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The change in the chemical composition and toughness of API 5L-X70 welds by addition of titanium

  • Behrooz Beidokhti*
  • , Amir Hosein Koukabi
  • , Abolghasem Dolati
  • , Peng He
  • *Corresponding author for this work
  • Sharif University of Technology
  • Harbin Institute of Technology

Research output: Contribution to journalArticlepeer-review

Abstract

The objective of this work was to study the influence of titanium variations on the API 5L-X70 steel weld metal properties. The relationship between microstructure and toughness of the weld deposit was studied by means of full metallographic, longitudinal tensile and Charpy-V notch tests on the specimens cut transversely to the weld beads. The best combination of microstructure and impact properties was obtained in the range of 0.02-0.05% titanium. By further increasing of titanium content, the microstructure was changed from a mixture of acicular ferrite, grain-boundary ferrite, Widmanstätten ferrite to a mixture of acicular ferrite, grain-boundary ferrite, bainite and ferrite with M/A microconstituent. Therefore, the mode of fracture also changed from dimpled ductile to quasicleavage. Titanium-base inclusions improve impact toughness by increasing the formation of acicular ferrite in the microstructure. The amount of manganese in inclusions was decreased with addition of titanium to the weld metal.

Original languageEnglish
Pages (from-to)1209-1216
Number of pages8
JournalInternational Journal of Modern Physics B
Volume23
Issue number6-7
DOIs
StatePublished - 20 Mar 2009
Externally publishedYes

Keywords

  • Bainite
  • Manganese.
  • Quasi-cleavage
  • Titanium

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