August 21, 2014
Q: I recently saw a comment that regular stick electrodes could be overdried in ovens to the point of causing poor weld performance. Is this true? We store all our electrodes, including low-hydrogen, at 135 to 140 degrees F at all times and have not noticed any problems. We are located in Arizona, with typical humidity in the 10 to 15 percent range or lower.
A: To address your question properly, some clarification must be made. Carbon steel shielded metal arc welding (SMAW) electrodes are classified by their coating and slag types. Depending on the type, the electrode usability could be identified for flat and horizontal welding or all-position welding. Additionally, the coating type can limit the polarity in which the electrode will perform. The AWS specification for carbon steel electrodes for SMAW (AWS 5.1) lists this information and the coating and slag types as well as the usability. The specification also lists the mechanical properties, chemical analysis, and the tolerances for coating concentricity that each electrode classification must meet.
Storing the cellulosic electrodes (E6010 and E6011) in the same oven as the low-hydrogen electrodes (E7015, E7016, E7018, E7018M, E7028, and E7048) can have a negative effect on the electrodes’ performance. A 6010 or cellulosic electrode has a moisture content of approximately 4 to 6 percent. The low-hydrogen electrodes as manufactured have moisture content of about 0.1 to 0.4 percent, and they are usually packaged in hermetically sealed cans or vacuum-packed. If these electrodes are stored in the same holding oven at 135 to 140 degrees F, the higher moisture from the E6010 will be absorbed into the coating. Although the performance may not appear to be affected, the elevated moisture content in the E7018 may not yield a low-hydrogen deposit.
Most manufacturers recommend that low-hydrogen electrodes be stored at 225 to 300 degrees F. Comparatively, the cellulosic types usually are not put in a holding oven because moisture pickup generally has no effect on performance. If both electrodes were stored in the same holding oven at the higher temperature, the 7018 would obtain higher moisture content and the 6010 electrode would perform poorly because the moisture in its coating would be too low to give the electrode sufficient energy or arc force throughout the entire electrode. This arc energy helps control weld penetration. If these electrodes absorb too much moisture, they will exhibit very poor arc direction, excess spatter, and even porosity.
Figure 1 lists several of the most common carbon steel electrodes and their holding temperatures. For more precise numbers, you should contact your distributor. Stainless steel electrodes should be stored at temperatures equivalent to the carbon steel low-hydrogen types.
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