Practical failure analysis

, Volume 2, Issue 2, pp 51–57 | Cite as

Failure analysis of gas turbine last stage bucket made of udimet 500 superalloy

  • Z. Mazur
  • J. Kubiak
  • C. Mariño-Lopez
Peer Reviewed Articles
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Abstract

This article presents a failure analysis of 37.5 mW gas turbine third stage buckets made of Udimet 500 superalloy. The buckets experienced repetitive integral tip shroud fractures assisted by a low temperature (type II) hot corrosion. A detailed analysis was carried out on elements thought to have influenced the failure process:
  1. a)

    the stress increase from the loss of a load bearing cross-sectional area of the bucket tip shroud by the conversion of metal to the corrosion product (scale),

     
  2. b)

    influence of the tip shroud microstructure (e.g., a presence of equiaxed and columnar grains, their distribution and orientation),

     
  3. c)

    evidence of the transgranular initiation, and

     
  4. d)

    intergranular creep mechanism propagation.

     

The most probable cause of the bucket damage was the combination of increased stresses due to corrosion-induced thinning of the tip shroud and unfavorable microstructures in the tip shroud region.

Keywords

hot corrosion creep fatigue equiaxed grains columnar grains gas turbine buckets 
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Copyright information

© ASM International - The Materials Information Society 2002

Authors and Affiliations

  • Z. Mazur
    • 1
  • J. Kubiak
    • 1
  • C. Mariño-Lopez
    • 1
  1. 1.Instituto de Investigaciones EléctricasTemixco, MorelosMéxico

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