Research On Plasma Additive Manufacturing Process For High Nitrogen Steel-stainless Steel Using Filamentous Wire

In order to solve the problems of metal heterogeneous heterogeneity and integral forming of components in arc additive manufacturing,the research on plasma arc additive manufacturing process and forming limit size of high nitrogen steel-stainless steel filaments was carried out.mm and 0.6 mm wire,conventional wire diameters are 1.2 mm and 1.0 mm.First,the high-speed imaging equipment was used to study the stability of filament plasma arc additive forming,and the suitable wire end height was 0.5 mm to 1.25 mm,and the optimal wire feeding direction was forward wire feeding;and high nitrogen steel was explored.The characteristics of droplet transfer of filament plasma arc additive,the results show that the filament plasma arc additive has a higher droplet transition frequency and a smaller droplet size than the conventional wire;The transition frequency of wire droplets is about 8 times of the transition frequency of 1.2 mm diameter wire,and the droplet volume is1/8.Then explored the process parameter window of high-nitrogen steel filament plasma arc forming and the influence of the process parameters on the forming size,and obtained an ultra-thin deposition channel with a layer height of 0.17 mm,a melt width of 9.8 mm,and a melt width of 2.52 mm,a very narrow cladding channel with a layer height of 0.78 mm.The design dimensions of plasma arc additive for high nitrogen steel and stainless steel filament were modeled by Design-Expert software,and the mathematical model between layer height and melting width and process parameters was obtained.The narrowest limit size of filament single-layer multi-layered straight wall additive was studied.The mathematical model was used to calculate the layer-by-layer change rate of additive,to control the width change of the straight-walled additive to obtain a narrower straight wall.The narrowest straight wall body was added using stainless steel wire with a diameter of 0.6 mm,to obtain a straight wall body with an average width of 3.40 mm.The interweaving test was conducted;inserting an extremely short stainless steel section into a high-nitrogen steel rail,under continuous arc forming mode using filaments and conventional diameter wire materials;And between the high-nitrogen steel rails,a positive narrow stainless steel cladding channel was used.Interlaced forming test.The results show that the conventional interlaced form of the two-dimensional interlaced additive cannot be formed well.However,the use of filaments for interlaced interstitial additive experiments shows that the high-nitrogen steel-stainless steel joint can obtain a good surface morphology and weld.The overall shape of the track is good;in the interweave method of the road,a 5mm section of stainless steel is inserted into the multi-layer and multi-pass additive in the high nitrogen steel track.The tensile strength along the stacking direction is 795 MPa,the elongation after breaking is 32.1%,and the impact toughness is 71.3 J/cm~2.Using filaments for inter-channel interlaced additive experiments,when a gap of 1 mm is reserved between the high-nitrogen steels on both sides,the narrowest stainless steel deposited channel width is 4.2mm,and the high-nitrogen steel-stainless steel interweaving area is well formed.Obvious defects;tensile strength along the stacking direction is 840 MPa,post-break elongation is36.7%,and impact toughness in the vertical stacking direction is 88 J/cm~2.