球圧子押込み試験による機械的性質推定法のガスパイプライン鋼管材料への適用

In this study, conventional and advanced methods with instrumented spherical indentation techniques were applied, respectively, to estimate mechanical properties of steels used in gas pipelines. The advanced method has recently been proposed by authors. The instrumented spherical indentation tests were performed three times for each steel to confirm the reproducibility. Meanwhile, the tensile tests were performed for axial and circumferential directions, respectively. Then, the estimated results of the true stress-true strain curve, yield stress and tensile strength were compared with those obtained by tensile test to validate the estimation accuracy in these methods. The results showed that the indentation load-depth curves were reproducibly obtained in each steel. And then, the tensile test results were in good agreement with those estimated by the advanced method rather than the conventional method. Thus, the utility of the advanced method was successfully demonstrated. From the results, it can be expected that the advanced method with the instrumented spherical indentation technique validated in this study become useful as a maintenance technique for gas pipelines and other steel structures.