銅の疲労破壊の統計的性質に及ぼす結晶粒大きさの影響 (第2報)

概要

論文の詳細を見る
The apecimens tested were taken from a part of the boiler steel plate. That part of the boiler steel plate was divided into five layers from the convex side of the surface up to the concave side, and they were named No. 1, 2, 3, 4, and 5 layer according to the order. The specimens from No. 1, No. 2 and No. 3 layer were taken in the rolling derection and the specimens from No. 4 and No. 5 were taken in the transverse direction. The ferrite grain size of the outer (No. I and No. 5), the intermediate (No. 2 and No. 4) and central (No. 3) layers were 7・5, 7・0 and 6・5 in term of ASTM grain size number respectively. From the statistical treatment of the test data on the fatigue life obtained on each layer at several different stress levels, the following conclusions were given : (1) The frequency distribution curve of the fatigue life is more positively skewed in finer ferrite grained steel than in coarse ferrite grained steel. The distribution curve approches to the exponential (or logarithmic normal) type distribution in finer grained steel, and appears to become the roughly normal type distribution in coarse grained steel. (2) The larger the scatter of the fatigue life is, the finer the ferrite grain size becomes. These two conclusions may be understood from the standpoint of probability theory. The formor conclusion may be explained as follows : In fine grained steel the probability (rate) of the fatigue crack initiation per cycle tends to saturate with the increase of repeated cycles after a rapid increasing, and in coarse grained steel the rate increases gradually. The latter conclusion can be understood, since the rate of crack initiation may be assumed as the smaller, the finer the grain size is. Hence it appear that the ferrite path is a prevalent factor in the statistical behavior of the fatigue fracture of steel.
1958-07-15

銅の疲労破壊の統計的性質に及ぼす結晶粒大きさの影響 (第2報)

スポンサーリンク

概要

論文 | ランダム

スポンサーリンク