変態塑性変形を考慮した大型鍛鋼熱処理時の残留応力

冷却速度の影響

抄録

The subject of this paper is to calculate the residual stress occurred during heat treatments of the large forged steel using Finite Element Method (FEM). The analysis was carried out using a cylindrical FEM model of ASTM-A-470 used in rotor shafts for power stations. First, a heat transfer analysis was performed to obtain a temperature history, which is used to calculate material properties at varied temperatures. Then, using the temperature history, structure analyses were conducted considering both the creep deformation and the transformation plasticity. The residual stresses calculated by the structure analysis were compared with the value measured by experiments. As a result, the calculated residual stresses have the same tendency as the measured residual stresses when both the creep and transformation plasticity are considered. Therefore, the importance of both the creep and transformation plasticity for the structural analysis of the heat treatment of the large forged steels was confirmed. In addition, the effect of the cooling rate to the residual stress was also discussed.