Effects of Hydrogen in Aluminium, Magnesium, Copper, and Their Alloys

Talbot, David E.J.

doi:10.1179/095066075790136871

Cited by 38 publications

(28 citation statements)

References 11 publications

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“…4) For a typical amount of hydrogen (0.3 cc/100 g Al), supersaturated hydrogen is trapped at dislocations or interstitial positions around micro pores while with higher hydrogen content, they are trapped predominantly by solute atoms or at interstitial positions. 4) This contradicts the conventional theory 1,3,5) which states that vacancies must be present for micro pore formation.…”

Section: Introductioncontrasting

confidence: 45%

Four-Dimensional Annihilation Behaviors of Micro Pores during Surface Cold Working

Toda

Yamaguchi²,

Nakazawa

et al. 2010

Mater. Trans.

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The annihilation behavior of micro pores in an aluminum alloy casting during surface cold working was continuously observed using the synchrotron radiation microtomography. To analyze micro pore annihilation behavior, the displacement of artificially dispersed particles was measured and thereby local strain distributions were mapped in high-density. A peening treatment annihilated most of the micro pores with a diameter of over 10 mm in the upper part of the specimen that could initiate fatigue cracks. The annihilation behavior of the micro pores could be understood as a function of effective strain locally accumulated around them, and not as a function of local hydrostatic strain. The effective strain varied significantly, with some large pores remaining where local effective plastic strain was relatively low. The complete annihilation of large pores in the surface layer suggests that the application of sufficiently long surface cold working is effective in improving the high-cycle fatigue properties.

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Section: Introductioncontrasting

confidence: 45%

Four-Dimensional Annihilation Behaviors of Micro Pores during Surface Cold Working

Toda

Yamaguchi²,

Nakazawa

et al. 2010

Mater. Trans.

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show abstract

“…It has been reported that secondary porosity in aluminum alloys does not close through extensive deformation by hot and cold rolling. 4) Direct observation of healing/reopening during plastic working and subsequent heat treatments also revealed the morphologically variable behaviors of micropores during 60% compression. 15) For example, some micropores remained even after 60% compression, while others were apparently annihilated within the limited resolution of the tomography setup used.…”

Section: Discussionmentioning

confidence: 99%

“…5) For example, it has been reported that tensile strength decreases rapidly if porosity increases up to 0:5 $ 1%. 4) It seems that the mechanisms for such rapid decrease with a limited porosity have not been fully clarified in the literature. Since the ordinary ductile fracture process consists of void initiation, growth and coalescence, it can be readily supposed that the high-density micropores make some contributions to ductile fracture.…”

Section: Introductionmentioning

confidence: 99%

“…2) Porosity is one of the common production defects observed in both wrought and cast aluminum alloys. 1,3) It has been clarified that percentage porosity depend on the hydrogen content in aluminum alloy, 4,5) strongly suggesting that micropores in aluminum alloys are filled with molecular hydrogen. Synchrotron X-ray microtomography has been applied to the observations of high-density micropores, [6][7][8][9][10][11][12] because this technique is especially effective for micropore observation, since micropores are easily filled with abrasive powders during sample preparation processes for observation, such as cutting and polishing.…”

Section: Introductionmentioning

confidence: 99%

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Roles of Pre-Existing Hydrogen Micropores on Ductile Fracture

et al. 2009

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Synchrotron X-ray microtomography was used to observe hydrogen micropores. Competitive growth between pre-existing high-density micropores and voids originating from damage during loading was observed in an aluminum alloy during a tensile test. Extensive and premature growth of pre-existing hydrogen micropores has been observed during tension, while the ordinary damage initiation increased rapidly more later. According to the estimation on the areal fraction of dimple patterns originating from the pre-existing hydrogen micropores, it has been concluded that the hydrogen micropores more or less make contributions to ordinary ductile fracture.

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“…13) It is also known that such hydrogen pores do not close through subsequent extensive plastic deformation in the production processes involving wrought aluminum alloys. 1,4) Hydrogen pores are therefore associated with mechanical properties even in wrought aluminum alloys.…”

Section: Introductionmentioning

confidence: 99%

Effects of Stress Triaxiality on Damage Evolution from Pre-Existing Hydrogen Pores in Aluminum Alloy

et al. 2014

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It has recently been reported that aluminum alloy ductile fracture is dominated by micropore growth, whereas the particle fracture mechanism operates incidentally. The effects of stress triaxiality in front of a notch or crack were here investigated by employing microtomography observations. A fractional dimple pattern area originating in micropores increased with the increase in stress triaxiality on fracture surfaces. This implies that the effects of micropores on mechanical properties are more pronounced in notched and cracked materials.

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Effects of Hydrogen in Aluminium, Magnesium, Copper, and Their Alloys

Cited by 38 publications

References 11 publications

Four-Dimensional Annihilation Behaviors of Micro Pores during Surface Cold Working

Four-Dimensional Annihilation Behaviors of Micro Pores during Surface Cold Working

Roles of Pre-Existing Hydrogen Micropores on Ductile Fracture

Effects of Stress Triaxiality on Damage Evolution from Pre-Existing Hydrogen Pores in Aluminum Alloy

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