Numerical Simulation On The Temperature And Stress Fields Of Wire Arc Additive Manufacture For Duplex Stainless Steel And Process Optimization

WAAM(Wire Arc Additive Manufecturing)technology is a novel one,to print the metal parts by hardfacing,whose heat source is arc.The features of WAAM are low cost equipment,high efficiency and size wide range of additive manufecturing.Numerical simulation method based on finite element theory is a effective one,to simulate the actual working conditions by software,whose features are low cost and short period.ER2209 duplex stainless steel with ferrite and austenit,is widely used in the fields of architecture,ocean and chemical industry.In this paper,the ANSYS software was taken as the simulation software and ER2209 duplex stainless steel as the research material.The temperature and stress fields during the process of WAAM,and the shape and performance of the metal parts were analyzed.The temperature and stress fields were simulated in WAAM process by ANSYS Software.Meanwhile,They were measured by multi-channel temperature measuring system and X-ray stress instrument,respectively.The experiment is guided by the result of simulation,and the metal parts of well shape are printed by WAAM system.The microstructure and properties of the matel parts were analyzed by optical microscope(OM),X-ray diffraction,scanning electron microscope(SEM),universal tensile tester,Vickers hardness tester,nanoindentor and electrochemical workstation.The orthogonal experiment was used to determine a set of process parameters,which can stabilize the arc and smooth the surface of the matel parts.The voltage of WAAM is 23 V,the speed of WAAM is 200mm/min,and the speed of wire feeding is 11m/min.By using the accurate model analysis,the maximum temperature appears at the end of WAAM matel part.With the decrease of temperature,the stress field increases gradually.When the temperature drops to room temperature,the maximum stress value is 445 MPa,which is lower than the tensile strength.so the crack can not appear on the surface of the matel parts.When the ER2209 duplex stainless steel is used as WAAM material,the temperature field increases with the increase of the WAAM voltage,current and the number of layers,and decreases with the increase of interlaminar cooling time and the increasing rate of WAAM.The same direction WAAM matel part is easier to collapse than the reverse one.Water cooling can obviously reduce the accumulation of temperature field.With the increase of the number of layers,the distribution of the equivalent stress on the matel part is not uniform,and the maximum equivalent stress is basically unchanged.When cooling mode is different,the distribution of equivalent stress on the matel part is basically uniform,and the maximum equivalent stress of water cooling is larger than that of air cooling.The temperature of the underlayer edge does not exceed the melting point as the standard of the matel parts not to collapse.The relationship between increment of per layer and the average temperature of cooling is that the increment of per layer of air-cooling reduce from 3.25 mm to 2.37 mm and that the increment of per layer of water-cooling reduce from 3.62 mm to 2.38 mm.When the ER2209 duplex stainless steel is used as the experimental material,there are only ferrite and austenite phases in the microstructure,and no Sigma phase can be produced.The microstructure of WAAM parts is not uniform,the content of ferrite in air-cooled state is decreased from 40.49% to 21.76%,and the content of ferrite in water-cooled state is decreased from 45.37% to 30.54%.The difference of tensile strength between different regions of the matel parts manufactured by WAAM is 68 MPa.The difference of elongation between different regions of the matel parts manufactured by WAAM is 6.5%.The difference of hardness between different regions of the matel parts manufactured by WAAM is 10 HV.The difference of hardness between different regions of the matel parts manufactured by WAAM is 10 HV.The difference of pitting potential between different regions of the matel parts manufactured by WAAM is 0.4V.By solution treatment,the structure of the parts is basically uniform.