Forming And Numerical Simulation Of Austenitic Stainless Steel 304 Based On CMT-WAAM Technology

Comparing with traditional manufacturing,Wire Arc Additive Manufacture(WAAM)technology was based on Cold Metal Transfer(CMT)has attracted much attention of the industry for its small heat input,less spatter,and low equipment cost.It uses arc as the heat source and metal wire as filling material to make metal parts by depositing material layer by layer.Because austenitic stainless steel 304 has a wide range of applications,its mechanical and physical properties are better,and the emergence of CMT-WAAM technology provides a new opportunity for austenitic stainless steel 304 additive manufacturing and development.Based on CMT-WAAM technology,the arc additive manufacturing process and deposition samples of austenitic stainless steel 304 were studied.The influence of the process parameters on the mechanical properties of the deposited samples of the manufacturing process is investigated.Simulations are also used to control the size of heat input during the additive manufacturing process to improve the forming quality and control the range of high-temperature regions during the additive manufacturing process.First,the influence of welding speed and wire feeding speed on single-layer single-pass deposition is studied,and the single-pass single-layer additive manufacturing process is simulated.The heat source parameters and the reliability of the finite element model is determined by heat source verification.The influence of welding speed on the temperature field and the size of the area above the melting point of austenitic stainless steel 304 during the additive manufacturing process is analyzed.Next,suitable process parameters were selected for single-pass multilayer additive manufacturing for simulation.The effects of deposition direction,interlayer residence time,and heat input efficiency on the single-pass multilayer additive manufacturing process were investigated in focus.It was found that different deposition orientations affect the temperature and stress fields in the fabrication process.The temperature field of unidirectional deposition is asymmetrically distributed and there is a thermal concentration effect of the closing arc end;the stress field of reciprocal deposition shows the symmetrical distribution,and the temperature field is more uniformly distributed over less residual stress.Increasing the interlayer residence time and changing the heat input efficiency can effectively reduce the interlayer temperature,decrease the size of the high-temperature region,and reduce the residual stress.Finally,single-pass multilayer deposited samples were tested using suitable process parameters.The mechanical properties and metallographic organization of the single-layer single-pass and single-layer multi-pass deposited samples were analyzed.The results showed that the tensile strength and hardness gradually weakened,and the tensile rate increased as the distance from the substrate increased.The solidification mode of 304 austenitic stainless steels in the arc additive manufacturing process was analyzed as FA mode.