SUS 304の軸力疲労特性に及ぼすひずみ時効および過大応力の影響

抄録

Axial cyclic tension-compression fatigue test has been performed about the typical austenitic stainless steel (SUS 304) using a servo-controlled electro-hydraulic fatigue tester. The main object of this study is to investigate the effect of strain aging and overstress on fatigue property of SUS 304, which is applied just after fatigue micro-crack initiation. The main results obtained in this study are summarized as follows : (1) The effect of strain aging on fatigue property which has not been observed in high cycle rotating bending fatigue test, is obviously recognized in low cycle axial compression-tension test. (2) The fatigue life (σ_a=300MPa) is enhanced 211.1 times by the combination of overstress and aging treatment. The reason concerning in this outstanding effect is that, strain aging does play a much more significant role for improving the fatigue strength besides the strain hardening and austenite-martensite transformation caused by overstress. (3) Non-propagating fatigue micro-crack is observed in the specimen, which has been suffered under the stress amplitude of fatigue limit by 1×10⁷ cycles, with combining overstress (525MPa, 50 sec) with aging treatment (350°C×2hrs).