Al合金7075-T6押出し材の疲労き裂伝ぱ挙動に及ぼす湿度の影響

Translated title of the contribution: Effect of Humidity on Growth Behavior of a Fatigue Crack of 7075-T6 Extruded Al Alloy

仮屋 孝二, 前田 季輝, 皮籠石 紀雄, 陳 強, 中村 祐三, 森野 数博

Research output: Contribution to journalArticle

Abstract

In order to investigate the effects of humidity change and loading frequency on growth behavior of a fatigue crack of an extruded bar of an age-hardened Al alloy 7075-T6, rotating bending fatigue tests were carried out in relative humidity of 25% and 85% at frequencies of 50Hz and 6Hz. At 50Hz, macroscopic appearances of fractures were a shear mode at high stress levels in high humidity, though those were a tensile mode in other conditions of humidity and stress levels. The crack growth rate was accelerated by high humidity. By changing humidity, both of the growth rate and the growth mode of a crack were immediately changed to those corresponding to the changed humidity. That is, the growth behavior and fatigue life under humidity change may be estimated by those in constant humidity. Fatigue life in high humidity at 6Hz was longer than that at 50Hz in spite of accelerations of both of the crack initiation and its growth rate in the early growth process in high humidity at both frequency, though there was no or little influence of frequency on fatigue life in low humidity. Moreover, the crack propagated in the tensile mode even at high stress levels where the shear mode crack propagated at 50Hz. These results were explained by the effect of hydrogen on the crack growth behavior.
Original languageJapanese
Pages (from-to)712-718
Number of pages7
JournalZairyo/Journal of the Society of Materials Science, Japan
Volume61
Issue number8
DOIs
Publication statusPublished - 2012

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humidity
Atmospheric humidity
cracks
fatigue life
Fatigue of materials
Cracks
Fatigue cracks
Crack propagation
bending fatigue
shear
fatigue tests
crack initiation
Crack initiation
Hydrogen
hydrogen

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Al合金7075-T6押出し材の疲労き裂伝ぱ挙動に及ぼす湿度の影響. / 仮屋孝二; 前田季輝; 皮籠石紀雄; 陳強; 中村祐三; 森野数博.

In: Zairyo/Journal of the Society of Materials Science, Japan, Vol. 61, No. 8, 2012, p. 712-718.

Research output: Contribution to journalArticle

仮屋孝二 ; 前田季輝 ; 皮籠石紀雄 ; 陳強 ; 中村祐三 ; 森野数博. / Al合金7075-T6押出し材の疲労き裂伝ぱ挙動に及ぼす湿度の影響. In: Zairyo/Journal of the Society of Materials Science, Japan. 2012 ; Vol. 61, No. 8. pp. 712-718.
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abstract = "In order to investigate the effects of humidity change and loading frequency on growth behavior of a fatigue crack of an extruded bar of an age-hardened Al alloy 7075-T6, rotating bending fatigue tests were carried out in relative humidity of 25{\%} and 85{\%} at frequencies of 50Hz and 6Hz. At 50Hz, macroscopic appearances of fractures were a shear mode at high stress levels in high humidity, though those were a tensile mode in other conditions of humidity and stress levels. The crack growth rate was accelerated by high humidity. By changing humidity, both of the growth rate and the growth mode of a crack were immediately changed to those corresponding to the changed humidity. That is, the growth behavior and fatigue life under humidity change may be estimated by those in constant humidity. Fatigue life in high humidity at 6Hz was longer than that at 50Hz in spite of accelerations of both of the crack initiation and its growth rate in the early growth process in high humidity at both frequency, though there was no or little influence of frequency on fatigue life in low humidity. Moreover, the crack propagated in the tensile mode even at high stress levels where the shear mode crack propagated at 50Hz. These results were explained by the effect of hydrogen on the crack growth behavior.",
author = "孝二 仮屋 and 季輝 前田 and 紀雄 皮籠石 and 強 陳 and 祐三 中村 and 数博 森野",
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AU - 仮屋, 孝二

AU - 前田, 季輝

AU - 皮籠石, 紀雄

AU - 陳, 強

AU - 中村, 祐三

AU - 森野, 数博

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N2 - In order to investigate the effects of humidity change and loading frequency on growth behavior of a fatigue crack of an extruded bar of an age-hardened Al alloy 7075-T6, rotating bending fatigue tests were carried out in relative humidity of 25% and 85% at frequencies of 50Hz and 6Hz. At 50Hz, macroscopic appearances of fractures were a shear mode at high stress levels in high humidity, though those were a tensile mode in other conditions of humidity and stress levels. The crack growth rate was accelerated by high humidity. By changing humidity, both of the growth rate and the growth mode of a crack were immediately changed to those corresponding to the changed humidity. That is, the growth behavior and fatigue life under humidity change may be estimated by those in constant humidity. Fatigue life in high humidity at 6Hz was longer than that at 50Hz in spite of accelerations of both of the crack initiation and its growth rate in the early growth process in high humidity at both frequency, though there was no or little influence of frequency on fatigue life in low humidity. Moreover, the crack propagated in the tensile mode even at high stress levels where the shear mode crack propagated at 50Hz. These results were explained by the effect of hydrogen on the crack growth behavior.

AB - In order to investigate the effects of humidity change and loading frequency on growth behavior of a fatigue crack of an extruded bar of an age-hardened Al alloy 7075-T6, rotating bending fatigue tests were carried out in relative humidity of 25% and 85% at frequencies of 50Hz and 6Hz. At 50Hz, macroscopic appearances of fractures were a shear mode at high stress levels in high humidity, though those were a tensile mode in other conditions of humidity and stress levels. The crack growth rate was accelerated by high humidity. By changing humidity, both of the growth rate and the growth mode of a crack were immediately changed to those corresponding to the changed humidity. That is, the growth behavior and fatigue life under humidity change may be estimated by those in constant humidity. Fatigue life in high humidity at 6Hz was longer than that at 50Hz in spite of accelerations of both of the crack initiation and its growth rate in the early growth process in high humidity at both frequency, though there was no or little influence of frequency on fatigue life in low humidity. Moreover, the crack propagated in the tensile mode even at high stress levels where the shear mode crack propagated at 50Hz. These results were explained by the effect of hydrogen on the crack growth behavior.

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DO - 10.2472/jsms.61.712

M3 - 記事

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JO - Zairyo/Journal of the Society of Materials Science, Japan

JF - Zairyo/Journal of the Society of Materials Science, Japan

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