Langsames Ermüdungsrisswachstum in Aluminium- und Magnesiumgusslegierungen in Raumluft und in Vakuum

Fuchs, U.; Mayer, H.; Tschegg, Stefanie; Zettl, B.; Lipowsky, H.; Stich, A.; Papakyriacou, M.

doi:10.1002/1521-4052(200201)33:1<15::aid-mawe15>3.0.co;2-h

Cited by 7 publications

(2 citation statements)

References 24 publications

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“…The fatigue response of magnesium alloys is considerably sensitive to the testing environment. Several researchers [1,10,13] have shown that long fatigue-crack growth rates are higher and fatigue-crack-growth thresholds are lower in laboratory air, compared to a vacuum or inert gas environment. Cycling magnesium alloys in the presence of a NaCl solution further increases long-crack growth rates compared to laboratory air and also results in accelerated crack formation at corrosion pits.…”

Section: Introductionmentioning

confidence: 70%

“…The use of cast magnesium as a structural material requires a detailed understanding of the material response to cycling loading conditions. Previous work has characterized the fatigue properties of various wrought [1][2][3][4][5][6] and cast [5][6][7][8][9][10][11][12][13][14][15] magnesium alloys. However, a detailed understanding of fatigue mechanisms operating in cast magnesium alloys is still needed in order to develop microstructure-based fatigue-life prediction tools, and thus, facilitate optimal casting design.…”

Section: Introductionmentioning

confidence: 99%

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In-situ observations of low-cycle fatigue damage in cast AM60B magnesium in an environmental scanning electron microscope

Gall

Biallas

Maier

et al. 2004

Metall Mater Trans A

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We present in-situ observations of low-cycle fatigue damage in cast AM60B magnesium. The in-situ fatigue tests were conducted in an environmental scanning electron microscope under both high vacuum and 20 Torr of water vapor. In both environments, fatigue cracks were observed to form and grow within the dendrite cells and through the interdendritic regions. Crack formation and growth through the dendrite cells proceeded along persistent slip bands. The persistent slip bands were typically oriented at about 45 deg with respect to the loading axis and were more frequently observed in relatively large dendrite cells. Crack formation and growth through the Mg interdendritic regions, laden with Al-Mg intermetallic particles, was facilitated by slip incompatibilities in adjacent dendrite cells, microporosity, and damaged second-phase particles. The detectable "crack-formation" size at slip bands and within interdendritic regions was typically equivalent to the dendrite cell size (DCS), since cracks rapidly spanned this distance once nucleated. Cracks formed during cycling in vacuum were more uniformly distributed and showed a lack of complete closure upon unloading, in contrast to cracks formed during cycling in water vapor. The cracks formed in water vapor were much more isolated and showed indication of significant environmental attack and associated embrittlement at the crack tip, as evidenced by the near-perfect mating of crack faces upon unloading. Final fracture occurred by the coalescence of numerous cracks throughout the microstructure, distributed differently depending on the testing environment. The water-vapor environment accelerated the formation of selected, isolated cracks, leading to more localized damage compared to the highly distributed damage growth and coalescence observed in the material cycled in vacuum.

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Section: Introductionmentioning

confidence: 70%

Section: Introductionmentioning

confidence: 99%

In-situ observations of low-cycle fatigue damage in cast AM60B magnesium in an environmental scanning electron microscope

Gall

Biallas

Maier

et al. 2004

Metall Mater Trans A

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Influence of porosity and environmental impact on fatigue life of magnesium alloys

Heuler

Grimm²,

Fuhrmann

et al. 2008

Materialwissenschaft Werkst

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Based on experimental investigations using specimens with different grades of porosity, a significant influence of the material condition of die-cast magnesium alloys on the accuracy of fatigue-life estimation according to the local-strain approach is verified if the data-base is not related to the microstructure of the component. In order to address this transferability issue, a porosity-depending formulation is proposed. Based on a sensitivity analysis, a simplified, empirical engineering approach has been derived that describes the effect of the inherent porosity on fatigue strength via the fatiguestrength exponent b. Furthermore, it is shown that the degradation of the fatigue-behaviour in chloride-containing media is not simply determined by the external corrosive attack, but also influenced by inner defects competing with the environmental impact.

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Aluminium alloys exposed to borderline solutions – a methodology to evaluate the susceptibility to corrosion fatigue with respect to corrosive de‐icers

Troßmann¹,

Bauer

et al. 2011

Materialwissenschaft Werkst

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In addition to high mechanical loads certain components for the automotive industry are exposed to corrosive environments, especially during winter, when corrosion promoting de‐icers are essential to sustain road traffic. The underlying research work contributes to the evaluation of the corrosion fatigue performance of aluminium alloys relevant for automotive application generally, while the present text focuses on wrought alloys. Aluminium alloys are of special interest because of the opportunity to reduce expenses for an additional corrosion protection and to support lightweight construction of vehicles. Components exposed to simultaneous mechanical and corrosive service loads as well as corrosion tests of different scale level (immersion and cabinet testing, long term outdoor exposure of components, usage on test carriers) were analysed to evaluate typical forms of corrosion. Based upon the prevailing damaging mechanism of material conditions with known differences in susceptibility to specific forms of corrosion, like intergranular corrosion or pitting, methods were derived to evolve service relevant types of corrosion during laboratory tests.

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Langsames Ermüdungsrisswachstum in Aluminium- und Magnesiumgusslegierungen in Raumluft und in Vakuum

Cited by 7 publications

References 24 publications

In-situ observations of low-cycle fatigue damage in cast AM60B magnesium in an environmental scanning electron microscope

In-situ observations of low-cycle fatigue damage in cast AM60B magnesium in an environmental scanning electron microscope

Influence of porosity and environmental impact on fatigue life of magnesium alloys

Aluminium alloys exposed to borderline solutions – a methodology to evaluate the susceptibility to corrosion fatigue with respect to corrosive de‐icers

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