Investigation Into The Friction And Wear Properties Of Laser Additive Manufacturing Ti-6Al-4V Alloy

Ti-6Al-4V(TC4)titanium alloys,as?/?titanium alloys with medium strength and outstanding comprehensive properties,have a great number of applications in the aerospace in dustry and military equipment industry.However,the wear resistance of titanium alloys is poor,and the surface is easy to bite and abrasion during the wearing process,which causes a large amount of economic loss.Therefore,it is extremely important to study the friction and wear properties of titanium alloys.In this paper,Ti-6Al-4V titanium alloy specimens are formed by laser selective melting technology,and the microstructure of the material is changed through different heat treatment schemes.Finally,a pin-disk friction and wear tester,Vickers hardness tester,nanoindenter,etc.are used to explore Finally,a pin-disk friction and wear tester,Vickers hardness tester,nanoindenter,etc.were used to explore the friction and wear performance of the sample,in order to find a method to improve the low wear performance of the TC4 titanium alloy.The main research results and conclusions obtained are as follows:(1)The microstructure of the as-built sample is mainly acicular martensite with a uniform width of 0.75?m,and the grain size and orientation are highly uneven.After solution treatment,acicular?'martensite was transformed into a spherical and plate morphology(?+?)phase.The width of the slab morphology?increased to(3.63±0.41?m),and the aspect ratio(?9.1)decreased.And a small amount of fine secondary?phase precipitated from the residual?grains.In addition,when the temperature is below T?,a high solution temperature is beneficial to promote the decomposition of the??phase,and when the temperature exceeds T?,the content of the?phase decreases sharply.The comparison shows that the ST2 sample(955?/1h)has a large degree of??phase decomposition,a significant decrease in friction coefficient,and minimal wear.The wear mechanism consists of abrasive wear and adhesive wear at low load,and adhesive and oxidation wear at high load,and the wear morphology is more gentle.The area of plastic deformation is the largest,and the grains are greatly refined.In addition,it was also found that the hardness at the wear dent gradually decreases along the bottom of the dent toward both sides.In summary,the ST2sample with coarse phase?and?phase microstructure after solution treatment at 955?/1h has the best wear resistance.(2)The number and size of secondary?phases of the solid solution&different aging temperature samples increased,and the aspect ratio decreased.XRD detected the decomposition of the??phase into?and?phases and the precipitation of Ti₃Al(?2)particles.Dislocations disappear and the precipitation of Ti₃Al is promoted when the aging temperature is between 500-600°C.The comparison shows that the length and width of the secondary?'phase and the density of Ti₃Al particles precipitated from the SAT2 sample are the largest,the degree of?'phase decomposition is greater,and the peak of the?phase is the highest.The degree of wear is low.The damage mode is:20N is mainly damaged by abrasive particles;50N increased abrasive damage,accompanied by adhesion and slight oxidation,100N abrasive wear is reduced,and adhesion and oxidation are intensified.The Vickers hardness of the sample is greater than that of the solid solution sample,and the SAT2 sample has the highest degree of plastic flow and hardness.The above shows from different aspects that 955°C/1h solid solution&565°C/8h aging treatment has the best abrasion resistance.(3)The microstructures of the solid solution&different aging samples are all basket like structures,the acicular?'martensite is decomposed into(?+?)phase.A large number of fine secondary phase particles are precipitated from the?matrix,and the grain size increases first and then decreases with time.At the same time,the width of the plate morphology increased by 0.46?m,which tended to increase first and then decrease.In contrast,the length and width of the secondary?'phase and the density of Ti3Al particles precipitated in the SAT2 sample are the largest,the degree of?'phase decomposition is greater,and the peak of the?phase is the highest.The friction coefficient decreases with the increase of external load,and the SAT2 sample still has the lowest friction coefficient and low aspect ratio.It also has a smooth fish scale-like morphology.The wear mechanism is:low load abrasive grain wear,adhesive wear,and a small amount of oxidation,and high-load is mainly adhesive wear and oxidation wear.The above shows from different aspects that the abrasion resistance of SAT2 sample 955?/1h solid solution&565?/8h aging treatment is more outstanding.The above research conclusions revealed the effects of solution temperatures on the microstructure evolution and wear mechanism of Ti-6Al-4V samples prepared by SLM,and compared the solid solution temperatures with the best wear resistance.The microstructure evolution and abrasion mechanism of the sample with optimal solution temperature&aging treatment are revealed,and the optimal aging temperature and aging time of the sample under this test parameter are compared.It provides a certain reference value for the optimization of the wear resistance of Ti-6Al-4V alloy.