Akademik Veri Yönetim Sistemi
Welding Journal (Miami, Fla), cilt.84, sa.6, 2005 (SCI-Expanded)
In hyperbaric dry underwater welding, the hyperbaric gas tungsten arc welding (GTAW) procedure offers many advantages. However, determination of the electrode service life is a substantial condition for good results in unmanned and computer-remote-controlled hyperbaric GTAW. Electrode service life is the time in which one electrode can be welded from a polished state to reaching a wear mark as an applied condition criterion under certain conditions. Extending electrode service life can drastically reduce the cost of the process; however, many influencing factors, as well as unpredictable occurrences during hyperbaric GTAW, make exact determination of the electrode service life more difficult. In this study, electrode service life was examined in the dependence on the electrode type, arc current, and arc power under different ambient pressure levels. For determining service life of the electrodes in hyperbaric GTAW, wear rate (percentage shortening of the electrode point due to wear) was considered as an evaluation criterion, because the wear rate contains all of the above-mentioned parameters and reflects all the effects of them. For the delimitation of the service life tests, two kinds of tungsten electrodes [WL10 (with 1.0% LaO2) and WT 20 (with 2.0% ThO2)] were selected, which are the types predominantly preferred in practice. The results of this work indicate that the electrode service life heavily depends on the type of electrode under high ambient pressure. The WL10 electrode exhibits a longer arc-on time and a greater electrical load capacity and, therefore, a longer service life than the WT20 electrode. The compiled formulas for the computation of the electrode service life have an empirical form, which can be used for estimation as well as for comparison of the service life of electrodes in hyperbaric GTAW. The provided service life diagrams as a function of ambient pressure and arc power, in which the test results are represented, can be of great relevance for use both in onshore and offshore technology, especially in performing reproducible, high-quality welded underwater joints.