Investigation On Improvement Of Properties Of An Austenitic Stainless Steel By Equal Channel Angular Pressing

Austenitic stainless steel is the most widely used in stainless steel, the production and consumption accounted for70%of the total output of stainless steel. Austenitic stainless steel has more excellent corrosion resistance in a variety of corrosion medium, and good comprehensive mechanical properties, technology, and welding. Obtain different deformation process of the rolling and et al, to get required performance in industrial application of austenitic stainless steel. We can get severe plastic deformation by Equal channel angular pressing (ECAP) process under the condition of not change the shape of metal or alloy, improve the structure and the properties of the metal or alloy.This thesis chooses316stainless-steel which was universal application of austenitic stainless-steel, obtain severe plastic deformation through ECAP process. The parameters of Equal channel angular pressing, such as:insideΦ=135°, outsideΨ=45°, ε=0.45every time, Be extrusion path,320℃. Study tensile strength, micro hardness, and elongation of316stainless-steel during the process of ECAP deformation for different times, changes of corrosion resistance analyzed by anodic polarization. At the same time, using Confocal Laser Scanning Microscope, Scanning Electron Microscope (SEM), X-ray Diffraction and Electron Backscatter Diffraction (EBSD), do research of change of microstructure in316stainless-steel during the process of ECAP deformation, determine the phase change, the fracture mechanism and corrosion resistance, etc. And study the deformation mechanism, strengthening mechanism, corrosion mechanism of316stainless-steel.Small angle grain boundary developing in316stainless-steel by ECAP deformation times, sub grain boundary occurred delivery by crystal slip and twins inside grain, and effects of crushed grain with increasing deformation, XRD analysis results show that the organization for a single austenite after deformation.316stainless-steel deformation after8times ECAP with Be path, fine uniform organization, grain size reduced to50%of the solid solution treatment, tensile strength and yield strength increases, micro-hardness increased almost3times, elongation rate fell sharply, plastic going bad, machining hardening.The tensile fracture of shear lips area increases gradually with the increase of ECAP deformation times, fiber area reduction. With the development of deformation times the toughness litter size going smaller, the shallow depth, the ductile fracture is from gradual shift into brittle fracture. The number and density of stretching nest in Shear lips area also going down with the increasing of deformation and dwindling.316stainless steel extrusion different ways of anode polarization analysis, corrosion potential increased from-0.104V to8times-0.032V, the corrosion current density decreased rapidly, the corrosion of orientation decreased, corrosion resistance increased, with deformation times, the corrosion surface more uniformity.