| 0Cr15Ni5Cu2Ti steel is a new type of martensitic precipitated hardening stainless steel with excellent properties.It has been used more and more in new ships,aerospace and other fields.Some aircraft parts made of 0Cr15Ni5Cu2Ti steel usually work in the corrosive environment of high temperature and high humidity.In order to further improve the corrosion resistance,wear resistance and high temperature oxidation resistance of the steel,salt bath nitride,gas nitride and multi-arc ion plating Tialsin coating were used to modify the surface of the steel.And its structure and performance were tested and analyzed.The results are as follows:(1)0Cr15Ni5Cu2Ti steel salt bath nitriding.Taking nitriding temperature,nitriding time and cyanate concentration as variables,three levels were taken for each factor,and an orthogonal experimental scheme of L9(34)was designed.The optimized process parameters obtained by orthogonal test were as follows:nitriding temperature 520?,nitriding time 80min,cyanate concentration 34%.Under these conditions,the surface hardness is 1100.7HV0.2,the depth of nitriding layer is 29.66?m,the oxidation weight gain is 20%of the substrate,the friction coefficient is reduced by 0.23,the wear amount is 17.5%of the substrate,the corrosion voltage is-0.27416V,the corrosion current is 4.5519×10-6A/cm2,the corrosion rate is 0.052957mm/a,compared with the substrate,the corrosion voltage is increased by 0.03V,the corrosion current density is reduced by0.5×10-6A/cm2.(2)Gas nitriding of 0Cr15Ni5Cu2Ti steel.Two kinds of equipment,the common well type gas nitriding furnace and the vacuum gas nitriding furnace,were selected,and four different technological schemes were used for the test.After testing and comparing its performance,scheme 4 is the best,scheme 1 is the second,and scheme 3 is the worst.Scheme 4 is vacuum gas nitriding,and its technological parameters are as follows:nitriding temperature 520?,nitriding time 32h,vacuum degree-10?-20mbar.The temperature of the first and second stages of nitriding is515±5?,and the duration is 13h.The temperature of the third stage is525±5?and the duration is 19h.Under the process conditions,the surface hardness of 868.8HV0.2,nitriding depth 16.36?m,oxidation weight increase is 24%of the base material,reduce the friction coefficient of 0.07,the wear quantity is 20.5%of the base material,corrosion voltage of 0.22416V,the corrosion current density of 4.3519×10-6A/cm2,and corrosion rate was0.051957mm/a,compared with the base material,corrosion voltage increased 0.05V,the corrosion current density decreased by 0.7×10-6 A/cm2.(3)Multi-arc ion coating on 0Cr15Ni5Cu2Ti steel.The Ti Al Si N coating was selected as the working layer according to the preparation method of the coating studied by the research group.Process parameters:target current of 60A,matrix bias of-100V,duty cycle of 50%,N2 gas flow rate of 50sccm,matrix temperature of 260?,deposition time of 120min.Under these conditions,the surface hardness is 1971.4HV0.2,the coating thickness is 3.8?m,the oxidation weight gain is 32%of the substrate,and the film/substrate bonding force is 10N.(4)The comparative analysis shows that the three surface modification methods of salt bath nitride,gas nitride and multi-arc ion coating have certain influence on the surface hardness,high temperature oxidation resistance,wear resistance and corrosion resistance of0Cr15Ni5Cu2Ti steel.Salt bath nitriding is the most obvious improvement in high temperature oxidation resistance,and the surface hardness of Ti Al Si N coating is the highest.Salt bath nitriding and gas nitriding can obviously improve the wear resistance and corrosion resistance of0Cr15Ni5Cu2Ti steel,and gas nitriding sample has better corrosion resistance. |
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