不同加载应力下6061-T6铝合金挤压型材的疲劳断口研究
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摘要
对6061-T6铝合金挤压型材进行了轴向拉伸疲劳试验,在加载应力121～198 MPa下测定其S-N(应力-循环次数)曲线,并对高应力(198 MPa)和低应力(130 MPa)下铝合金疲劳断口形貌特征进行分析。结果表明:6061-T6铝合金挤压型材疲劳寿命随加载应力增大而减小,其条件疲劳极限为127 MPa。随着加载应力增大,疲劳裂纹萌生呈现多源性,疲劳裂纹扩展区面积减小,裂纹扩展第一阶段的裂纹偏转更加剧烈,疲劳条带宽度增加。
The axial tensile fatigue test of 6061-T6 aluminum alloy extrudsion profile was carried out. The S-N(stress-cycletimes) curve was measured under the loading stress of 121-198 MPa, and the fatigue fracture morphologies of the aluminum alloy under high stress(198 MPa) and low stress(130 MPa) was analyzed. The results show that the fatigue life of the extrusion profile decreases with the increase of the loading stress, and the conditional fatigue limit is 127 MPa. With the increase of the loading stress, the fatigue crack initiation shows multi-source, the area of fatigue crack growth area decreases,the crack deflection in the first stage of crack growth is more intense, and the width of fatigue strip increases.
The axial tensile fatigue test of 6061-T6 aluminum alloy extrudsion profile was carried out. The S-N(stress-cycletimes) curve was measured under the loading stress of 121-198 MPa, and the fatigue fracture morphologies of the aluminum alloy under high stress(198 MPa) and low stress(130 MPa) was analyzed. The results show that the fatigue life of the extrusion profile decreases with the increase of the loading stress, and the conditional fatigue limit is 127 MPa. With the increase of the loading stress, the fatigue crack initiation shows multi-source, the area of fatigue crack growth area decreases,the crack deflection in the first stage of crack growth is more intense, and the width of fatigue strip increases.
引文
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[2]阳文辉,张月异.汽车车身6061铝合金热压缩微观结构的仿真分析[J].热加工工艺,2013,42(17):86-88.
[3]万银辉,王冠,刘志文,等.6061铝合金汽车保险杠横梁的碰撞性能[J].机械工程材料,2012(7):67-71.
[4]卢利平,罗道宝.复合锻造提高6061铝合金汽车转向节耐磨和耐蚀性能[J].轻合金加工技术,2017(11):41-44.
[5]Yahr G T.Fatigue design curves for 6061-T6 aluminum[J]Journal of Prssure Vessel Technology,1993,119(2):211-215.
[6]Jogi B F,Brahmankar P K,Nanda V S,et al.Some studies on fatigue crack growth rate of aluminum alloy 6061[J].Journal of Materials Processing Tech,2008,201(1):380-384.
[7]Takahashi Y,Shikama T,Yoshihara S,et al.Study on dominant mechanism of high-cycle fatigue life in 6061-T6aluminum alloy through microanalyses of microstructurally small cracks[J].Acta Materialia,2012,60(6/7):2554-2567.
[8]Newman Jr J C,Ruschau J J.The stress-level effect on fatigue-crack growth under constant-amplitude loading[J].International Journal of Fatigue,2007,29(9):1608-1615.
[9]汪莹,姜锋,路丽英.2219铝合金在不同加载应力下的疲劳断裂机制[J].轻合金加工技术,2016,44(9):26-31.
[10]Monsalve A,Páez M,Toledano M,et al.S-N-P curves in7075 T7351 and 2024 T3 aluminum alloys subjected to surface treatments[J].Fatigue&Fracture of Engineering Materials&Structures,2010,30(8):748-758.
[11]郑子樵,陈圆圆,钟利萍,等.2524-T34合金疲劳裂纹的萌生和扩展行为[J].中国有色金属学报,2010,20(1):37-42.
[12]Forsyth P J E.A two stage process of fatigue crack growth[C]//Proceedings of Crack Propagation Symposium.Cranfield:The College of Aeronautics,1961:76-94.
[13]Shastry C R,Levy M,Joshi A.The effect of solution treatment temperature on stress corrosion susceptibility of 7075aluminum alloy[J].Corrosion Science,1981,21(9):673-688.
[14]雷家峰,刘羽寅,杨锐,等.一种亚稳β钛合金中疲劳短裂纹穿晶扩展晶体学特征的EBSD研究[J].金属学报,2002,38(s1):272-276.
[15]倪向贵,李新亮,王秀喜.疲劳裂纹扩展规律Paris公式的一般修正及应用[J].压力容器,2006,23(12):18-15.