Development of Nondestructive On-Site Measurement Techniques by Means, of an Electrochemical Method for Material Degradation of S/H SUS Steel Tubes of Fossil Boilers

Yoshihisa Saito, Tetsuo Shoji, Yutaka Watanabe

Research output: Contribution to journalArticlepeer-review

7 Citations (Scopus)

Abstract

The change in electrochemical properties caused by microstructural changes was utilized for the nondestructive detection of material degradation. S/H tubes of fossil boilers were studied where carbide, Laves and sigma phase formation were detected by the anodic current peak Ip in an anodic polarization measurement of 316H stainless steel in 1M KOH electrolytes. For practical uses, a small and light-weight electrochemical probe and a portable anodic polarization measuring system were developed; their effectiveness was shown through on-site measurements in many actual plants. Using measured Ip, the equivalent operational temperature of tubes after long-term service operation was estimated with reference to the Ip-t exp (–Q/RT) curve of aged materials. It is suggested that their metallographic changes can be evaluated by a parameter of Ip/Ipc, where Ipc is estimated as to be the threshold value of Ip. It is also indicated that their mechanical damage markedly increases by nucleation and growth of Laves phases at Ip/Ipc value over 0.7.

Original languageEnglish
Pages (from-to)1442-1448
Number of pages7
JournalTransactions of the Japan Society of Mechanical Engineers Series A
Volume57
Issue number538
DOIs
Publication statusPublished - 1991
Externally publishedYes

Keywords

  • Boiler
  • Electrochemistry
  • Fossil Fuel Fired
  • Life Prediction
  • Nondestructive Inspection
  • Power Generation

ASJC Scopus subject areas

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

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