Evaluation of tensile properties of safety-conscious rolled steels for building structure (SN steels) at high temperature

Rolled steels for general structure (SS steels), which are provided in the Japanese Industrial Standard, are used for support structures in nuclear power plants. They do not have any necessary conditions as welding steels; therefore, alternative steels with good welding properties are required. Rolled steels for building structure (SN steels) are expecting to be candidate steels form their high weldability and toughness. In order to apply SN steels as structural materials, tensile properties must be consolidated, however, tensile data only at room temperature are provided in the Japanese Industrial Standard and those at high temperature are not adequately acquired so far. In this report, comprehensive tensile tests for SN steels were conducted at high temperature and the tensile properties were compiled. Three materials with different origins were prepared for four types of SN steels (SN400B, SN400C, SN490B, and SN490C) and two different plate thickness (40 mm and 100 mm), thus, 240 tensile tests were conducted under the temperature condition from RT to 400degC. The effect of temperature on the yield stress or tensile strength was approximately similar in spite of the differences in the origins, material type, or plate thickness. The effect of strain rate on the tensile properties was small, and the effect of the contents of P and S on the tensile properties was also small. (author)