計装化した高温押込み試験法による耐熱材料の弾塑性特性評価

抄録

Steam leak accidents occur frequently at weld zone involved in pipes in aged thermal power plants. It is known that the weld zone has heterogeneous microstructure and causes cracking due to thermal stress distribution. Therefore, the material property associated with such a microstructure must be clarified to evaluate precisely crack initiation. Indentation test method is an effective technique for measuring the localized material property. Thus, our group has been established evaluation scheme of the material property by the indentation test. However, the evaluation scheme does not take into account the influence of the indentation rate. In this study, instrumented high-temperature indentation test machine, which can control the indentation load speed by an electric actuator, was developed. Using this machine, the high temperature indentation test was conducted to estimate the yield stress of a heat-resistance alloy Ka-SUS410J3. In addition, the influence of indentation rate on the yield stress was investigated. As the results, it was confirmed that the yield stress was significantly influenced by the indentation rate and the yield stress can be appropriately estimated within the indentation rate of 0.2 - 0.5 mm/min in comparison with a tensile test.