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Metallurgical Characterization of Dissimilar Metal Welds in Grade F65 Steel to Grade F22 Steel Overlaid with Low Alloy Steel Filler Metal Using Inconel Alloy 625



  • The oil and gas industry uses dissimilar metal weld (DMW) overlays or “butter” layers to eliminate the need for post weld heat treatment after final field welding
  • Reported hydrogen assisted cracking (HAC) failures of conventional Alloy 625 butter welds on 8630 steel forgings led to the development of alternative processes using low alloy steel (LAS) butter welds in place of Alloy 625
  • Final closure welds between LAS butter layer and F65 pipe are made using Alloy 625 filler metal without a final post weld heat treatment
  • Using a LAS butter weld in place of Alloy 625 shifts the HAC susceptible interface to the closure weld


Industry Sponsor: OneSubsea

Faculty: Boian Alexandrov (OSU)

Graduate Student: Ryan Buntain

Industry Contact: Dean Hannam