蠕变和人工时效对2524铝合金疲劳裂纹扩展性能的影响  

Effect of creep and artificial aging on fatigue crack growth performance of 2524 aluminum alloy

作　　者：刘义伦[1,2] 王卿 刘驰 李松柏 何军[1] 赵先琼 LIU Yi-lun;WANG Qing;LIU Chi;LI Song-bai;HE Jun;ZHAO Xian-qiong(College of Mechanical and Electrical Engineering,Central South University,Changsha 410083,China;Light Alloy Research Institute,Central South University,Changsha 410083,China)

机构地区：[1]中南大学机电工程学院,长沙410083 [2]中南大学轻合金研究院,长沙410083

出　　处：《吉林大学学报（工学版）》2019年第5期1636-1643,共8页Journal of Jilin University:Engineering and Technology Edition

基　　金：国家自然科学基金项目(51375500);中南大学中央高校基本科研业务费专项资金项目(2018zzts465);湖南省科技计划项目(2016GK2005);河北省高等学校科学技术研究青年基金项目(QN2018013)

摘　　要：针对蠕变时效和人工时效对2524铝合金疲劳裂纹扩展性能的影响进行了研究,结合透射电镜下合金的微观组织演变,分析了不同时效状态下析出相对合金疲劳性能的影响规律。结果表明:时效4 h后蠕变时效和人工时效合金内微观组织都是以Cu-Mg原子团簇和GPB区为主,表现出较好的抗疲劳性能。相比时效4 h,时效9 h后合金内主要析出相为针状S′相,粗大S′相的出现改变了位错滑移方式,降低了滑移的可逆性,加速了疲劳损伤积累,因此在应力强度因子范围ΔK≤7 MPa·m1/2的近门槛区,合金抗疲劳性能明显下降。时效24 h后合金晶界处出现无沉淀析出带,晶内析出相尺寸也更大,进一步加速了合金的疲劳裂纹扩展速率。蠕变应力加速了合金的时效析出进程,相比人工时效,在相同时效时间下,蠕变时效合金内析出相尺寸更大,屈服强度和硬度提高,但抗疲劳性能下降。The effects of creep aging and artificial aging on the fatigue crack propagation properties of 2524 aluminum alloy were investigated. The influence of aging conditions on the fatigue properties of the alloy was analyzed based on the microstructure evolution of the alloy under TEM. The results show that the microstructures of artificial aging and creep aging alloys are mainly Cu-Mg clusters and GPB zones after aging for 4 h,showing good fatigue resistance. Compared with 4 h,after aging for 9 h the microstructures of the alloy are mainly acicular S′phase. The appearance of these coarse S′phases changes the slip mode of dislocation,which reduces the reversibility of slip and accelerates the accumulation of fatigue damage.Near the threshold section of ΔK ≤ 7 MPa·m1/2,the alloy fatigue resistance decreases significantly. The precipitate free zone appears at the grain boundary of the alloy after aging for 24 h,and the precipitates in the grain are also larger in size,further accelerating the fatigue crack growth rate of the alloy. Creep stress accelerates the precipitation process of alloy and compared with artificial aging,the creep aging alloy has larger precipitate size,higher yield strength and hardness,but lower fatigue resistance at the same aging time.

关 键 词：航空航天材料 疲劳裂纹扩展 断裂力学 2524铝合金 蠕变时效 析出相 

分 类 号：TG146.2[一般工业技术—材料科学与工程]