S15C低温焼入れ時効材のコーキシング効果と微視的き裂の関係

概要

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In order to clarify the coaxing process of aged materials, rotating bending fatigue tests were carried out on the 0.15℃ steel aged after quenching at low temperature under various aging conditions and optical microscopic observations were made successively during the coaxing process by using the plastic replica method. The main results obtained are as follows : (1) The knee-point in the S-N curve coincides nearly with the point where a micro-crack stops propagating. (2) As the aging power gets greater, the knee-point on the S-N curve moves toward the lower number of stress cycles and the length of non-propagating cracks becomes longer. (3) When the fatigue limit is raised by coaxing effect, the non-propagating micro-crack formed under the first stress level propagate in some degree and then stops by each stepping-up of stress level. (4) As the aging power gets greater, both the rate of increase in fatigue limit by coaxing effect and the increase in crack length becomes greater. (5) The coaxing effect of an aged material is more remarkable in the case where the non-propagating micro-crack under the first stress level is short.
社団法人日本材料学会の論文
1980-02-15