SUS304銅の高温低サイクル疲労強度に及ぼすひずみ波形効果

概要

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The loe cycle fatigue tests were conducted on Type 304 stainless steel at 500℃ and 550℃,where dynamic strain aging easily occurs,and the sffect of strain waveform on the low cycle fatigue life was studied.As the strain waveforms,the triangular,siow-fast and fast-siow waveforms under the total strain range Δε_t=1.0 or 0.5% with a tension going strain rate of 1 to 0.001%/s and compression going strain rate of 1 to 0.001%/s,were used. The results of the present study are summarized as follows ; (1) The negative strain rate dependence due to dynamic strain aging was observed at the strain rate more than about 0.01%/s to 0.005%/s under both strain range Δε_t=1% and 0.5% at 550℃. A similar tendency was also observed hr the thermal aged materiai (650, 700℃×500-3000 h, Δε_t=1%), although hardening due to dynamic aging was low. (2) The low cycle fatigue life was approximately dominated by the tension going strain rate. Tbe increasing of intergranular fracture with decreasing the strain rate was caused by the creep effect in tension going period rather than the dynamic strain aging. (3) The thermal aged material (700℃×3000 h) had a fonger fatigue life than the solution heat treated material, because the stress in tension was reduced due to the decreased dynamic strain aging.
社団法人日本材料学会の論文
1990-07-15