The Simulation And Coating Studying Of Stainless Steel Powder Hot Isostatic Pressing

Compared with the traditional mechanical pressure forming technology, hot isostatic pressing technology can produce performance uniformity and high compactness of component. This technology open up a new path for producing acid resistance, wear resistance, and high temperature resistant of mechanical components. So this article uses finite element simulation method to simulate the hot isostatic pressing forming process of stainless steel powder.This article adopts the Shima yield criterion to describe the powder material constitutive relation, and the Von-Mises yield criterion to describe the coating material constitutive relation. Using the thermal-mechanical coupling model of finite element simulation software Marc builds the model of the powder hot isostatic pressing forming process, and then determine the parameters of the model of stainless steel powder. I simulate multiple sets of model under different temperature and pressure. Simulation results show that the average relative density increases with the increase in the temperature and the holding pressure. Combined with the actual conditions and material properties, I optimize the process parameters, and then gain the best technological parameter that is temperature 1050℃ and pressure 140MPa. Under the optimum process conditions, the relative density of the cylinder samples relative is up to 0.9878. Owing to structure symmetry of the cylinder sample, the powder body shrinks under the pressure and temperature, but it does not uniformly shrink. The center parts of the top have the maximum axial shrinkage, and the middle parts have the maximum radial shrinkage. Edges parts have minimum overall shrinkage.The material selection and structure design directly affect the implementation of forming process, so we should choose appropriate coating materials and reasonable structure. According to the scope of coating thickness, I design the 1.0mm,2.0mm, 3.0mm,4.0mm and 5.0mm coating thickness. Coating material is 304 stainless steel Using different coating thickness, I simulate heat isostatic pressing forming process of the powder under pressure 140MPa and temperature 1050℃. Under different coating thickness, the powder body shrinkage is less than 13.0%. For package edge, we should design to rounded corners, and avoid edges and corners as far as possible. We should reduce resistance of deformation, and promote uniform of radial shrinkage and distribution of relative density.Based on optimized process conditions and coating structure of simple columnar test samples, and combined with the shape of the blisk, I design the capsules of the blisk. Different with the simple columnar test samples, the blisk structure is complex, especially the blade is thin. We should add a rigid core blocks to ensure the shape of the blade. Because of core inlay pieces and the settings of boundary conditions in the special position, the blisk is uneven contraction. However contraction basic lines keep straight. Blade still can maintain its original shape, which is convenient to mechanical processing. Near the core inlay pieces, inlay pieces hinder the contraction of the powder body, and reduce the relative density of powder body. Although the relative density of some parts has been reached 100%, the distribution of relative density and the size of the powder body have not reached the ideal consequence. I need to further modify coating structure to improve the distribution of relative density.In this paper, from simple to complex, and from process conditions to the coating structure, I detailed analyze the hot isostatic pressing forming process of the powder body. For complex parts manufacture process, it provides good guidance.