| 3D printing is a new material forming technology,which has unparalleled technical advantages over traditional processing methods.Due to the relatively high melting point and stable chemical properties of metal materials,the difficulty of printing process is much more than that of polymer materials.The existing metal printing scheme has the problems of high equipment cost,nearly demanding material requirements and congenital stress defects,which hinders the large-scale application and promotion of metal 3D printing.In view of the existing technical problems,we propose a new 3D printing scheme of metal injection molding(3D printing of metal injection molding),which ingeniously combines the existing metal powder injection molding(MIM),additive manufacturing and powder metallurgy sintering technology,makes full use of the advantages of each technology,and can realize the forming of complex structure with high efficiency,which is a new one with great development value and promotion potential Metal 3D printing solution.In this paper,316L stainless steel is taken as the research object,and the microstructure and element analysis of the printing wire are carried out,and the optimal printing temperature and speed are obtained through the gradient experiment.The 316L stainless steel samples were studied for density,shrinkage,surface roughness,metallographic structure and mechanical properties to obtain the best print quality processes and methods.Through the tensile experiment,the tensile curve of each printing parameter sample was obtained,and then its static mechanical performance parameters were obtained.The yield strength of the sample at 0.1mm printed layer height reached 188 Mpa,the tensile strength reached 501 Mpa,and the elongation was surprising It reached 87%,which proved that the samples processed by metal injection molding 3D printing technology had good mechanical properties.At the same time,the fracture morphology is studied to explore the crack propagation mechanism during the fracture process.The hardness test reveals the correlation between the hardness of the material and the printing parameters.Fracture toughness verify the feasibility of increasing the ability of the material to resist fracture by adjusting the appropriate processing technology.Three typical paths are selected for printing,and the size shrinkage,density and mechanical properties of the sample after molding are measured.It is found that the ± 45 ° cross-printing has a woven structure,which has a certain retarding effect on the plastic deformation of the material and makes it able to withstand more Large load;the sample printed in parallel at 0 °has the best material continuity,so that it has the maximum elongation;The joint surface of the workpiece processed by the 90 ° printing method has a mechanically weak area,and the performance is poor.Through the research on the filling rate of materials,it is proved to a certain extent: on the premise of ensuring the use performance,the appropriate filling rate can be selected to reduce the use of materials as much as possible,so as to achieve the perfect combination of performance and structure quality.After replacing the large-diameter nozzle,the large-sized gap becomes a mechanically weak zone during the stretching process,and the original crack source is formed after the load is applied,which adversely affects the mechanical properties of the material.At the end of the article,the application of metal injection molding 3D printing technology was studied.Around the three aspects with the highest potential for application,a batch of highly characteristic samples were printed,mainly including porous honeycomb materials for the field of exhaust gas catalysis and heat exchange.Flexible movable dragon heads,bracelets,etc.,as well as blade models of different sizes and shapes and mold parts with internal complex through channels,have proved the feasibility of metal injection molding 3D printing technology in this regard. |
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