(α+γ)2相ステンレス鋼の疲労挙動

概要

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The effects of austenite (γ) grain size, ageing at 475℃and volume fraction of γ(V_γ) on the fatigue strength and the process of fatigue crack initiation and early propagation have been investigated using (α+γ) two-phase stainless steels with different grain sizes including microduplex structures. The main results obtained are as follows ; (1) Fatigue cracks were initiated within a γ grain and stopped at the α-γ interface at the fatigue limit for all specimens excepting the quenched ones with large volume fraction of γ. This means that non-propagating cracks are formed which have the same length as the γ grain size. (2) The relation between fatigue limit (σ_ω) and T grain size (d_γ) could be expressed as follows for all the steels investigated. σ^m_ω・d_γ=C The value of C in the equation for the steel aged at 475℃ was larger than that for the quenched one. This result indicates that the fatigue limit of the steels can be improved remarkably by grain refinement and ageing at 475℃. (3) The fatigue limit for the specimens aged at 475℃ depends on d_γonly. On the other hand, the fatigue limit for the quenched ones depends on both d_γ and V_γ.
社団法人日本材料学会の論文
1987-02-15