IN718の極低温破壊機構に及ぼす影響因子

概要

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An elastic-plastic fracture toughness test was conducted at 4 K and 290 K to investigate the factors influencing fracture behavior of IN 718. First, the effect of grain size on the fracture toughness and tearing modulus was clarified. It was found that at 4 K the pop-in behavior was dominant in both coarse- and fine-grained materials. However, the fracture surface examination showed that ductile dimple formation prevailed in the coarse-grained meterial while alternating narrow dimple bands and cleavage facets were observed in the fine-grained material. Results showed that fracture toughness increases with increasing grain size. Second, IN 718 with few inclusions was used to clarify the effect of cleanliness. It was revealed that at 4 K the fracture toughness was comparatively increased due to the presence of few inclusions while the tearing modulus was decreased since the presence of many fine brittle carbides contributed to sudden crack growth.
一般社団法人日本機械学会の論文
1995-03-25