Hydrogen content of underwater wet welds deposited by rutile and oxidizing electrodes
- PETROBRAS Research and Development Center, Rio de Janeiro (Brazil)
- Colorado School of Mines, Golden, CO (United States). Center for Welding, Joining and Coatings Research
Shielded metal arc wet welding, due to its flexibility and ease of mobilization, is one of the most attractive methods for repair of underwater structures. However, the quality of the weld metals deposited by this process is detrimentally affected by the direct contact of the welding arc with the aqueous environment. Oxygen and hydrogen generated by the decomposition of water in the arc are responsible for the main problems related to this specific process: loss of deoxidizers, oxygen pickup, increase in oxide inclusions content, hydrogen-induced cracking, and porosity. Rutile electrodes are recognized in the literature as being able to deposit welds with adequate mechanical properties but with high hydrogen content. Oxidizing electrodes, on the other hand, are able to deposit welds with lower hydrogen content but higher oxygen content. Welds deposited by rutile electrodes presented approximately 90 ml/100g of diffusible hydrogen while oxidizing electrodes produced welds with diffusible hydrogen contents varying from 40 to 50 ml/100g. It was found that the measured diffusible hydrogen contents of underwater wet welds are more dependent on the type of electrode covering than on the weld metal oxygen content. The residual hydrogen content of underwater welds showed a tendency to increase to a constant level of approximately 5 ml/100g as the oxygen content of the weld increased to the saturation value (0.22 wt.pct.). It seems, therefore, that the diffusible hydrogen content of underwater wet welds is more influenced by the amount of total hydrogen absorbed by the liquid metal before solidification than by the amount of inclusions, acting as hydrogen traps, in the weld metal.
- OSTI ID:
- 403600
- Report Number(s):
- CONF-9606279-; ISBN 0-7918-1492-0; TRN: IM9651%%635
- Resource Relation:
- Conference: 14. international conference on offshore mechanics arctic engineering (OMAE), Florence (Italy), 16-20 Jun 1996; Other Information: PBD: 1996; Related Information: Is Part Of OMAE 1996 -- Proceedings of the 15. international conference on offshore mechanics and arctic engineering. Volume 3: Materials engineering; Salama, M.M. [ed.] [Conoco Inc., Ponca City, OK (United States)]; Toyoda, Masao [ed.] [Osaka Univ. (Japan)]; Liu, S. [ed.] [Colorado School of Mines, Golden, CO (United States)]; Santos, J.F. dos [ed.] [GKSS, Geesthacht (Germany)]; Stacey, A. [ed.] [Health and Safety Executive, London (United Kingdom)]; Tubby, P.; Pisarski, H. [eds.] [TWI, Cambridge (United Kingdom)]; PB: 579 p.
- Country of Publication:
- United States
- Language:
- English
Similar Records
Effects of the electrode oxidizing potential on underwater wet welds
Use of nickel to improve the mechanical properties of high oxygen underwater wet welds