交变法向载荷下2024铝合金微动疲劳断口分析  

Fretting Fatigue Fracture Analysis of 2024 Aluminum Alloy under Alternating Normal Load

作　　者：张育轩 李欣 杨建伟 田帅 刘乐强 ZHANG Yuxuan;LI Xin;YANG Jianwei;TIAN Shuai;LIU Leqiang(School of Mechanical-Electrical and Vehicle Engineering,Beijing University of Civil Engineering and Architecture,Beijing 100044,China;Beijing Key Laboratory of Performance Guarantee on Urban Rail Transit Vehicles,Beijing 100044,China)

机构地区：[1]北京建筑大学机电与车辆工程学院,北京100044 [2]城市轨道交通车辆服役性能保障北京市重点试验室,北京100044

出　　处：《热加工工艺》2024年第18期79-83,89,共6页Hot Working Technology

基　　金：国家自然科学基金青年基金项目(51905028);北京市教育委员会科技计划一般项目(KM202110016002);北京建筑大学金字塔人才培养工程项目(JDYC20200323)。

摘　　要：针对机械结构中广泛存在的微动疲劳失效问题,利用可施加交变法向载荷与远端载荷的双轴加载微动疲劳试验系统,研究了在交变法向载荷作用下,局部滑移和全局滑移两种运行机制对2024铝合金疲劳断裂的影响。利用扫描电镜对疲劳断口进行微观分析。结果表明:局部滑移与全局滑移两种运行机制下裂纹均萌生在试件与微动垫接触边界,局部滑移试件是由于接触边界产生多个裂纹并不断融合扩展导致试件断裂,全局滑移试件为单一裂纹源导致的试件断裂。在裂纹扩展区可看到疲劳辉纹与2024铝合金中的加强相,铝合金中的加强相可阻碍裂纹扩展。除此以外还可清晰的看到大量解理、准解理、撕裂棱形貌;疲劳瞬断存在大量韧窝以及二次裂纹,表现出典型韧性断裂特征。Aiming at the fretting fatigue failure problem widely existing in the mechanical structures,the influence of partial slip and gross slip on the fatigue fracture of 2024 aluminum alloy under alternating normal load was studied by using a biaxial fretting fatigue test system,which can apply the alternating normal load and the distal load.The fatigue fracture was analyzed by scanning electron microscope.The results show that the cracks are initiated at the contact boundary between the specimen and the fretting pad under both partial slip and gross slip mechanisms.The fracture of the partial slip specimen is caused by multiple cracks at the contact boundary and continuous fusion and expansion,and the fracture of the gross slip specimen is caused by a single crack source.The fatigue striations and strengthening phase in 2024 aluminum alloy can be seen in the crack propagation zone,and the strengthening phase in aluminum alloy can hinder the crack propagation.In addition,a large number of cleavage,quasi cleavage and torn prisms can be clearly seen.There are a lot of dimples and secondary cracks in fatigue transient fracture,showing typical ductile fracture characteristics.

关 键 词：2024铝合金 断口分析 微动疲劳 交变法向载荷 

分 类 号：TG146.21[一般工业技术—材料科学与工程]