鋼の高温における引張諸性質の変形速度依存性
鉄鋼材料の高速衝撃引張試験に関する研究-II
1962 年 48 巻 1 号 p. 28-34
詳細
1962 年 48 巻 1 号 p. 28-34
This paper describes of the influences of deformation rate of wide range on the tensile impact properties of several steels by using a high-speed impact-tensile testing machine with a large rotary disk. The deformation rate was varied from static region to 80m/s, and the testing temperature from room temperature to 800°C. The results obtained were summarized as follows:
(1) Blue brittleness was observed clearly in mild steel and two alloy steels, and temperature range of blue brittleness shifted to higher temperature with increasing rate of deformation. This shift was conspiquous up to a speed of deformation of 10m/s, but was decreased beyond this speed. Moreover, at the speed of 40m/s the blue brittleness temperature was decreased on the contrary.
(2) The similar dependence on deformation rate was also made clear, with regard to the brittleness of 18-8 stainless steel which was due to the effect similar to that causing blue brittleness as well as the brittleness of pure copper at elevated temperature.
(3) At higher temperature over 600°C, the critical impact velocity was not observed so distinctly as obtained at room temperature. Tensile strength was lowered with a larger scattering as the deformation rate was increased, while, correspondingly, the value of elongation or reduction of area showed tendency to be rather larger. This phenomenon, named by the authors as “high-rate deformation softening”, was discussed in relation to the loadtime curves observed experimentally.
