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Influence Of Residual Stress Field And Surface Integrity On Fatigue Properties Of TC11 Titanium Alloy And Superalloy

Posted on:2016-05-20Degree:MasterType:Thesis
Country:ChinaCandidate:Z YanFull Text:PDF
GTID:2191330479455524Subject:Materials engineering
Abstract/Summary:PDF Full Text Request
TC11 titanium alloy and FGH4097 alloy are commonly used in structural materials of aviation engine. These two alloys can easily lead to fatigue failure affected by the environment, thus, it is great significance that improving the fatigue performance of the alloys. In this paper, we investigate the fatigue properties by residual compressive stress field and the surface integrity around the shot peening.Firstly, we study the two materials’ surface integrities before and after shot peening. We comparative study three different surface integrities of the FGH4097 superalloy in UN peened, Da Qi pill shot peening, Bei Gang shot peening. In the experiment, the surface morphology of the surface was observed by SEM, and the surface marks were covered by the shot peening. The roughness of the surface was found after the roughness meter was used, and the surface roughness of the shot increased, and the effect of the Da Qi pills was more obvious. The hardness gradient layer formed after shot peening of FGH4097 high temperature alloy was not influenced by the type of projectile. The grain size of the surface grains after the shot peening was significantly more obvious. In the study of surface integrity of TC11 titanium alloy before and after shot peening, the same law was also appeared.Secondly, the residual stress fields of two materials before and after shot peening are tested. The FGH4097 was observed a residual compressive stress field of a certain depth after shot peening. The trend of residual stress field from high to low of Beigang blasting, the Di Qi pill is hook type distribution. And the use of "Hertz" contact theory is briefly explored. Then, the fatigue properties of FGH4097 high temperature alloy after Di Qi shot peening were improved by the combination of surface integrity prediction.At last, we fit the four S-N curves of r=-1 and r=0.1 after the fatigue test.The results show that the r=-1 of tensile-compression fatigue performance was improved significantly, and the fatigue strength limit was around 37.5%. The tensile fatigue properties of r=0.1 were not affected by shot peening. The fatigue failure of TC11 was observed, and the fatigue depth of the fatigue source was deeper. The effect of cyclic softening on the non-shot peening specimen is obvious.In summary, TC11 titanium alloy tension compression fatigue properties improved significantly after the introduction of shot peening residual stress field and improved the surface integrity.
Keywords/Search Tags:Shot peening, Residual compressive stress field, Surface integrity, TC11Titanium Alloy, FGH4097 superalloy, S-N curve, High cycle fatigue
PDF Full Text Request
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