Blade Lock Ring of 4th Stage Compressor Rotor: Failure Investigation

  • Ashok Kumar Singh Defence Metallurgical Research Laboratory, Hyderabad, India
  • Aginaparru Sambasiva Rao Defence Metallurgical Research Laboratory, Hyderabad, India

Abstract

Present work describes the failure investigation of blade lock ring of 4th stage compressor rotor. The lock ring is fabricated from martensitic stainless steel. The microstructure of failed lock ring is tempered martensite. It shows non-metallic inclusions with three distinct shapes namely, elongated (MnS), globular (Al2O3) and complex shaped (oxy-sulphide). The corrosion pits and corrosion debris are observed in un-etched microstructure and fracture surface, respectively. The tree like branching cracks has observed at several places near surface. These cracks have initiated from the corrosion pits and then propagated inside the material. The interface of inclusions and matrix has also acted as crack initiator.  The lock ring has initially suffered pitting corrosion in service and then cracks have propagated inside the material by stress corrosion cracking.

Published
2019-09-18
How to Cite
Singh, A. K., & Rao, A. S. (2019). Blade Lock Ring of 4th Stage Compressor Rotor: Failure Investigation. International Journal of Engineering Materials and Manufacture, 4(3), 85-95. https://doi.org/10.26776/ijemm.04.03.2019.01
Section
Articles