高温におけるSCM 435 焼入れ焼もどし材の微小き裂発生及び進展挙動に及ぼす繰返しひずみ時効の影響

概要

論文の詳細を見る
Quantitative observations have been made on the microcracks or small surface cracks in rotating bending fatigue tests of smooth specimens of a quenched and tempered Cr-Mo steel (SCM435) at temperatures up to 450℃. The total life reached a maximum value at about 350℃ as a consequence of the inhibition of microcrack nucleation and the arrest of propagation due to cyclic strain aging. The length of microcrack nucleated was about 10μm. In the crack length range of about 300μm to 10mm, the da/dN-ΔK relations held up to 450℃. With the propagation stage from 10μm to 300μm, the relations of the linear fracture mechanics as the above mentioned were not always applicable. The most contribution of cyclic strain aging was performed in the propagation stage up to 300μm. The ratio of the number of cycles in this stage to the total life was about 85%.
1985-04-25