Study On Additive Manufacturing Technology Of Heterogeneous Materials For Body Stamping Die

Mold is an important process equipment in automobile manufacturing.Zinc alloy mold has the advantages of good plastic processing performance,short processing cycle and low cost.However,the low hardness and poor wear resistance of zinc alloy die make it easy to wear at the corners,which affects its service life.In this paper,through additive manufacturing technology in zinc alloy mold local preparation of zinc steel heterogeneous structure,so as to solve the problem of zinc alloy mold corner wear resistance,low strength,improve the service life of zinc alloy mold.Because the melting point and boiling point is very different between zinc and steel,the vaporization of zinc can be caused by directly adding materials to zinc alloy to make steel.In this paper,arc spraying technology is introduced into additive manufacturing.Firstly,a copper transition layer is prepared on zinc alloy by arc spraying,and then the steel structure is prepared on the transition layer by laser selective melting and laser metal deposition.In view of the problems in the experiment,four kinds of technology are used in the experiment:(1)The copper coating is sprayed and then the laser selective melting and material addition is used.The process can realize the good combination of zinc steel interface,but because the experimental equipment limits the powder thickness,it is difficult to control accurately,so the improved technology is proposed.(2)First,copper coating is sprayed,then fixed thickness steel coating is sprayed.Finally,the composite coating is remelted by laser directly.Because the laser selective melting is not suitable for the manufacture of large-scale structural parts,the laser metal deposition method is adopted to improve.(3)After arc spraying copper coating,laser metal deposition experiment was carried out on the substrate material.But it is difficult to stack metal powder directly on its surface under this method,so we should improve the process.(4)Three steps of coating copper coating spraying steel thin layer laser metal deposition steel powder are adopted.The existence of steel coating can effectively improve the absorption rate of laser on the surface during cladding process,and improve the fusion between copper and steel,and achieve the best effect.The influence of the thickness of the transition layer and laser parameters on the process of the material addition is studied in this paper.The hardness test and metallographic observation are used to analyze the experimental results.The results of single pass laser selective melting experiment in scheme(1)show that the height and width of cladding steel decrease with the increase of laser scanning speed and copper layer thickness;The bath depth and width of zinc layer decrease accordingly.With the increase of laser power and the decrease of copper layer thickness,the height and width of cladding iron increase;The depth and width of zinc bath increase correspondingly.The results of metallographic microscope and electron probe show that the copper layer plays a good role as a bridge in the process of zinc alloy cladding steel structure.After arc spraying,the interface between copper and zinc is mechanical occlusion.Through the analysis of metallographic structure,it is found that the interface between steel and copper is well bonded,and orange yellow substance is formed between copper and zinc;The results show that the grain size of zinc is refined,the hardness is improved,and a good metallurgical bond is formed between copper and zinc.The hardness test results show that the Vickers hardness of the zinc alloy matrix is only 50 Hv,while the hardness of the steel structure with surface additive accumulation can be increased to 360 Hv.Using additive manufacturing process can effectively improve the local hardness of zinc alloy,which has a significant role in improving the service life of zinc alloy mold.