Study Of Microstructure And Properties Of Ti6Al4V Alloy By Selective Laser Melting

Selective Laser Melting(SLM)is a new technology widely used in manufacturing,wich can form structural parts with complex shapes,high precision and save raw materials.Ti6Al4V alloy is widely used in automotive,aerospace,Marine,biomedical and other industrial fields due to its low density,high specific strength and good biocompatibility.Due to the timeconsuming and difficult processing of titanium alloy components by traditional processes,it has become a trend to use the SLM technology to form titanium alloy components.However,the titanium alloy components formed by SLM generally have the problem of poor plasticity,so it is necessary to study this to improve its comprehensive mechanical properties.Since the titanium alloy components prepared by SLM need to be used in harsh environments such as marine ships,it is important to improve their corrosion resistance.In addition,due to the poor wear resistance of Ti6Al4V alloy,the service life of the component is seriously reduced,so it is imperative to improve its wear resistance.In summary,this thesis will use the SLM technology to study the mechanical properties,corrosion resistance and tribological properties of Ti6Al4V alloy by element doping method.Firstly,the effects of 5%and 8%Cr powders on the microstructure and properties of Ti6Al4V alloy prepared by SLM were studied,in order to improve the plasticity of SLM forming parts.Compared with Ti6Al4V alloy,the compressive strength and plastic strain of Ti6Al4V+5Cr alloy are increased by 7.73%and 26.32%respectively,and the plastic strain of Ti6Al4V+8Cr alloy is increased by 47.2%.In addition,the corrosion resistance of Ti6Al4V-Cr system alloys are gradually enhanced with the increase of Cr content.Therefore,the addition of an appropriate amount of Cr powder can significantly improve the plasticity and corrosion resistance of Ti6A14V alloy.Secondly,the effect of nano-Nb particles on the microstructure and properties of Ti6Al4V alloy prepared by SLM was studied,in order to improve the corrosion resistance of SLM forming parts.The elongation and plastic strain of the alloy increased by 2.43%and 8.64%respectively after the addition of nano-Nb particles,and the tensile strength and compressive strength were simultaneously improved without reducing the elongation and plastic strain.Combined with potentiodynamic polarization curve and impedance spectrum,it is concluded that the corrosion resistance of Ti6Al4V+1Nb alloy is better than that of Ti6Al4V alloy.Finally,the effect of 1%nano-WC particles on the tribological properties of Ti6Al4V alloy prepared by SLM was studied,in order to improve the wear resistance of Ti6Al4V alloy.The results show that compared with Ti6Al4V alloy,Ti6Al4V+1 WC alloy has finer grain size and higher hardness,which promotes the alloy to obtain smaller friction coefficient and wear rate,and improves its wear resistance.The wear mechanism is abrasive wear and adhesive wear.Therefore,the addition of nano-WC particles can improve the wear resistance of components and prolong its service life.