高湿度下におけるAl合金2017の疲労特性に及ぼす微視組織の影響

Translated title of the contribution: Effect of Microstructure on Fatigue Properties of Al Alloy 2017 in High Humidity

皮籠石 紀雄, 東 晃広, 陳 強, 中村 祐三, 森野 数博

Research output: Contribution to journalArticle

Abstract

In order to investigate effects of a texture and a slip characteristic on fatigue properties of Al alloys in high humidity, rotating bending fatigue tests were carried out using plain specimens of an extruded bar and a drawn one of age-hardened Al alloy 2017-T4 and an Al alloy annealed the extruded one in relative humidity of 25% and 85%. The extruded Al alloy and the annealed one had a marked texture of a (111) plane at the cross section of each bar, but a specified orientation was not observed in the drawn one. In addition, the aged-hardened Al alloys show a planar slip property and the annealed alloy shows a wavy one. In the all Al alloys, the obvious retardation of a small crack growth due to blocking effect of a grain boundary was observed in low humidity, though the retardation disappeared in high humidity. Moreover the acceleration of a crack growth was yielded due to the change in growth mechanism of a crack from a tensile mode in low humidity to a shear mode at high stress levels in high humidity in the extruded alloy, though the effect of humidity on the growth mechanism was very small in the drawn Al alloy and the annealed one. In the extruded Al alloy, the fracture surface yielded by the shear mode crack in high humidity was occupied by many slip planes and voids and was a (100) plane, though the fracture surface formed by the growth of the tensile mode crack in low humidity was covered with striations. In the drawn and annealed Al alloys, fracture surfaces were mainly occupied by striations irrespective of humidity and stress levels.
Translated title of the contributionEffect of Microstructure on Fatigue Properties of Al Alloy 2017 in High Humidity
Original languageJapanese
Pages (from-to)556-563
Number of pages8
JournalZairyo/Journal of the Society of Materials Science, Japan
Volume61
Issue number6
DOIs
Publication statusPublished - 2012

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