Peocess Research Of Auxiliary Wire Feeding Gma Additive Manufacturing And Fabrication Of Graded Material

Gas metal arc additive manufacturing(GMA-AM)as a widely used metal additive manufacturing method,has a series of advantages such as simple equipment,low production cost and high deposition efficiency.However,there are some disadvantages including heat accumulation and homogeneous composition in same wire.Aiming at the above disadvantages,a new auxiliary wire feeding GMA-AM process is proposed.The arc and the remaining heat of the molten pool melt the auxiliary welding wire.The heat input to the base metal is reduced while the deposition efficiency is increased;when using a heterologous auxiliary wire,the composition of deposited metal can be controlled by adjusting the auxiliary wire ratio,a new graded material preparation method is provided.This paper focus on the process characteristics of GMA-AM,the main content is the influence of the auxiliary wire on the forming and heat input of the deposited bead.The variation of the deposited bead profile and deposition dimension is analyzed,also establishes the regression model.The microstructure and properties of the heterogeneous auxiliary wire feeding are studied,which lays a good foundation for the arc-based additive manufacturing of graded materials.The effects of the process parameters such as feed direction and feeding speed of the auxiliary wire and deposit velocity on forming are studied,also obtain the process parameter range for excellent forming appearance.Tests show that with the use of an auxiliary wire in front of the molten pool and the auxiliary wire speed within 40% of the total wire feed speed,a well-formed weld can be obtained.At the same time,the auxiliary wire process can reduce the area of HAZ by 35% and the peak temperature of the thermal cycle by about 40℃.The deposited bead profile and dimension are further studied and obtain the forming variation of the bead and establish quadratic regression model between the process parameters and bead dimension.It is found that when the deposition current and the deposition rate are small,and the auxiliary wire feeding speed is large,the profile of the deposited bead turns into a spherical shape,which is not conducive to accumulation.At the same time,the regression model shows that the auxiliary wire feeding speed has no significant effect on the width of the deposited bead.The width range of the process is 4.8~10.6mm,and the height adjustment range is 2.0~5.3mm,which provides a basis for the slicing and planning of the formed parts.By adjusting the proportion of heterogeneous auxiliary wire to adjust the composition of the deposited bead,a single wall of different compositions accumulated,and the microstructure and mechanical properties of the samples are tested.The results show that with the increase of the proportion of H06MnNi3CrMoA,the amount of granular bainite and acicular ferrite increases in the microstructure,and the tensile strength and microhardness of the mechanical properties increase.The adjustment range of tensile strength is 550-880 MPa,and the hardness adjustment range is 210-390 HV,providing the foundation for performance control.A single-wall and induced-gear model with component gradients is designed and planned.It is prepared using auxiliary wire feeding GMA additive manufacturing process.The results showed that the structure and performance gradients of the formed parts are in line with expectations.