| Wire Arc Additive Manufacture is based on arc as the heat,welding wire as the add material,rapidly and directly forming the structure part with high density and excellent mechanical properties.This subject is based on controlled arc(plasma arc)and focus on the additive manufacture experimental process research,for TC4 titanium alloy and TA1 industrial pure titanium as two kinds of additive materials.The influence of process on the single deposition bead's form quality and macro-geometrical dimension was analyzed,and the optimized additive process parameters and the weld bead model were carried out.And then the experimental research on the typical bionic interlaced structure of these two materials by plasma arc additive manufacture was carried out to explore its superior mechanical properties.Firstly,according to the forming characteristics of the single deposition bead of two kinds of materials,the process parameters windows for the single-bead forming quality of the two materials were obtained,and the effect of process parameters on the macro-geometric dimensions of the two materials was also studied.The influence of current,wire feeding speed and traveling speed on TC4 single deposition bead geometrical dimension is obvious,while the TA1 single deposition bead geometric change is obviously influenced by current and wire feed speed but the influenced by traveling speed is not obvious.Further,study the weld bead cross-section profile model of the two kinds of materials in a fixed current and different deposition ratio,and according to the matching error of size and profile area to select the additive process parameters.The results show that the single bead cross-section profile model is fitted to a parabolic function when the current of TC4 is 125A and the current of TA1 is 140A,and through the multi-overlap model calculation and experimental verification which got the TC4/TA1 dissimilar materials overlap as well as the TC4/TC4 same material overlap optimal spacing is d1*=d2*6.58mm,and the optimal overlap spacing of TA1/TA1 is d3*= 6.54mm.The research on multi-layer interlaced straight wall shows that the tensile strength of straight wall with interlaced structure of four different ratio of materials is slightly less than that of TC4,the elongation after break is the same as TC4,and the longitudinal tensile strength is less than its transverse tensile strength.With the increase of the proportion of TC4,the longitudinal tensile strength of the interlaced structure shows a downward trend.The tensile fractures of the interlaced structure straight wall shows mixed fracture characteristics including dimple fracture,quasi-cleavage fracture and cleavage fracture.The microstructure is highly diversified,which are lamellar a with consistent orientation and parallel to each other,small baskets in the inner part and residual ?,etc.The TA1 deposition microstructure presents the characteristic ?-rich area of the typical two-phase structure due to the diffusion speed of Vanadium in ? phase is higher than that of Aluminum,which reduced the ? transition temperature in TA1 deposition.Finally,the impact performance of the interlaced structure of TC4 and TA1 were tested and the result shows that the top impact absorption work of the three interlaced structures all increased by more than 35%,which compared with that of TC4,and the SEM found that the direction of expand crack deflection along the different materials' fusion interface,which validated the practical feasibility of using additive manufacturing technology to quickly shape the interlaced structural materials with both high strength and high impact resistance. |
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