Process And Property Study On Wire Arc Additive Manufacturing Of 5B06 Aluminum Alloy

With high deposition efficiency and low equipment cost,wire arc additive manufacture(WAAM)is becoming an important development direction for manufacturing large-scale aluminum alloy.However,the layer upon layer manufacturing process contributes to non-uniform microstructure,that leads to poor mechanical properties,which further restricts the popularization and application of WAAM.In order to improve the comprehensive performance of aluminum alloy parts manufactured by WAAM,this project conducted in-depth study of many processes,including the effect of mechanical vibration and arc oscillation on as deposited 5B06 aluminum alloy,in order to investigate the variation characteristics of macro forming? microstructure and mechanical property,and make analysis on the related mechanism.The main results are listed as follow:The single-bead forming characteristics of four cold metal transfer(CMT)arc modes has been studied.With better spreading effect,CMT+P mode is suitable for bottom forming,but CMT+P +A mode is more suitable for forming thin-walled parts since that its forming heat input is lowest among the four arc modes and owning sound welding stability.The forming porosity can effectively reduced to 0.3% by using statistical optimization method which brings optimum combination of process parameters.By introduce general rotatable design,the effective width of as deposited parts can be well predicted,the prediction accuracy is nearly 90%.The effective width percentage of as deposited thin-walled parts mainly remain in 75~85%,no matter which process adopted,including mechanical vibration and arc oscillation.Meanwhile,arc oscillation can increase the effective width of the as deposited thin-walled parts.For microstructure,the as deposited 5B06 aluminum alloy displays obvious periodic change along the additive manufacturing direction: in molten pool region,the size of precipitated phase and grain is small,while the adjacent transigion region owning large size precipitated phase and grain.The grain in CMT+P arc mode show obvious columnar crystal transition characteristics,which leads to decreased transverse tensile property compared with other three arc modes that the microstructure are mainly equiaxed crystal.In CMT+P+A mode,different heat input and inter-layer waiting time has little effect on tensile properties and related anisotropy.The vibration process could remarkable refine the coarse grain in transition region of the thin-walled parts,and further make the microstructure uniform between adjacent layers.When test with mechanical vibration(vibration accelation reaches 15m/s2),the horizontal and vertical tensile property could averagely improve 20~30MPa.Arc oscillation helps to improve the mechanical property anisotropy of the as deposited thin-walled parts.Compared with no oscillation,when the transverse arc oscillation frequency reaches 7.5Hz,the tensile property anisotropy could reduce from 17.88% to 8.24%.