Research On Technology And Toughness Enhancement Of Plasma Arc Additive Manufacturing For High Strengh Steel

Based on robotic plasma arc additive manufacturing technology,the ER130S-G highstrength steel was used as the research objects.The forming process and toughening of plasma arc additive manufacturing for high strength steel were studied.Design-Expert software was used to model and optimize the forming dimension of singlepass multi-layer straight wall.The mathematical expressions between the optimized layer width and height and process parameters were obtained.Aiming at the influence of width-height ratio of weld bead on the lap flatness of high strength steel,the relationship between lap rate and flatness under different width-height ratio was obtained by polynomial fitting curve.When a large aspect ratio was adopted,such as 11.61 in this paper,a better smoothness of the deposited layer can be obtained.The effects of depositing current,wire feeding speed and interlayer temperature on the microstructures and mechanical properties of high strength steel arc additive manufacture were studied.The results show that the tensile strength under different depositing current was over 1000 MPa,and the impact resistance and elongation in Y direction(along deposit velocity direction)was higher than that in X direction(vertical deposit velocity direction).Compared with 90 A current,the elongation increasesd by 167% and the impact toughness was increased by 11.11%.when 110 A current was applied.When the interlayer temperature was 40 ?,the elongation increases by 47.83% and the impact toughness increases by 19.81% compared with that at 120 ?.When the wire feeding speed was 0.75m/min,the tensile strength increases by 10.91%,the elongation increases by 228.91% and the impact toughness increases by 45.98% compared with that at 1.05m/min.The effects of one-word path,one-word reciprocating path and cross overlapping path on the microstructure and mechanical properties of high strength steel additive blocks were studied.It was concluded that the farther away from the substrate,the higher the impact resistance was.At the same time,the strength,plasticity and toughness of one-word path and one-word reciprocating path were not very different,but the tensile strength increases by 10.13% and 10.69% compared with the one-word path and the one-word reciprocating path.At the same time,the toughness increases by 9.30% and 10.59% respectively.In order to further strengthen and toughen the three-dimensional block,a small amount of stainless steel soft material was added to the high-strength steel matrix to realize the interweaving toughening.The results show that when two layers of stainless steel were separated by two layers of high strength steel,the tensile strength decreased by only 3.05%,but the elongation and impact toughness increased by 31.63% and 11.36% respectively.