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Effect of titanium addition on the microstructure and inclusion formation in submerged arc welded HSLA pipeline steel

Beidokhti, B ; Sharif University of Technology | 2009

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  1. Type of Document: Article
  2. DOI: 10.1016/j.jmatprotec.2008.09.021
  3. Publisher: 2009
  4. Abstract:
  5. The effect of titanium addition on the SAW weld metal microstructure of API 5L-X70 pipeline steel was investigated. The relationship between microstructure and toughness of the weld deposit was studied by means of full metallographic, longitudinal tensile, Charpy-V notch and HIC 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 and 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 quasi-cleavage. The results showed an increase in the titanium content of inclusions with increased titanium levels of weld metal. Titanium-base inclusions improve impact toughness by increasing the formation of acicular ferrite in the microstructure. No HIC susceptibility was found in the weld metals with titanium contents less than 0.09%. © 2008 Elsevier B.V. All rights reserved
  6. Keywords:
  7. Inclusion ; Acicular ferrite ; Charpy-v ; Ductile ; Grain-boundary ; Impact properties ; Impact toughness ; Inclusion formations ; Longitudinal tensile ; Mode of fractures ; Pipeline steels ; Quasi cleavages ; Submerged arc welded ; Titanium contents ; Weld beads ; Weld deposits ; Weld metals ; X-70 pipeline steels ; Acoustic surface wave devices ; Ductile fracture ; Electric welding ; Ferrite ; Inclusions ; Microstructure ; Pipelines ; Steel ; Steel pipe ; Submerged arc welding ; Welded steel structures ; Welds ; Titanium
  8. Source: Journal of Materials Processing Technology ; Volume 209, Issue 8 , 2009 , Pages 4027-4035 ; 09240136 (ISSN)
  9. URL: https://www.sciencedirect.com/science/article/abs/pii/S0924013608007048