Study On Surface Properties Of TC4 Titanium Alloy By Mechanical Punching And Annealing

TC4 alloy is widely used in aerospace,marine,sports equipment and biomedical fields due to its excellent comprehensive performance.When implanted into the human body as a biomedical material,with the extension of service time,wear and corrosion will inevitably occur.At the same time,TC4 will release toxic ions containing Al and V,reduce cell adaptability,and cause harm to the human body.The surface nanocrystallization of materials is an effective way to improve the wear resistance and corrosion resistance,and to suppress the precipitation of toxic ions.To this end,a mechanical punching and annealing method is proposed in order to achieve the purpose of nanocrystallization of the TC4 titanium alloy to enhance the performance.The main work content is:(1)Research on microstructure and hardness performance.Firstly,through analysis of X-ray diffraction pattern,use Scherere-Wilson formula to calculate the surface grain size of samples with different punching time.The results show that Within the range,with the increase of the punching time,the grain size of the surface layer of the sample is continuously reduced,and the thickness of the plastic deformation layer is continuously increased.Subsequently,the 45-minute punched sample is annealed.The experimental results show that with the annealing With increasing temperature,the grain size of the surface layer of the sample first decreases and then increases;The grain size after punching at 45 min + 650 ? annealing is the smallest.The hardness of the sample was also tested using a micro hardness tester.The test result was that the surface hardness of the TC4 alloy was mechanically punched.The surface hardness of the sample was significantly increased.The increase in the temperature decreases first and then increases,and the relationship between the hardness and the grain size of the mechanically punched sample basically conforms to the Hall-Petch formula.(2)Research on surface abrasion resistance.First,the friction and frictionbehavior of the treated TC4 alloy sample was tested by a CMT-I friction tester.The results show that with the increase of normal load and wear time,the wear of the alloy Also gradually increased.A subsequent comparison test with the untreated alloy sample revealed that the wear resistance of the treated alloy sample was greatly improved,and the wear resistance of the TC4 sample punching at 45min+ 650 ?annealing was the best.The abrasion resistance was improved by 1.467 times compared to the original sample.(3)Research on surface corrosion resistance.First using the electrochemical workstation PARSAT 4000 to conduct experiments.After analyzing the polarization curve to obtain mechanical punching treatment,the corrosion current density of TC4 alloy decreased sharply,indicating that its corrosion resistance was significantly enhanced.Subsequently,the samples punched at 45 min different annealing temperatures were tested separately.It was found that the corrosion resistance of the annealed samples was further improved,and the corrosion potential of the samples after annealing by punching for 45min+650°C annealing was relatively Since the original sample moved 180.72 mV in the forward direction,the corrosion current density decreased by 175.59 nA,which is the best value among all samples,which proves that the sample has the best corrosion resistance after annealing by punching for45 min + 650 ?.The research results in this paper provide new processing methods and theoretical support for the improvement of TC4 titanium alloy medical performance.