溶接部の疲労き裂進展挙動について

概要

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Crack growth rate of the second-stage fatigue at weld and neighboring weld were examined for butt joint of structural rolled steel by three-points bending fatigue test. Effect of low temperature (-55℃) on crack growth rate (da/dN) were investigated for weld metal. Results obtained are summarized as follows ; (1) Crack growth rate (do/dN) of weld and near weld are lower than that of base metal and consequently, decreasing ratio of da/dN for low stress intensity factor ΔAK level were larger than that for high ΔK level. (2) Crack growth rate (da/dN) at the parts of 5mm and 10mm from bond line provides less difference. (3) Crack growth rate (da/dN) on the bond line (weld metal) is the lowest, and thus da/dN are 1/7.1 of base metal for ΔK = 18MPa√<m>, and 1/1.6 for ΔK = 40MPa√<m> respectively. (4) Low temperature effect of extending fatigue life is recognized for weld metal as same as for general carbon steel. Crack growth rate (da/dN) at low temperature (-55℃) provides 1/2〜1/2.2 of da/dN at room temperature.
秋田工業高等専門学校の論文
2003-02-28