鋳鋼材の静的強度および塑性疲労強度に及ぼす鋳造欠陥の影響

概要

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In this paper, effect of casting defect upon plastic fatigue strength and ductile characteristics of cast steel are briefly described. Tensile test of 14φ and 50φ specimen, strain controlled pushpull type plastic fatigue test of 11φ specimen and load controlled, repeat tension type low cycle fatigue test of 50φ specimen were carried out by using sound material and defective one casted from the same melt. Summarizing the test results, it has been presumed that the relationship between strength S (Yield point, Tensile strength) or ductility F (Elongation, Reduction Area, Fracture ductility and Plastic fatigue strength) and casting defect severity D, defined as the ratio of defect area to final sectional area of fractured specimen, are given by the following formulae: S+aD=C_s, F・D^b=C_f here, a, b, C_s, C_f denote constants. On the other hand, it is known that the constants b and C_f relating with ductility depend upon features of fracture surface which is distinguished into ductile type or quasi-cleavage type, the latter is observed occasionally on cast steel specimen of large size.
財団法人日本海事協会の論文