Factors Influencing Fracture Mechanism of IN718 at Cryogenic Temperature

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...

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Bibliographic Details
Published inTransactions of the Japan Society of Mechanical Engineers Series A Vol. 61; no. 583; pp. 553 - 560
Main Authors Teramoto, Tokuo, Kayamori, Youichi, Denda, Takeshi
Format Journal Article
LanguageJapanese
Published The Japan Society of Mechanical Engineers 1995
Subjects
Cleanliness
Cleavage Facet
Dimple
Fracture Toughness
Grain Size
IN 718
Inculsion
Metal Carbide
Pop-in
Tearing Modulus
Twinning
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Summary: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.
ISSN:0387-5008
1884-8338
DOI:10.1299/kikaia.61.553