Properties And Characterization Of Metal Matrix Nanocomposites Components By Additive Manufacturing And Following Upsetting And Stretching

The mechanical properties of traditional ways（forging,upsetting,stretching,etc.）forming metal components depend on the thermal history dependence of the internal microstructure.Additive manufacturing forming components are more complex,which make their mechanical properties and durability different from those of the former.The laser additive manufacturing technology of high performance metal component with alloy powder or wire material as raw material,metal components are formed by high power laser in situ metallurgical melting/rapid solidification by packing layer by layer.It is possible to prepare an excellent forming component on the substrate surface by selecting the appropriate cladding material and laser forming under suitable technological parameters.The defects such as porosity,porosity and lack of fusion resulted in the reduction of the properties of conventional metal LAM.In order to eliminate the above defects and further improve the performance of the components made by LAM technology,this paper introduces the upsetting and stretching process to make cold deformation of the forming components and achieve the purpose of deformation strengthening.On the basis of previous research,this subject has formed two kinds of composite forming parts 316L+10%SiC and 316L+6%Al₂O₃ by laser cladding technology on the316L substrate.High temperature metallographic microscope（Axio Scope A1）was used to carry out high temperature metallographic observation at high temperature.Subsequently,the 0,1,2 and 3 times upsetting and stretching experiments were carried out on the self-developed hydraulic system to produce plastic deformation.After upsetting and stretching process,metallographic specimens were observed using a conventional optical microscope（OM,Axio Scope A1）.The phases of the polished coatings were identified by an X-ray diffractometer（XRD,Phillips Rayons-X）.Micro-hardness was measured on a Vickers micro-hardness testing machine（HVS-5）.Uniaxial tensile test was conducted on Zwick Z100/SN5A electronic universal testing machine.The detailed microstructure of fractured appearance was observed by scanning electron microscopy SEM.The detailed twins and dislocation microstructure was observed by transmission electron microscope（TEM,JEM-2010）.Dry sliding wear test was performed on the CETR UMT-3block-on-ring apparatus at room temperature without lubrication.The purpose is to observe whether the specimens formed by laser forming will be deformed and strengthened by cold deformation,so as to further strengthen the surface and internal properties of the specimens.The results show that the surface properties of the specimen after the upsetting and drawing process has been further improved.This subject has high theoretical significance and practical application value.