Simulation Of Stainless Steel Wheel’s Deformation After Its Heat Treatment Process

As the nuclear main pump stainless steel wheel is of large size and its geometric shape is complicated, it often crazes or its deformation turns to be beyond the limited range after its heat treatment process. And this leads to the stainless steel wheel’s extra heat treatment, mechanical process, or directly being scrapped. These will definitely raise the cost of the product and extend the production cycle. By doing numerical simulation of the stainless steel wheel’s heat treatment process, stress field, strain field, and the distribution of temperature of the wheel during its heat treatment process can be obtained. It can be predicted that possible defect during the forming process of the wheel and the change of dimension after its heat treatment. So, this provides researchers with scientific basis to analyze the technology and optimize the technology.In this article, the technology of heat treatment numerical simulation and its current development are analyzed. Being based on heat treatment software DEFORM, a finite element model of the stainless steel wheel is set up, including the selection of parameter, the choosing of element type, meshing, presetting of boundary conditions and so on, and simulation system of coupling thermal stress and organizational transformation is studied. Based on related stainless steel heat treatment technology, the effect of three different charge temperature 300℃, 400℃, 500℃ and three different warming speed 100℃/h, 125℃/h, 150℃/h on max stress curves during warming process is analyzed. The study shows that when the charge temperature is 400℃ and the warming speed is 125℃/h, the max stress produced in the process of warming is the closest to but not beyond the yield strength of the material under its current temperature. This heat treatment technology ensures its heat treatment result, shortens its heat treatment time to its greatest extent, improves its heat treatment efficiency and at the same time, avoids the appearance of large deformation; the heat treatment method normalization is adopted. During the cooling process, the max stress is 802 MPa, locating in the root of the wheel’s blade, the stress is not beyond the material’s tensile strength 860 MPa, the root of the wheel will not craze.According to the simulated heat treatment technology, temperature field, stress field, and texture changing situation of the wheel’s different locations are analyzed. The analysis method of coupling texture, temperature and stress is used, and the max deformation is 3.9mm, of which the location is the max diameter. And the effect of texture changing on deformation is studied and the result shows both thermal stress and texture changing stress contribute to the deformation of the wheel. The factor of the texture changing can not be ignored.Verification experiment is carried out to verify the simulation result. By comparing the verifying experiment data with the computer simulation data, it is found that they almost agree with each other with the max error being less than 0.5mm. This research is helpful to the choice of heat treatment technologies and the deformation prediction of complicated components.