Study On Arc Addition Technology For High Nitrogen Steel-316L Stainless Steel Double-Wire PMIG Arc Welding

Based on double-wire PMIG welding robots,this research project focuses on high nitrogen steel and 316L stainless steel.Analyzing the influence of additive process on forming characteristics,stratum structure and mechanical properties.Inoder to carry out a number of overlapping pile test and additive process parameters screening,followed by arc additive forming process of different materials interlaced structure.Firstly,the effect of protective gas composition and heat input on single-channel deposition,nitrogen content and porosity of high nitrogen steel was studied.Adding a small amount of oxygen in the shielding gas can improve the welding stability,increase the interlayer nitrogen content and reduce the stratospheric porosity.Addition of appropriate amount of nitrogen can reduce the surface porosity and effectively increase the nitrogen content in the interlayer.Excess nitrogen can not increase the interlayer nitrogen content obviously,and lead to instability of the arc and increase of the porosity,The size of the heat input affects the melting time,and the presence of the weld pool decreases the nitrogen content in the channel and increases the stratospheric porosity and pore diameter.Then,the research on the characteristics of single-pass deposition of the two materials was carried out.The process parameters of the two materials were determined.The influence of the parameters of the additive on the macro-geometry of the deposited single-pass was also explored.The single-channel multi-wall straight wall test of high nitrogen steel was carried out to study the influence of interlayer temperature and shielding gas composition on the forming,microstructure and mechanical properties.Starting from the interpass temperature of 50?,the tensile strength of straight-wall tensile specimens increases first and then decreases with the increase of interlayer temperature.With the increase of interlayer temperature,the morphology of the dendrite began to become coarse and its growth direction tended to be the same on the microstructure.The microstructure of the fracture changed as follows:the size and number of the second phase particles increased,Proportion decreased,porosity,inclusions increased defects.Adding a certain amount of N2 to the protective gas increases the tensile strength and toughness of the additive,while excess N2 is detrimental to performance.With the increase of N2 ratio,the ferrite content decreased,the amount of precipitates around dendrites increased,and the stomatal defect rate increased.The microscopic appearance of the fracture showed that the size and number of the second phase particles increased,and the stomatal defect rate increased.The concept of single-section cross-sectional area error E was introduced to optimize the single-section cross-section width and height of the post-processing window as the data background.The arc model with the smallest error and the most stable fluctuation was selected as the ideal deposition cross-section model.From the size and area more than the matching process of screening out the most suitable combination of materials for the different shape of the interlaced structure of the process parameters.The arc section model is substituted into the layer overlap mode,and the ideal path spacing is predicted through theoretical calculations,which is consistent with the actual test results.In the study of multilayer multi-channel interlacing structure,it was found that with the increase of the height,the hardness of the structure with the same material increased first and then decreased and then decreased again at the top of the added material.Because of the fine grain size after a certain degree of hardness in the remelting area has a sudden increase in the law.Under the same composition ratio,different interlaced structures have different ability to absorb impact energy;the higher interlacing structure interlaces,the stronger absorptive capacity to impact energy.Finally,the arc-added biomimetic armor plate test,the use of anti-deformation method to eliminate heat distortion caused by welding substrate,by forming the final plus the positive and negative double-sided on the same substrate 304 to obtain the inscribed circle diameter of 240mm high 60mm Stainless steel composition ratio of 4:1 were interlaced tween twelfth bionic armor plate and conduct a target test.