Research On The Influence Of GTAW Process Parameters On TC4 Titanium Alloy Forming Precision

Titanium and titanium alloys,owing to their low density,high strength and corrosion resistance,have been identified as one of the most promising metal structural materials in the aerospace industry area.However,the traditional manufacture method of titanium alloy is inappropriate,and the low utilization of materials in traditional methods always leads to prohibitive cost.Therefore,arc additive manufacturing technology for titanium alloy has received widespread attention,and how to improve its precision is a further challenge.However,research on this aspect at present is in the initial stage in domestic.This topic comes from CASIC,Harbin Fenghua company’s project,named "Research on the key technology of titanium alloy arc additive manufacturing".This topic based on gas tungsten arc welding(GTAW)method,and TC4 titanium alloy was the research object,and analysed the effect of pulse current parameters and parameters related to the heat input to the forming accuracy respectively,in order to provide theoretical basis for high quality forming of GTAW process.Firstly,through analysis of arc additive manufacturing technology research status and forming experiment requirement,a Cartesian robot was designed with the relevant corollary equipment.Meanwhile,through summarizing the evaluation indexes of GTAW forming precision by domestic and foreign scholars,the effective ratio evaluation indexs was proposed for single-layer forming and multi-layer forming respectively.Secondly,through a mass of literature summary,this text summarized the interactive influence between various parameters on forming precision,and found that reduce the impacts from the droplet to the weld pool and maintain stability of the weld pool could improve the forming precision.A "quality-spring" system was established based on the prior discovery,which was used to test the influence of pulse parameters to the droplet state with the software Wolfram Mathematica.At the same time,the Finite Element Eethod was used to studying the thermal input parameters on the single-layer and multi-layer forming heating process respectively,through studying the effect of heat input parameters on the viscosity of the weld pool,and the effect of pulse parameters on forming precision is obtained.Finally,this text designed three groups of GTAW forming experiment using BBD design of Response Surface Method.The first group was to confirm the pulse current parameters affects the forming accuracy by influencing the droplets state,the second group was to confirm the heat input parameters affects the accuracy of single-layer forming by influencing the viscosity of weld pool,and the third group was to confirm the heat input parameters affects the accuracy of multiple-layer forming by influencing the viscosity of weld pool.For the forming results,the software Design-expert was effectively used to analyze the significance of the related parameters,and made the linear regression equation.Ultimately,summarized the impact law of the parameters on the forming results,and provided relevant parameters range for superior forming precision.