Wyniki wyszukiwania - BazTech

1

Hydrogen embrittlement and wear of magnesium alloys

Dietzel W., Srinivasan P. Bala

Problemy Eksploatacji

|

2010

|

nr 2

101-111

EN

Lightweight combined with good mechanical properties makes magnesium alloys attractive for many applications. However, these alloys have a poor resistance against corrosion. Associated with the corrosion of magnesium alloys is hydrogen embrittlement of the material, since, in the corrosion reaction, atomic hydrogen is generated which partly enters the material and leads to cracking. Another matter of concern for magnesium alloys is their low wear resistance, owing to the inherent low hardness of the material. The influence plasma electrolytic oxidation (PEO) coating on the tribological characteristics of an AM50 magnesium alloy assessed by dry sliding wear tests and the associated wear mechanisms are discussed in this paper.

PL

Niska waga połączona z dobrymi właściwościami mechanicznymi czynią stopy magnezu atrakcyjnymi w wielu zastosowaniach. Jednak stopy te wykazują niską odporność na korozję. Z korozją związana jest kruchość wodorowa stopów magnezu, wynikająca z wydzielaniem w trakcie reakcji korozyjnych wodoru atomowego, który częściowo wnika do materiału i prowadzi do pękania. Kolejnym zagadnieniem jest niska odporność stopów magnezu na zużycie cierne. W pracy przedstawiono wpływ utleniania plazmowo-elektrolitycznego (PEO) na charakterystykę tribologiczną stopu AM58 w warunkach tarcia suchego oraz związane z nią mechanizmy zużycia.

2

Studying hydrogen embrittlement of metals by elastic-plastic methods.

Dietzel W., Pfuff M.

Prace Naukowe Instytutu Materiałoznawstwa i Mechaniki Technicznej Politechniki Wrocławskiej. Konferencje

|

2007

|

Vol. 65, nr 11

3-11

EN

Fracture mechanics based test and evaluation techniques are used to gain insight into the phenomenon of stress corrosion cracking (SCC) and to develop guidance for avoiding or controlling SCC. In particular, experiments that arc based on rising load or rising displacement methods are well suited to study cases of SCC and hydrogen embrittlement (HE) of high strength steels, aluminium and titanium alloys, and to characterise the susceptibility of these materials to environmentally assisted cracking. Rising displacement tests on pre-cracked specimens have also proved to be well suited for studying SCC mechanisms and to model the degradation of metallic materials caused by the uptake of atomic hydrogen from the corrosive environment. Measurement of the crack tip opening angle, CTOA, or, equivalent to this, the ratio between crack growth velocity and the applied deformation rate allows a comparison with models that simulate the mechanism leading to HE.

3

Stress corrosion cracking of magnesium

Winzer N., Song G., Atrens A., Dietzel W., Kainer K.U.

Advances in Materials Science

|

2007

|

Vol. 7, nr 1(11)

83-92

EN

The increased use of Mg-alloys for stressed automotive components has created a demand for a better mechanistic under-standing of the environmental and mechanical influences contributing to Transgranular Stress Corrosion Cracking (TGSCC). TGSCC is the inherent mode of failure for Mg alloys exposed to aqueous environments below their yield stress. It is gener-ally accepted that the predominant mechanism(s) for TGSCC is a type of Hydrogen Assisted Cracking (HAC); however, the specific nature of this mechanism(s) is equivocal. The most commonly proposed mechanism is Delayed Hydride Cracking (DHC). This work investigates its tenability by comparing experimental measurements of the stress corrosion crack velocity, Vc with predictions based on a numerical model for DHC. The measured velocity was in the range of 7x10-10 m/s to 5x10-9 m/s. The initial prediction of the DHC model is 5x10-7 m/s. An investigation into the sensitivity of the model to input parameters is currently underway.