オーステナイト・ステンレス鋼SUS304B, 316Bの回転曲げ高温疲労現象
1973 年 22 巻 234 号 p. 257-264
詳細
1973 年 22 巻 234 号 p. 257-264
In order to collect experimental data of the fatigue strength of materials, the rotating bending fatigue tests were carried out on two kinds of austenitic stainless steels (Type 304 and 316) at room temperature, 400, 500, 600 and 700°C with the frequency of 7500r.p.m., and their fatigue strength at 108 cycles was obtained.
The conclusions obtained are as follows:
(1) Endurance limits were clearly found in the temperature range from room temperature to 600°C. At 700°C a clear endurance limit seemed to appear below 107 cycles, but the fatigue fracture started to occur after 107 cycles.
(2) The fatigue strength of SUS 316B at 108 cycles is larger than that of SUS 304B at each test temperature.
(3) The ratio of fatigue strength to 0.2% proof stress is 1.2∼1.7 at 400-600°C. This ratio is larger for SUS 316B than for SUS 304B.
(4) The coaxing effect was distinctly observed in the temperature range from 400 to 600°C. At 700°C, it was somewhat observed during the test after 9×105 cycles but it disappeared after 108 cycles.
(5) The above phenomena commonly observed for the two steels are considered to arise from the same origins. They are the strengthening of the material caused by aging during the fatigue test at 400-600°C, and the softening due to overaging after 107 cycles at 700°C.
