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Welding over primer coating

      Weld defect characterization

Weld deffects
- Porosity, mostly H2

  • Wormholes
  • Isolated, some CO-CO2,
    and some Zn(V)
-Weld cracking-HIC
hydro01.jpg (80915 bytes)

hydro02.jpg (79937 bytes)
      Porosity Mitigation Strategy
  • [H]-[O] Relationship - Through Flux Design, Increasing Oxygen can decrease Hydrogen in the Weld Metal
  • Oxidizing Flux Ingredients Additions - FeO, Fe2O3, SiO2, CaCO3, and Combinations of these Oxides
  • [H]-[F] Relationship - MnF3 Addition: 4 Electrodes with Oxidizing Ingredients and different levels of MnF3

      [H]-[O], [H]-[F], Metallographic, and Mechanical Properties Data
  • The electrodes containing oxidizing ingredients were more efficient in lowering weld metal diffusible hydrogen content.
  • The electrodes containing MnF3 provided some grain refinement, more AF and little GBF or FS in the as-welded condition.
  • Electrodes with both oxidizing ingredients and MnF3 performed the best overall for diffusible hydrogen reduction at greater primer thickness.
  • At optimized concentrations, oxidizing ingredients and MnF3 produced welds with the best overall combination of mechanical properties (YS/UTS/CVN/Elongation).

Send comments & questions to sliu@mines.edu
Last modified: January 20, 2000