極厚材の破壊靱性値に及ぼす力学的板厚効果

概要

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In order to develop an estimation method of the fracture toughness in heavy sectioned A533B steel from small size specimen with reduced thickness, the effects of specimen thickness and side groove on fracture toughness have been investigated. An increase in side groove depth clearly lowers the resistance to ductile crack propagation. This is due to the fact that side groove restrains the formation of shear lip. On the other hand, the slow crack growth initiation toughness is independent of side groove depth. In the case of brittle failures, the fracture toughness is nearly constant irrespective of side groove depth. This fact is confirmed by fractographical examination of stretched zone size on fracture surfaces. It is seen from these results that the fracture toughness for full thickness can not be estimated by using the results obtained in small specimens with side groove. A model is proposed to evaluate effect of specimen thickness on fracture toughness in terms of fracture mechanics. Fracture toughness of thick plate is estimated from this model using the fracture toughness values of ordinarily notched small specimens with reduced thickness. The predicted values are in good agreement with experimental results of full thickness specimens.
社団法人日本鉄鋼協会の論文
1983-04-01