Delayed fracture of high strength steels under atmospheric corrosion

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3 Citations (Scopus)

Abstract

Notch tensile strengths (NTSs) of circumferentially notched round bar specimens of high strength steels were measured after hydrogen precharging using SSRT, and power law relationship between NTS and hydrogen concentrationwas found. The occurrence of delayed fracture during constant load test of atmospherically corroded specimenscorresponded to the balance between critical hydrogen concentration for delayed fracture (HC) and hydrogenconcentration from the environment (HE). This fact suggests that the delayed fracture of actual high strength boltalso occurs when HE exceeds HC. Delayed fracture properties of high strength steels were successfully evaluatedusing SSRT after atmospheric corrosion to take into consideration the hydrogen entry caused by atmospheric corrosion.The ultrahigh strength steel containing hydrogen traps possesses relatively high HC. However, the hydrogentraps resulted in an increase of HE, so that the resistance to delayed fracture was not improved. Hydrogen entryunder cyclic corrosion test monitored by electrochemical hydrogen permeation test indicated an increase of hydrogenentry with time probably because of enhancement of hydrogen entry caused by the changes of pH of inner rust layer and potential. It is suggested that the "delayquot; of delayed fracture is the time required for the enhancement ofthe hydrogen entry efficiency.

Original languageEnglish
Pages (from-to)184-189
Number of pages6
JournalZairyo to Kankyo/ Corrosion Engineering
Volume60
Issue number4
DOIs
Publication statusPublished - 2011

Keywords

  • Atmospheric corrosion
  • Cyclic corrosion test
  • Delayed fracture
  • Electrochemical hydrogen permeation test
  • Exposure test
  • High strength steel
  • Hydrogen embrittlement
  • Hydrogen trap
  • Slow strain rate test

ASJC Scopus subject areas

  • Surfaces, Coatings and Films
  • Metals and Alloys
  • Electrochemistry
  • Materials Chemistry

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