Study On TC4 Titanium Alloy Cold Metal Transition Welding And Numerical Simulation Of Additive Manufacturing Process

Wire and arc additive manufacture based on the welding process is a new technology for rapid prototyping metal parts,which has the advantages of low cost and high efficiency.The traditional welding process has a poor effect on the wire and arc additive manufacturing of TC4 titanium alloy.To solve this problem,it is planned to use the emerging cold metal transition welding technology to conduct the wire and arc additive manufacturing experiment on TC4 titanium alloy,and use ABAQUS simulation software to analyze the temperature field and stress field of the additive manufacturing process.This paper builds a CMT welding platform and cooperates with high-speed camera and electrical signal synchronous acquisition system to collect droplet transition images and current and voltage signals,and analyzes the droplet transition and electrical signal changes of two different CMT welding modes at different wire feed speeds.The analysis of the electrical signal found that in the DC CMT welding mode,as the wire feed speed increases,the peak current increases by a larger amount,and the secondary peak current increases by a smaller amount.The increase in wire feed speed also leads to a significant increase in the size of the droplets and deteriorates the weld formability.The welding parameters are not suitable for additive manufacturing.In CMT+P welding mode,the welder controls the heat input by changing the current base value or the number of pulses or both.This welding mode has good weld forming properties,with a preferred wire feeding speed of 4 m/min and a welding speed of 0.4 m/min,and simulation of additive manufacturing is performed under this welding parameter.This paper also uses the ABAQUS software to establish a numerical model of CMT additive manufacturing under optimized parameters,and analyzes the temperature and stress fields during the wire and arc additive manufacture process.Analysis of the temperature field revealed that during the single-layer stacking process,with the increase in the length of the surfacing,the heat dissipation conditions around the molten pool become worse,and the peak temperature of the molten pool will increase slightly.In the multi-layer stacking process,as the number of stacked layers increases,the temperature curve on the basal plate exhibits a cycle of peaks and valleys,the temperature curve gradually smoothes,the peak value gradually decrease,and the valley value gradually increases,and heat accumulation phenomenon appears.The analysis of the stress field found that during the single-layer accumulation process,due to the strong heating effect of the arc around and in front of the weld bead,the equivalent stress will be mainly concentrated in front of the weld pool and on both sides of the weld bead.In the process of multi-layer stacking,the heat accumulation inside the formed part reduces its equivalent stress.As the number of stacked layers increases,the peak value of equivalent stress on the basal plate gradually decreases,and the valley value gradually increases.After the specimen is completely cooled,the equivalent stress value increases significantly.