Experimental Study On High Nitrogen And Stainless Steel Layered Overlap Structure Of Robot Plasma Additive

This paper is based on plasma arc additive manufacturing process.Testing the high-nitrogen steel and stainless steel single-channel additive large width-height ratio process.Study whether it is possible to improve the surface flatness of plasma additive forming parts by reducing the weld bead height and increasing width-height ratio,and further study whether the improvement of surface flatness can improve the mechanical properties of the additive forming parts.First,the single-channel additive large width-height ratio process test of stainless steel and high-nitrogen steel was carried out.Determine the best thinnest parameters for stainless steel and high-nitrogen steel.The influence of process parameters on weld bead height was explored.Select two sets of process parameters corresponding with different width-height ratio,exploring the effects of different lap joints and additive paths on surface flatness,and determine the best overlap ratio is 60%.When the width-height ratio?is 17.6,the surface flatness of the formed part is better than the surface flatness when?is 7.1.This shows that the smaller the weld bead height,the greater the width-height ratio,the better the surface flatness of the deposit layer under the plasma large width-height ratio process.That is to say,reducing the weld bead height and increasing width-height ratio can improve the surface smoothness of the deposit layer of high-nitrogen steel to some extent;and the surface flatness under the layered orthogonal forming path is better than the surface flatness of the forming parts under the layer stacking path.Further study on the variation of microstructure and properties of high-nitrogen steel additive under different width-height ratio.It is found that when the overlap ratio is 60%,the tensile strength and impact toughness of the vertical weld and the parallel weld were at the optimum values.Among them,the tensile strength of the vertical weld is 1180 MPa,the impact toughness is 50.95 J/cm~2,the tensile strength of the parallel weld is 1160 MPa and the impact toughness is 56.58 J/cm~2.When?=17.6,the corresponding tensile strength and impact toughness are higher than?=7.1,and the variation range is obvious.It shows that while increasing the width-height ratio and improving the surface flatness,the mechanical properties of the formed part can be significantly improved.In the layered orthogonal path,when the width-height ratio?=17.6,the tensile strength in the horizontal and vertical directions is increased by 3.4%,compared with the layer stacking,reaching 1220 MPa.When?=7.1,the tensile strength in the horizontal and vertical directions is slightly improved,and the variation is small.It is indicated that the different forming paths have a greater influence on the tensile strength of the formed parts with greater width-height ratio,and the impact on the tensile strength of the formed parts with smaller width-height ratio.And the tensile strength in the horizontal and vertical directions is improved.When?=17.6,the impact toughness of the front of high nitrogen steel forming parts is 29.3%higher than that of?=7.1,reaching 69.56 J/cm~2.Finally determine the optimal layered overlap structure and the proportion of the different layer thicknesses ratio.The test found that when the layer thickness of the interwoven layer single-layer soft material is sufficiently small,the stainless steel adopts a layer-by-layer interweaving structure.The tensile strength of the formed parts at three ratios is close to that of pure high-nitrogen steel,and the impact toughness is higher than that of pure high-nitrogen steel,which is slightly lower than pure stainless steel.It shows that the designed structure and layer thickness ratio improve the impact toughness strength of pure high nitrogen steel to some extent.In general,when the layer thickness ratio is 3:1,the tensile strength and flexural strength are slightly less than pure high-nitrogen steel,and the impact toughness is much higher than that of pure high-nitrogen steel,which is slightly smaller than pure stainless steel.Among them,the tensile strength is 1100 MPa,the flexural strength is2723.7 MPa,the front impact toughness is 178.16 J/cm~2,and the side impact toughness is167.76 J/cm~2.