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 hardness layer of the shot-peening samples. Fatigue tests of the aluminum alloy with different surface conditions 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 behavior of the aluminum alloy was investigated. The results show that the effect of shot-peening on fatigue behavior of the material depends on the applied cyclic compressive stress level. Shot-peening improves fatigue life of the material when the compressive stress (sum of applied compressive stress and 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.
 CREE A M, WEIDMANN G W, HERMANN R. Film-assisted fatigue crack propagation in anodized aluminium alloys[J]. J Mat Sci Lett,1995,14(21):1505-1507.
 CREE A M, WEIDMANN G W. Effect of anodized coatings on fatigue cracks rates of aluminium alloy[J]. Surface Engineering, 1997,13(1):51-55.
 文磊,王亚明,周玉,等. LY12铝合金微弧氧化涂层组织结构对基体疲劳性能的影响[J].稀有金属材料与工程,2009,38(增刊2):747-750.WEN L, WANG Y M, ZHOU Y, et al. Influence of coating microstructure on fatigue performance of microarc oxidation coated LY12 alloy specimen[J]. Rare Metal Material and Engineering,2009,38(S2):747-750.
 RODOPOILOS C A, ROMERO J S, CURTIS S A, et al. Effect of controlled shot peening and laser shock peening on the fatigue performance of 2024-T351 aluminum alloy[J].ASM Inernational,2003,12(4):414-419.
 HONDA T, RAMULU M, KOBAYASHI A S. Effect of shot peening on fatigue crack growth in 7075-T7351[J]. J ASTM Int, 2005,2(6):39-52.
 MAJZOOBI G H, NEMATI J, NOVIN R A J, et al. Modification of fretting fatigue behavior of AL7075-T6 alloy by the application of titanium coating using IBED technique and shot peening[J]. Tribology International,2009,42(1):121-129.
 胡永会,吴运新,陈磊. 喷丸处理7075铝合金循环载荷下表面残余应力的松弛规律[J].材料研究与应用,2010,(3):174-179.HU Y H, WU Y X, CNEN L. Residual stress relaxation of shot peened 7075 aluminum alloy under cyclic load[J]. Materials Research and Application,2010,(3):174-179.
 王欣,王强,宋颖刚,等. 陶瓷喷丸对2124铝合金疲劳性能的影响[J].材料保护,2011,44(9):9-11.WANG X, WANG Q, SONG Y G, et al. Effect of ceramic shot-peening on fatigue behavior of aluminum alloy[J]. Materials Protection,2011,44(9):9-11.
 周建忠,王呈栋,黄舒,等. 6061-T6铝合金紧凑拉伸试样激光喷丸强化后的疲劳裂纹扩展性能研究[J].中国激光,2011,38(7):146-151.ZHOU J Z, WANG C D, HUANG S, et al. Study on fatigue crack growth performance of 6061-T6 aluminum alloy after laser shot peening[J]. Chinese Journal of Laser,2011,38(7):146-151.
 GAO Y K, WU X R. Experimental investigation and fatigue life prediction for 7475-T7351 aluminum alloy with and without shot peening induced residual stresses[J]. Acta Materialia, 2011,59(9):3737-3747.
 GAO Y K. Improvement of fatigue property in 7050-T7451 aluminum alloy by laser peening and shot peening[J]. Materials Science and Engineering:A,2011,528(10-11):3823-3828.
 ZUPANCA U, GRUM J. Surface integrity of shot peened aluminum alloy 7075-T651[J]. Journal of Mechanical Engineering,2011,57(5):379-384