Effect Of Al Content On Microstructure And Properties Of TC4 Fabricated By Laser Additive Manufacturing

Laser additive manufacturing is an manufacturing technology that rapidly emerged in the 1990 s.Its design three-dimensional CAD target graphics through computer,use the "discrete + stacked" forming concept,and selectively melt and deposit by laser to manufacture the final functional parts.This processing method can not only shorten the production cycle,reduce the production cost,but also can produce parts with high performance requirements and complicated structure compared with the traditional processing methods.As a common industrial alloy,TC4 alloy has the characteristics of good corrosion resistance,high specific strength,excellent high temperature mechanical properties,and is widely used in various fields of production and life.However,in some special fields,especially in the aerospace field,the mechanical properties of TC4 alloy are not stable enough to meet the requirements for use,resulting in its application being limited.Therefore,use new laser additive manufacturing technology to optimize the comprehensive mechanical properties of TC4 alloy is particularly important.In this dissertation,TC4 alloy specimens with different Al addition were obtained by laser rapid forming,combined with X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),microhardness tester,friction and wear tester,compression tester,and electrochemical workstation are used to test Its performance.Analyze the alloy microstructure and change law,in order to obtain good formability,excellent overall performance of the new laser additive manufacturing TC4 alloy.Analyzed by XRD,SEM,and TEM results to determine that the phase composition of the alloy after laser forming is ? phase and ? phase,and the number of ? phases is much greater than that of ? phase.During the experimental process,as the Al addition increases,making the contact angle gradually decrease,the height of the deposition layer decreases,and the width increases.At the same time,since Al is a stable element of ? solid solution,the amount of ? phase gradually increases with the addition of Al,but the grain size decreases first and then increases,the lattice constant decreases gradually,and eventually the hardness gradually increases.Reinforced,wear resistance gradually increased,but the plastic deformation capacity of the material increased first and then decreased.Combined with the results of electrochemical corrosion experiments,it can be seen that with the increase of Al addition,the comprehensive mechanical properties of the TC4 alloy tend to improve within a certain range,but when the Al addition more than 1.5wt.%,the plasticity and corrosion resistance of the material are reduced to varying degrees.