(西安建筑科技大學(xué) 冶金工程學(xué)院，西安 710055)
摘 要: 采用芯棒直接擠壓對(duì)7050和2A97鋁合金斜耳片進(jìn)行孔擠壓強(qiáng)化，對(duì)比分析了其在孔擠壓前后的疲勞性能，并通過OM、SEM、XRD、TEM及Abaqus軟件，研究了兩種合金的微觀組織、疲勞斷口形貌及殘余應(yīng)力分布。結(jié)果表明：孔擠壓強(qiáng)化可有效提高兩種合金斜耳片的疲勞性能，尤其對(duì)2A97斜耳片的提高效果更加顯著，其疲勞循環(huán)周次提高幅度可達(dá)71.87%。耳片疲勞壽命得以提高的原因是經(jīng)孔擠壓后，兩種耳片孔周圍疲勞源的位置由孔內(nèi)壁表面轉(zhuǎn)移至孔內(nèi)壁近表面處，疲勞源的數(shù)量也明顯減少，并且在孔周圍形成了位錯(cuò)胞狀結(jié)構(gòu)和殘余壓應(yīng)力。2A97合金孔擠壓強(qiáng)化效果較好主要是因?yàn)榭讛D壓后產(chǎn)生了較多處的細(xì)小位錯(cuò)環(huán)和較大的殘余應(yīng)力，使得其疲勞裂紋萌生和擴(kuò)展速率的降低幅度較大而產(chǎn)生的。
關(guān)鍵字: 7050鋁合金；2A97鋁合金；斜耳片；孔擠壓；疲勞性能
（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
