Effect Of Shot Peening And Anodizing Composite Process On Fatigue Life Of Materials

In this paper,7150 aluminium alloy for aviation is selected to study the process and parameters for improving its fatigue life.The purpose of this research is to study the fatigue life of materials by shot peening and anodic oxidation.The fatigue life of dry shot peening,wet shot peening and laser shot peening specimens and the surface integrity of wet shot peening specimens were tested by optical microscopy,hardness tester,scanning electron microscopy,residual stress tester,fatigue tester and anodic oxidation equipment,.After dry shot peening,wet shot peening and laser shot peening,the fatigue life of 7150 aluminium alloy was analyzed and the wet shot peening process was selected.The wet shot peening process was selected to optimize the parameters.The shot peening strengths were 0.134 mmN,0.256 mmN and 0.354 mmN.The fatigue life of wet shot peening specimens with 0.134 mmN was the highest.It is found that the maximum residual compressive stress value is 405 Mpa,the surface roughness increases with the increase of shot peening strength,and the microhardness increases with the increase of shot peening strength,in which the maximum hardness increases by 16.7% at the top layer.After shot peening,the surface microstructure of the material has been refined to a certain extent.By analyzing the fatigue fracture surface of the sample,it is found that the fatigue crack source of the raw material is on the surface of the sample.After shot peening,the fatigue crack source of the material was formation at the interior of the material.When the shot peening strength is 0.134 mmN,the maximum distance between the fatigue crack source and the surface is about 500 um.The fatigue life of the raw material samples was analyzed by anodic oxidation experiment.It was found that the fatigue life of the material was the highest when the oxidation solution was boric sulfuric acid with additive.The wet shot peening strength of 0.134 mmN was selected for anodizing.The fatigue life of it was found reduced about 47% than that of wet shot peening.