| As the excellent performance of low density, low elastic modulus, highspecific strength, high temperature resistance, good low temperature resistance,high corrosion resistance and good biological compatibility, titanium alloy waswidely used in important fields of aerospace, automotive ships, weapons,electronics, petrochemical, medical engineering and other military and civilfields. But, because titanium alloy has the poor anti-fatigue performance, thefurther development of titanium alloy is limited. For the problem of poor fatigueperformance of TC4titanium alloy, this paper uses the centrifugal barrelfinishing technology to improve the surface integrity of TC4titanium alloy andenhance its anti-fatigue performance.This paper analyzed the titanium alloy’s fatigue damage mechanism and itsmain influence factors firstly, and then analyzed the mechanism of centrifugalbarrel finishing on improving the titanium alloy’s anti-fatigue performance.Based on the analysis results, the experimental studies were conducted on TC4 titanium alloy using centrifugal barrel finishing technology. The main contentsand conclusions of the experimental study are as follows:1. Orthogonal experiment were applied to study the influence regular ofcentrifugal barrel finishing parameters on TC4titanium alloy’s surfaceroughness. Orthogonal experiments showed that the barrel finishing parametersordered by influence on surface roughness is diameter of grinding block, theprocessing time followed by，and then is load capacity; The good factors levelcollocation for this experiment were determined: grinding block is Φ10indiameter, load capacity of50%and processing time of50mins.2. Using finite element simulation and combined with orthogonal test, theinfluence regular of centrifugal barrel finishing parameters on residual stress ofTC4titanium alloy was studied. The regular of residual stress changing with thediameter of grinding block got by finite element simulation is almost consistentwith the experiment measured results. Orthogonal experiments showed that thebarrel finishing parameters ordered by influence on residual stress is diameter ofgrinding block, followed by loading quantity, the last is processing time. Goodfactors level collocation for this experiment are: grinding block is Φ10indiameter, load capacity of50%and processing time of40mins or50mins.3. The experimental researchs were conducted on basis of orthogonalexperiment process parameters optimization. By using microscopic hardnesstester, XRD diffraction, metallographic microscope and scanning electronmicrocscopy(SEM), the influence of centrifugal barrel finishing on the microhardness, X-ray diffraction, microstructure of TC4titanium alloy wasanalyzed. The results showed that: at the processing time of50mins，the surfacemicrohardness of titanium alloy increase89.6HV compared with the substract;The maximum microhardness appears at the surface of specimen and decreasesalong the deep layer gradually; When the deep layer is about500m, thehardness value is basically the same as the sample before processing, and itchanges no longer ever since; After centrifugal barrel finishing, the peak ofX-ray diffraction growed wider and shifted to the left compared with thesamples before finishing, the sample surface produced obvious plasticdeformation, and the plastic deformation layer had a gradient change along thedeep; The depth of the plastic deformation layer increased gradually with theextension of processing time, when the processing time is more than40mins,the depth of the plastic deformation layer changed little, but the grain size gotfurther elaboration.4. Under the condition of610MPa stress，the pull-pull fatigue test wereconducted for the fatigue sample that before centrifugal barrel finishing andafter centrifugal barrel finishing. The test results showed that the centrifugalbarrel finishing can effectively improve the pull-pull fatigue life of TC4titanium alloy.In this paper, through the simulation and experimental research, theoptimum process parameters of centrifugal barrel finishing on TC4titaniumalloy was determined, and the surface integrity of titanium alloy got comprehensive improved after finishing, which has great significance forimproving the anti-fatigue performance of titanium alloy. |
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