Research On Inconel625 Alloy Microstructure And Properties Using Wire Arc Additive Manufacturing Based On The Cold Metal Transfer(CMT)

Inconel625 nickel-based super-alloy has excellent strength and oxidation resistance in high temperature environments above 500?,which makes it widely used in aerospace,chemical industry,marine,nuclear energy and other fields.However,complex component structures and expensive processing costs have become significant factors restricting further development and application of Inconel625 super-alloys.Cold Metal Transfer Arc Wire Additive Manufacturing(CMT-WAAM)is a kind of processing technology that the materials are deposited layer by layer to manufacture metal components.CMT-WAAM uses electric arc as the energy-carrying beam and wire material as the filling material.Compared with traditional molding manufacturing methods(casting and forging),arc additive manufacturing has the characteristics of high depositing rate,low equipment cost,high material utilization rate and low heat input,which has attracted more and more attention to the manufacturing industry.Therefore,CMT-WAAM technology provides a solution to manufacture Inconel625 alloy with excellent performance at low cost and high efficiency.Based on the cold metal transfer arc wire feed additive(CMT-WAAM)manufacturing technology,this paper conducts research on the additive manufacturing samples of Inconel625 alloy.To improve the quality of additively manufactured components,the effects of sample microstructure of different height on the mechanical properties and corrosion resistance were mainly analyzed.In addition,in order to obtain better Inconel625 alloy properties,the method of applying an external magnetic field is used to improve the structure and mechanical properties of the CMT-WAAM Inconel625 samples.For optimizing the welding parameters in the CMT-WAAM manufacturing process,the effects of wire feeding speed(WFS),welding speed(TS)and welding torch angle(WTA)on the formation of single-layer welds were studied.And the optimum parameter was selected to carry out multi-layer additive manufacturing experiments.The microstructure characteristics of multi-layer deposited samples were analyzed.It was found that the microstructures of different deposition locations are different,which is mainly caused by the change of heat accumulation and cooling rate.Different microstructures also resulted in anisotropy of the sedimentary samples.As the height increasing,the tensile strength increased,and the ultimate tensile strength of top,middle and bottom are 691 MPa,683 MPa,and 662 MPa,respectively.The elongation rates show opposite trends(top region: 43.47%,middle region: 45.2%,bottom region: 48.8%).In addition,the corrosion resistance of different height regions was also different,of which the corrosion resistance at the top is the best,and the corrosion resistance of the bottom is the worst.These were mainly attributed to the difference in the different microstructure,crystal spacing and corrosion-resistant metal element content.Finally,the effect of the external magnetic field on the microstructure and mechanical properties of the deposited sample was studied.The influence of the magnetic field on the arc shape and the molten pool was analyzed and the mechanism of the effect on the microstructure was explored.The results showed that the magnetic field can effectively refine the grains,change the microstructure orientation,and stifle the segregation of alloying elements,thereby improving the performance of the additive samples.