Shape Control Process Of 316L Stainless Steel With MIG Arc Additive

MIG wire and arc additive manufacturing(mig-waam)has the outstanding advantages of low cost and high efficiency compared with high energy beam additive manufacturing,which shows obvious advantages in rapid prototyping of large size and complex structures.Waam is a layer by layer deposition process from line to surface and body.The deposition process is sensitive to concave and convex defects,which affects the stability of forming process.Therefore,it is necessary to design deposition parameters and select main control parameters from the perspective of process characteristics,forming and forming.In this paper,pulsed MIG welding was used as heat source and 316 L stainless steel wire with diameter of 1.2mm was used as raw material to study the forming process of mig-waam technology.The influence of key process parameters on the single-layer single pass morphology quality was investigated.The results show that the substrate temperature has obvious influence on the single-layer single-pass arcing end,and increasing the substrate temperature can significantly improve the influence on the arc starting end during forming;the layer width is positively related to the change of forming current,and the layer height decreases temporarily with the increase of forming current;the layer width and layer height are closely related to the forming current The change of shape velocity is negative correlation.The regression model between the process parameters and the geometric size of the forming part was established by response surface design method.The influence of stacking current and stacking speed on the effective wall width and layer height was obtained.The regression equation was well fitted by variance analysis and experimental verification.The model can predict the forming size under the process parameters and obtain the deposition parameters under the specific deposition size 。 On the basis of the above experiments,the influence of forming parameters on the surface undulation and cladding efficiency of the formed parts was investigated.The microstructure of single pass,single layer and multi-layer single pass was analyzed.When the forming current and forming speed are constant,the ferrite size will increase obviously with the increase of the interlayer temperature,and part of the lath ferrite will be transformed into skeletal ferrite;under the condition of the constant interlayer temperature,the microstructure of the formed parts will change with the change of forming current and forming speed.The fundamental reason lies in thechange of cooling rate caused by the change of process parameters With the decrease of cooling rate,lath ferrite will be transformed into skeletal ferrite.The relationship between process parameters and mechanical properties is studied,which provides a basis for the design of deposition parameters.The results show that the change of interlaminar temperature has little effect on the hardness of the middle stable transition stage,but the tensile strength decreases with the increase of interlayer temperature;the tensile strength decreases gradually with the increase of stacking current;the change of velocity has little effect on the tensile strength,but the tensile strength in vertical direction is greater than that in horizontal direction under different process parameters It is anisotropic.