Effect of solidification cooling rate on the fatigue life of A356.2-T6 cast aluminium alloy

B. Zhang, W. Chen, D. R. Poirier

Research output: Contribution to journalArticle

52 Scopus citations

Abstract

The effect of the cooling rate during solidification on the fatigue life of a cast aluminium alloy (A356.2-T6) is examined. The fatigue lives were determined for specimens removed from ingots with a gradient in cooling rates along their heights. Low- and high-cycle fatigue tests were conducted under both axial loading and reciprocating-bending conditions at a stress (strain) ratio (R) of -1.0, 0.1 and 0.2. Results show that the fatigue life decreases by a factor of three in low-cycle fatigue (R = -1.0) and by a factor of 100 in high-cycle fatigue (R = 0.1) as solidification cooling rate decreases from ∼10 to ∼0.3 Ks-1, as indicated by measurements of the secondary dendrite arm spacings in the ingots. Fatigue cracks initiated from porosity in the material solidified at slower cooling rates. When pore size is below a critical size of ∼80 μm, as a result of increasing the cooling rate, the fatigue cracks initiated from near-surface eutectic-microconstituent. When present at or near the surface, large oxide inclusions initiated fatigue cracks.

Original languageEnglish (US)
Pages (from-to)417-423
Number of pages7
JournalFatigue and Fracture of Engineering Materials and Structures
Volume23
Issue number5
DOIs
StatePublished - May 2000

Keywords

  • Cast aluminium
  • Cooling rate
  • Crack initiation
  • Fatigue life
  • Microporosity
  • Secondary dendrite arm spacing

ASJC Scopus subject areas

  • Materials Science(all)
  • Mechanics of Materials
  • Mechanical Engineering

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