Root cause analysis on failed screws in an industrial turbine

EasyChair Preprint no. 453

Abstract

The failed screws of an industrial turbine hot section have been investigated. The broken screws were found during scheduled inspection of turbine with boroscope. Mechanical testing, optical microscopy (OM) and scanning electron microscopy (SEM) observation have been carried out on failed screws. The most crack positions were below the screws heads and cracks have propagated into center. Analysis results identified unexpected Cadmium element on both fractured surfaces and screw body. Couple material (Ni superalloy-cadmium element), along with high temperature of combustor section and static load, resulted to liquid metal embrittlement (LME). As results of the present work, other similar failures were prohibited.

Keyphrases: cadmium element, failed screws, Industrial turbine, LME

@Booklet{EasyChair:453,
  author = {Saeid Shahrzad and Reza Mousavipour and Meisam Khodabakhshi and Masoud Vatan Ara},
  title = {Root cause analysis on failed screws in an industrial turbine},
  howpublished = {EasyChair Preprint no. 453},

  year = {EasyChair, 2018}}