The influence of consumable composition and solidification on inclusion formation and growth in low carbon steel underwater wet welds
- Colorado School of Mines, Golden, CO (United States)
The use of underwater wet welding for offshore repairs has been limited mainly because of porosity in the resulting welds. With appropriate consumable design, however, it is possible to enhance weld metal toughness and reduce porosity. Surface and underwater wet welds, obtained with E6013 grade electrodes modified with systematic titanium and boron additions, were prepared and analyzed to explain, in terms of the fundamentals of inclusion formation during weld solidification, any increase in acicular ferrite. It was demonstrated that in underwater wet welding, over 60% vol. acicular ferrite can be obtained, through titanium and boron additions to the electrode covering. The presence of titanium resulted in the formation of inclusions which assisted the formation of acicular ferrite in the underwater welds and countered the rapid quenching effect of the underwater environment. Boron additions decreased the amount of grain boundary ferrite, further improving the microstructure. It was shown that the weld metal titanium and boron compositional ranges for acicular ferrite maximization varied with the heat input and the cooling rate. Porosity reduction was possible through the addition of calcium carbonate at approximately 13% wt. in the flux covering. However, weld metal decarburization also occurred with the addition. The Zener diameter approach was used to relate the inclusion size and austenite grain size, and to explain the resulting microstructure.
- OSTI ID:
- 72653
- Journal Information:
- Bulletin - Welding Research Council, Journal Name: Bulletin - Welding Research Council Journal Issue: 399; ISSN 0043-2326; ISSN WRCBA2
- Country of Publication:
- United States
- Language:
- English
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