316Lステンレス鋼薄板材の高温強度特性に及ぼす結晶粒径と板厚の影響

概要

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The mechanical properties of thin-plate and thin-pipe specimens of Type 316L austenitic stain-less steel (thickness t : 0.05 to 1.0 mm, grain size d : 65 to 353 μm) were investigated at room and elevated temperatures. The tests were carried out with tensile tests at room temperature , 573K and 923K, and with creep tests at 923K only. The ultimate tensile strength σ_B and the total elongation et generally decreased with a decreasing value of t/d when the ratio was smaller than the critical value. The critical value of t/d was estimated as 8 to 10 forσ_B and ε_t at room and elevated temperatures in this study. The fracture mode of the specimens was generally ductile fracture with severe local contraction at the smaller value of t/d and at the elevated temperature. The creep rupture time T_r decreased with increasing d and an initial creep stressσ_C, and the steady-state creep rate δ_S increased with increasing d and σ_C of thin-plate specimens. These dependences of T_r and σ_C on d andσ_C were similar to those of bulk specimens, but the value of o. of the thin specimens was very low in comparison with that of the bulk ones because of the weakness when the value of t/d was smaller than critical value.
1989-05-25