Alternative nickel based filler metals for use in the girth welding of bi-metallic pipelines

C. A. Maltin, A. M. Galloway, M Mweemba

Research output: Contribution to journalArticle

Abstract

The highest grade of carbon steel which may be used as a substrate material in bi-metallic pipelines is being limited to API 5L X65 by the as welded yield strength of the filler metals currently employed for girth welding. An investigation has been carried out to assess the suitability of three alternative
nickel based filler metals for this application: Inconel 617, Inconel 718 and Incoloy 945X. Their viability has been determined through microstructural characterisation and mechanical testing, focusing on tensile strength and impact toughness. Investigations have been carried out into the precipitation of
eutectic type phases within the weld metal and the behaviour of alloying elements resulting in such precipitation. The data presented have indicated that of the three weld metals, Inconel 617 exhibits superior as-welded properties and provides a yield strength sufficient to overmatch the specified minimum yield strength of API 5L X65 pipeline. It has been determined that although Nb additions are essential to promote the precipitation strengthening, its segregation to the interdendritic region during solidification leads to the formation of an incoherent eutectic type precipitate. As a result of the lower
volume fraction of eutectic type precipitate, Inconel 617 also demonstrated superior impact toughness properties.
LanguageEnglish
Number of pages63
JournalMetallurgical and Materials Transactions A
Publication statusIn preparation - 2014

Fingerprint

Inconel (trademark)
Filler metals
Nickel
fillers
welding
Yield stress
Welding
yield strength
Pipelines
nickel
Application programming interfaces (API)
application programming interface
Eutectics
Fracture toughness
Precipitates
Welds
toughness
Metals
eutectics
metals

Keywords

  • nikel-based filler metals
  • weld metals
  • bi-metallic pipelines
  • as welding
  • yield strength

Cite this

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title = "Alternative nickel based filler metals for use in the girth welding of bi-metallic pipelines",
abstract = "The highest grade of carbon steel which may be used as a substrate material in bi-metallic pipelines is being limited to API 5L X65 by the as welded yield strength of the filler metals currently employed for girth welding. An investigation has been carried out to assess the suitability of three alternativenickel based filler metals for this application: Inconel 617, Inconel 718 and Incoloy 945X. Their viability has been determined through microstructural characterisation and mechanical testing, focusing on tensile strength and impact toughness. Investigations have been carried out into the precipitation ofeutectic type phases within the weld metal and the behaviour of alloying elements resulting in such precipitation. The data presented have indicated that of the three weld metals, Inconel 617 exhibits superior as-welded properties and provides a yield strength sufficient to overmatch the specified minimum yield strength of API 5L X65 pipeline. It has been determined that although Nb additions are essential to promote the precipitation strengthening, its segregation to the interdendritic region during solidification leads to the formation of an incoherent eutectic type precipitate. As a result of the lowervolume fraction of eutectic type precipitate, Inconel 617 also demonstrated superior impact toughness properties.",
keywords = "nikel-based filler metals, weld metals, bi-metallic pipelines, as welding, yield strength",
author = "Maltin, {C. A.} and Galloway, {A. M.} and M Mweemba",
year = "2014",
language = "English",
journal = "Metallurgical and Materials Transactions A",
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TY - JOUR

T1 - Alternative nickel based filler metals for use in the girth welding of bi-metallic pipelines

AU - Maltin, C. A.

AU - Galloway, A. M.

AU - Mweemba, M

PY - 2014

Y1 - 2014

N2 - The highest grade of carbon steel which may be used as a substrate material in bi-metallic pipelines is being limited to API 5L X65 by the as welded yield strength of the filler metals currently employed for girth welding. An investigation has been carried out to assess the suitability of three alternativenickel based filler metals for this application: Inconel 617, Inconel 718 and Incoloy 945X. Their viability has been determined through microstructural characterisation and mechanical testing, focusing on tensile strength and impact toughness. Investigations have been carried out into the precipitation ofeutectic type phases within the weld metal and the behaviour of alloying elements resulting in such precipitation. The data presented have indicated that of the three weld metals, Inconel 617 exhibits superior as-welded properties and provides a yield strength sufficient to overmatch the specified minimum yield strength of API 5L X65 pipeline. It has been determined that although Nb additions are essential to promote the precipitation strengthening, its segregation to the interdendritic region during solidification leads to the formation of an incoherent eutectic type precipitate. As a result of the lowervolume fraction of eutectic type precipitate, Inconel 617 also demonstrated superior impact toughness properties.

AB - The highest grade of carbon steel which may be used as a substrate material in bi-metallic pipelines is being limited to API 5L X65 by the as welded yield strength of the filler metals currently employed for girth welding. An investigation has been carried out to assess the suitability of three alternativenickel based filler metals for this application: Inconel 617, Inconel 718 and Incoloy 945X. Their viability has been determined through microstructural characterisation and mechanical testing, focusing on tensile strength and impact toughness. Investigations have been carried out into the precipitation ofeutectic type phases within the weld metal and the behaviour of alloying elements resulting in such precipitation. The data presented have indicated that of the three weld metals, Inconel 617 exhibits superior as-welded properties and provides a yield strength sufficient to overmatch the specified minimum yield strength of API 5L X65 pipeline. It has been determined that although Nb additions are essential to promote the precipitation strengthening, its segregation to the interdendritic region during solidification leads to the formation of an incoherent eutectic type precipitate. As a result of the lowervolume fraction of eutectic type precipitate, Inconel 617 also demonstrated superior impact toughness properties.

KW - nikel-based filler metals

KW - weld metals

KW - bi-metallic pipelines

KW - as welding

KW - yield strength

M3 - Article

JO - Metallurgical and Materials Transactions A

T2 - Metallurgical and Materials Transactions A

JF - Metallurgical and Materials Transactions A

SN - 1073-5623

ER -