Mg-Cu合金挤压棒材进行RRA处理,通过拉伸性能和疲劳性能测试以及扫描电镜和透射电镜观察,研究RRA工艺对合金力学性能与组织的影响。结果表明:降低预时效或再时效温度都可明显提高该合金的塑性和抗疲劳损伤性能,略微降低合金的抗拉强度。采用峰时效温度(120℃)RRA处理后的合金,晶内的主要析出相为尺寸较大的η′相,不能被位错切割,合金强度较高(674 MPa),但塑性和抗疲劳损伤性能差,伸长率为11.1%,最终应力强度因子幅值ΔK=26.8 MPa·m1/2;降低时效温度可增加析出相中GP区粒子的比例,减小η′相的尺寸,从而提高塑性变形能力以及抗疲劳损伤性能。Based on the traditional retrogression and re-aging（RRA） technology, RRA treatment by decreasing pre-aging and re-aging temperature was performed on ultrahigh strength aluminum alloy extruded bar with high content of Fe and Si elements. The effect of RRA treatment on the mechanical properties and microstructure of ultrahigh strength aluminum alloys were investigated by tensile and fatigue tests, scanning electron microscopy（SEM） and transmission electron microscopy（TEM）. The results show that with decreasing of the pre-aging and re-aging temperatures, the ductility and the fatigue damage resistance increase obviously, and the strength decreases slightly. The large sized η′ phase is the dominant precipitate within the grains after the alloys were treated under RRA with T6 temperature（120 ℃）. The large η′ phase cannot be cut by the dislocations, so the strength of alloys is relatively higher（674 MPa）, however, the ductility（11.1%） and fatigue damage resistance decrease（ΔK=26.8 MPa·m1/2）. With decreasing of the aging temperature, the particle proportion of GP zones increases and the size of η′ phase decreases. Then, the ductility and the fatigue damage resistance are improved.

关 键 词：回归再时效 可切割粒子 超高强铝合金 挤压棒材 拉伸性能 抗疲劳损伤性能 

分 类 号：TG146.2[一般工业技术—材料科学与工程]