摘要: |
采用陶瓷弹丸对 7B50-T7751 铝合金进行不同覆盖率(100%、300%、600%、1 000%)的表面喷丸强化处理,探究了 7B50-T7751 铝合金表面粗糙度、表面微观组织以及残余应力场等表面形态因素在不同喷丸覆盖率作用下的衍化规律。通过应力比 R=0.06 的轴向加载疲劳试验,分析表面形态改变对疲劳强度的影响。结果表明,不同覆盖率的喷丸强化处理均能改善该材料的疲劳性能,其中在 100%~300%喷丸覆盖率下,疲劳强化增益效果最为明显,其机理是试件在喷丸处理后表面形态得以改善,同时表层形成较高水平的残余压应力,这两种效应的共同作用使疲劳裂纹源从材料表面缺陷处向内迁移到材料内部容易产生应力集中的夹杂处。 |
关键词: 喷丸强化 覆盖率 7B50-T7751 铝合金 表面形态 疲劳强度 |
DOI:10.11933/j.issn.1007-9289.20210422003 |
分类号:TG178;TB111 |
基金项目:国家自然科学基金资助项目(91860206) |
|
Surface Morphology Evolution Together with Its Effect on Fatigue Properties in Shot Peening of Aluminum Alloy 7B50-T7751 |
Gao Guoqiang1,2, Chen Jinxiang2, Xue Hongqian1, Zhang Xianjie1, Yang Hui2
|
1.School of Mechanical Engineering, Northwestern Polytechnical University, Xi’ an 710072 , China;2.AVIC Xi’ an Aircraft Industry Group Company LTD., Xi’ an 710089 , China
|
Abstract: |
Shot peening processing of aluminum alloy 7B50-T7751 is carried out by ceramic pellets with different coverage (100%, 300%, 600%, 1 000%). The surface morphology evolution of the shot peened alloy, which includes surface roughness, microstructure and residual stress distribution, are investigated. The fatigue strength under different shot peening conditions are then evaluated by axial fatigue test with the stress ratio of 0.06. Results show that shot peening processing can improve the alloy’ s fatigue strength for all concerned shot peening coverages, while the improvement rate is the most significant when the shot peening coverage is from 100% to 300%. Fracture morphology analysis indicates that the mechanism of fatigue failure behaves in transition of the crack initiation position, from the surface defects to the internal inclusion where the concentrated stress field is generated, due to the improvement of the surface quality and the combined influence of the compressive residual stress field. |
Key words: shot peen strengthening coverage aluminum alloy 7B50-T7751 surface morphology fatigue strength |