Identification and modeling of fatigue crack growth mechanisms in a die-cast AM50 magnesium alloy

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== Abstract ==
 
== Abstract ==
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We experimentally identified the fatigue  crack  growth micromechanisms  operating  near the limit plasticity  regime in a commercial high-pressure die-cast AM50 alloy  with a critical  review of the available literature.  An existing multistage fatigue model was modified to subsequently recognize these micromechanisms in a threefold fatigue crack growth regime. The formation of the main fatigue crack occurred almost exclusively at shrinkage pores and to a lesser extent at large Mn-rich particles.  At shrinkage  pores,  several  adjacent cracks  typically  incubated  at the edge of flat interdendritic  pores,  propagated along the a-Mg dendrite cells/Al-rich eutectic interface, and rapidly  coalesced  into a main physically small fatigue crack  that advanced  through the Al-rich eutectic. In the long crack regime, the crack advanced in a mixed transdendritic–interdendritic mode along persistent slip bands spreading over several tens of dendrite cells. The model predicts well the fatigue life compared to the experimental data when these observed mechanisms are accounted  for.
  
 
== Introduction ==
 
== Introduction ==

Revision as of 13:18, 6 July 2012

Contents

Abstract

We experimentally identified the fatigue crack growth micromechanisms operating near the limit plasticity regime in a commercial high-pressure die-cast AM50 alloy with a critical review of the available literature. An existing multistage fatigue model was modified to subsequently recognize these micromechanisms in a threefold fatigue crack growth regime. The formation of the main fatigue crack occurred almost exclusively at shrinkage pores and to a lesser extent at large Mn-rich particles. At shrinkage pores, several adjacent cracks typically incubated at the edge of flat interdendritic pores, propagated along the a-Mg dendrite cells/Al-rich eutectic interface, and rapidly coalesced into a main physically small fatigue crack that advanced through the Al-rich eutectic. In the long crack regime, the crack advanced in a mixed transdendritic–interdendritic mode along persistent slip bands spreading over several tens of dendrite cells. The model predicts well the fatigue life compared to the experimental data when these observed mechanisms are accounted for.

Introduction

Results

References


Citation: Identification and modeling of fatigue crack growth mechanisms in a die-cast AM50 magnesium alloy, El Kadiri, H., Xue, Y., Horstemeyer, M.F., Jordon, J.B., Wang, P.T., Acta Materialia, v 54, n 19, p 5061-5076, November, 2006.

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