アルミニウム合金の安定破壊機構のフラクトグラフィ的検討

概要

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The total volume fraction of second phase particles, f_v, has been well related to the plane-strain fracture toughness, K_<Ic> of the material. From this point of view, the influence of the distance from a pre-crack tip to an inclusion on both the stable crack initiation mechanism and the critical stretched zone width, SZW_c, as a measure of localized fracture toughness along the crack front, was investigated utilizing electron fractography. The materials used were five aluminum alloys, 5083-O. 2017-T3, 2024-T3, 7075-T6, and 7N0l-T6. The results obtained are summarized as follows : (1) For the aluminum alloys used, the following relationships between the sub-critical stretched zone width, SZW and J-integral do not stand ; SZW=C_1J/E (1) SZW=J/C_2σ_<fs> (2) where E is Young's modulus and σ_<fs> is flow stress. However, for the intermediate strength aluminum alloys (2017, 2024, 7N01), both equations can stand apparently. (2) According to the fractographic observation, there exist three types of stable crack initiation mechanisms. (3) The variation of localized fracture toughness, SZW_c, along the crack front arises due to the variation of the distance from the pre-crack tip to the inclusion, which causes the change of stable crack initiation mechanisms.
社団法人日本材料学会の論文
1982-05-15