(西安建筑科技大学 冶金工程学院，西安 710055)
摘 要: 采用芯棒直接挤压对7050和2A97铝合金斜耳片进行孔挤压强化，对比分析了其在孔挤压前后的疲劳性能，并通过OM、SEM、XRD、TEM及Abaqus软件，研究了两种合金的微观组织、疲劳断口形貌及残余应力分布。结果表明：孔挤压强化可有效提高两种合金斜耳片的疲劳性能，尤其对2A97斜耳片的提高效果更加显著，其疲劳循环周次提高幅度可达71.87%。耳片疲劳寿命得以提高的原因是经孔挤压后，两种耳片孔周围疲劳源的位置由孔内壁表面转移至孔内壁近表面处，疲劳源的数量也明显减少，并且在孔周围形成了位错胞状结构和残余压应力。2A97合金孔挤压强化效果较好主要是因为孔挤压后产生了较多处的细小位错环和较大的残余应力，使得其疲劳裂纹萌生和扩展速率的降低幅度较大而产生的。
关键字: 7050铝合金；2A97铝合金；斜耳片；孔挤压；疲劳性能
（School of Metallurgical Engineering, Xi’an University of Architecture and Technology, Xi’an 710055, China）
Abstract:The oblique lugs of 7050 aluminum alloy were extruded and 2A97 alloy by mandrel direct extrusion were investigated, and the fatigue properties of oblique lugs of alloys before and after hole extrusion were compared and analyzed. Then, the microstructure, fatigue fracture morphology and residual stress distribution of the two alloys were investigated by OM, SEM, XRD TEM and Abaqus software. The results show that the fatigue properties of the oblique lugs can be improved effectively by the hole extrusion strengthening, especially for the 2A97 aluminum alloy oblique lugs, and its fatigue cycle are increased by 71.87%, respectively. There are two main reasons for the increase in fatigue cycles. One reason is that the variation of fatigue source position and number around the lug hole, they change from the surface of inner wall to near inner wall, and the number of the fatigue sources is decreased obviously. The other reason is that the dislocation cell structure and residual compressive stress are formed around the hole during extrusion. In addition, more smaller dislocation loops and larger residual stress are produced in the 2A97 alloy during extrusion, which makes the initiation and propagation rates of fatigue crack decrease in some degree. Therefore, the strengthening effect of hole extrusion on the 2A97 alloy is better.
Key words: 7050 aluminum alloy; 2A97 alloy; oblique lugs; hole extrusion; fatigue properties
