Creep-fatigue-environment interaction at the propagating crack tip in MAR-M200+Hf alloy

E. Aghion, M. Bamberger, A. Berkovits

Research output: Contribution to journalConference articlepeer-review

1 Scopus citations

Abstract

Unidirectional solidified MAR-M200+Hf nickel-base superalloy failed under a low-cycle fatigue (LCF) loading regime at 975°C. The cycle comprised creep by tension and plasticity compression loading. It was found that the chemical reaction between the gas and the alloy at the propagating crack tip controls LCF failure. Under argon the propagation of the crack was transdendritic without interaction with the environment. Under oxygen, ahead of the crack tip a uniphase layer develops, composed of coarsening γ′ - phase material, internally oxidized. At the propagating crack other effects were observed: branching and blunting which prolonged the LCF life. Under CO2, layers of oxycarbides and graphite-like material develop. In both cases the crack propagates through interdendritic segregation zones. Under nitrogen, propagation is transdendritic with coarse nitrides which develop ahead of the crack tip. Under a mixture of the gases: Ar+20%O2, N2+20%O2 and 50%N2+50%CO2, a mixed fracture was observed and a linear synergistic failure model is proposed.

Original languageEnglish
Pages (from-to)225-229
Number of pages5
JournalIsrael Journal of Technology
Volume24
Issue number1 -2,pt A
StatePublished - 1 Dec 1988
Externally publishedYes
EventFourth Israel Materials Engineering Conference - I.M.E.C. IV - Beer Sheva, Isr
Duration: 7 Dec 19888 Dec 1988

ASJC Scopus subject areas

  • General Engineering

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