Journal of Failure Analysis and Prevention

, Volume 7, Issue 4, pp 292–301 | Cite as

Metallurgical Investigation of a Prematurely Failed Concentric Reducer Tube Used in a Hot-Rolling Mill

  • C. D. Singh
  • S. K. Dhua
  • M. Kumar
  • A. K. Jha
  • T. Mrinal
  • K. Sharma
  • R. R. Abhyuday
  • Y. Kumar
Peer Reviewed

Abstract

A concentric reducer tube, which was a part of the top exit roughing hydraulic descaler in a hot strip mill failed prematurely under working pressure. A detailed metallurgical investigation comprising physical examination, optical microscopy, scanning electron microscopy, and electron probe microanalysis was carried out to find out the genesis of the failure. Physical examination revealed cracks located symmetrically around the circumference of the tube that ran along its full length, up to the weld beads at both ends. Optical microscopy of etched samples revealed a banded ferrite-pearlite structure and the existence of forging folds near the change-in-section(160° fillets). Cracks were found to initiate from these forging folds. No structural abnormalities were found in the weld beads and heat-affected zones.

Keywords

Concentric reducer tube Failure analysis Banded structure Forging folds 

Notes

Acknowledgment

The authors express their extreme gratitude for the support and encouragement received from the management of the Research and Development Centre for Iron and Steel, Steel Authority of India Limited, Ranchi (India) during the course of experimental work. Thanks are expressed to the personnel of the metallography laboratory, notably Shri C.B. Sharma, Shri B.B. Patra, and Shri J. Guria at RDCIS for their help in their investigation. We are also immensely thankful to Prof. R.N. Gupta, Prof. R. Prasad, Prof. A.K. Rajak, and Prof. S.N. Roy, Department of Metallurgical Engineering, Bihar Institute of Technology, Sindri.

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Copyright information

© ASM International 2007

Authors and Affiliations

  • C. D. Singh
    • 1
  • S. K. Dhua
    • 1
  • M. Kumar
    • 2
  • A. K. Jha
    • 2
  • T. Mrinal
    • 2
  • K. Sharma
    • 2
  • R. R. Abhyuday
    • 2
  • Y. Kumar
    • 2
  1. 1.R&D Centre for Iron & SteelSteel Authority of India LimitedRanchiIndia
  2. 2.Department of Metallurgical EngineeringBIT SindriDhanbadIndia

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