Characterisation of microstructure, defect and high-cycle-fatigue behaviour in a stainless steel joint processed by brazing

Y. Li, X. Zhang, D. Parfitt, S. Jones, B. Chen

Research output: Contribution to journalArticle

3 Citations (Scopus)
14 Downloads (Pure)

Abstract

We report the characterisation of microstructures and high-cycle-fatigue (HCF) properties of Type 304 stainless steel joints processed by brazing. Pure copper was applied as the filler metal for brazing at 1120 °C. A two-phase microstructure was obtained within the joint region: the star-shaped precipitates and copper matrix. The precipitates with an average size of 0.43 μm were rich in iron and chromium. A fixed orientation relationship was found between the precipitates and copper matrix. The joint exhibited much higher tensile strength and HCF life when compared to pure copper. The strength enhancement can be attributed to the presence of precipitates. Furthermore, the effect of joint interface roughness as well as defects was critically investigated. The joint interface roughness showed little influence on the HCF lives. Post-examinations revealed that fatigue crack initiation and propagation occurred entirely within the joint region, hence being consistent with the similar HCF lives regardless of the pre-defined interface roughness conditions. In addition, it was found that the HCF lives decreased exponentially with the increase of initial defect area. Fractography analysis revealed that fatigue striation spacings near the crack initiation zone increased with the increase of defect area, suggesting that the larger defects result in higher crack growth rate, hence shorten the overall fatigue life.

Original languageEnglish
Pages (from-to)542-552
Number of pages11
JournalMaterials Characterization
Volume151
Early online date29 Mar 2019
DOIs
Publication statusPublished - 1 May 2019

Bibliographical note

NOTICE: this is the author’s version of a work that was accepted for publication in Materials Characterization. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Materials Characterization, [151], (2019) DOI: 10.1016/j.matchar.2019.03.042

© 2019, Elsevier. Licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International http://creativecommons.org/licenses/by-nc-nd/4.0/

Keywords

  • Brazing
  • Defect
  • Fatigue
  • Interface roughness
  • Precipitation
  • Stainless steel

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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