喷丸处理对6151-T6铝合金旋转弯曲疲劳性能的影响.pdf

喷丸处理对6151-T6铝合金旋转弯曲疲劳性能的影响
73
喷丸处理对6151-T6铝合金旋转弯曲
疲劳性能的影响
Effect of Shot-peening on Fatigue Behavior o
6151-T6 Aluminum Alloy Under Rotating Bending
张艳斌,鲁连涛,薛弼
(西南交通大学牵引动力国家重点实验室,成都610031)
ZHANG Yan-bin, IU Lian-tao, XUE Bi-yi
State Key Laboratory of Traction Power, Southwest
Jiaotong University, Chengdu 610031, China
摘要:对经过电解抛光、喷丸处理和喷丸处理冉抛光的三种6151-T6铝合金试样的表面粗糙度及喷丸处理后试样表面
硬化层的硬度进行测试。对三种表面状态不同的铝合金材料进行旋转弯曲疲劳实验。研究喷丸处理试样表面残余应力
随疲劳实验的变化情况,以及喷丸处理对该铝合金疲劳性能的影响。结果表明:喷丸处理对材料疲劳性能的影响与加载
的压应力水平有关。当加载的压应力与表面残余压应力之和不超过材料表面硬化层的循环屈服强度时,硬化层中的残
余压应力在疲劳过程中不发生应力松弛,疲劳寿命得到大幅度提高;反之,将发生应力松弛现象,疲劳寿命的提高程度受
残余压应力松弛程度的影响。此外,喷丸处理造成的材料表面粗糙度的增加,在全应力幅范围,使材料的疲劳寿命略有
降低。
关键词:铝合金;疲劳;喷丸;应力松弛
dols10.3969/j.issn.1001-4381.2014.04.013
中图分类号:O346.2文献标识码
文章编号;1001-4381(2014)04-0073-06
Abstract: The surface roughness of electro-polishing, shot-peening and polishing after shot-peening
6151-T6 aluminum alloy samples were measured together with Vickers hardness on the surface hard
mess layer of the shot-peening samples. Fatigue tests of the aluminum alloy with different surface con
ditions were performed under rotary bending loading. The residual stress on the surface for the shot-
peening specimen was measured during the fatigue test, and the effect of shot-peening on fatigue be
avior of the aluminum alloy was investigated. The results show that the effect of shot-peening on fa
tigue behavior of the material depends on the applied cyclic compressive stress level. Shot-peening im
proves fatigue life of the material when the compressive stress (sum of applied compressive stress an
residual compressive stress) on the surface layer is below the cyclic yield strength of the layer. The
great improvement of fatigue life is due to the fact that residual compressive stress induced by shot
peening cannot be released during fatigue tests. On the contrary, the residual compressive stress can
be released when the compressive stress on the surface layer exceeds the cyclic yield strength of the
layer. The improvement degree of fatigue life is affected by the extent of residual stress relaxation on
the surface. Besides, the surface roughness induced by shot-peening slightly decreases the fatigue life
of the material in the full stress amplitude range
Key words: aluminum alloy; fatigue; shot-peening; stress relaxation
铝合金的比强度高,能够满足机械结构向高强度瓷薄膜,能够提高铝合金的抗磨耗、抗腐蚀等性能。但
轻量化发展的要求。通常,为了提高铝合金抗磨耗、抗是,研究发现1-,在疲劳载荷作用下,陶瓷薄膜受基
腐蚀和抗疲劳等性能,工程上常采用阳极氧化等表面体材料塑性变形的影响容易开裂,从而形成缺口效应,
涂层处理和喷丸等表面硬化处理技术对铝合金进行表降低基体材料对疲劳的抵抗;喷丸处理使材料表面层
面改性。其中,涂层处理使铝合金表面形成坚硬的陶发生塑性変形,是一种对材料本身依赖性较少、非常方