2017 年 103 巻 9 号 p. 539-548
In this study, Cu-added ferritic stainless steel sheets were investigated to understand the influences of Cu contents on the high-temperature strength during the high-temperature deformation. High-temperature proof stress at 700~900°C was improved greatly by addition of more than 1% of Cu. In the case of static aging at 900°C, the rod-shaped ε-Cu particles satisfied the K-S orientation relationship with the α matrix, but spherical-shaped ε-Cu particles without specific orientation relationship started appearing during the tensile deformation at 900°C. Similarly, the spherical-shaped and fine ε-Cu particles were observed during the thermal fatigue process in the temperature range from 200°C to 700°C with a 50% restriction ratio. During the observation using the high-temperature in-situ TEM straining, it was clarified that the ε-Cu particles were divided by dislocation shearing and parts of them were found dissolved. According to the LSW theory, it was suggested that the microstructure with fine and spherical-shaped ε-Cu particles was formed by the repetition of dissolution and precipitation during the high-temperature deformation.
