I could see the text explaining DCEN gives more penetration. but could not understand why only in FCAW (not in SMAW or GMAW) it is preferred
Hi Nivas,
Heat partitioning is different when you are using covered electrode or TIG welding. DCEN when using covered electrode (SMAW - stick welding) would accumulate about 30% of the heat on the work piece resulting in more melt off rate and shallow penetration. This is not only the result of polarity. The coating on the electrode affects the heat distribution. The true effect of only polarity is observed in GTAW (TIG welding) where there is no coating on the filler metal (electrode - naming it as "electrode" is not correct as it does not have electrical current on it but...). And GTAW the heat partitioning is completely the opposite to that in Shielded Metal Arc Welding (SMAW).
I hope this helps.
Dear Nivas,
I have attached you an illustration of DCEP and DCEN, to show how weld profile changes. Generally, direct current can be either reverse or straight polarity. Flux-cored electrode wires are designed to operate on either DCEP or DCEN. The wires designed for use with an external gas shielding system are generally designed for use with DCEP. Some self-shielding flux-cored ties are used with DCEP while others are developed for use with DCEN. Electrode positive current gives better penetration into the weld joint. Electrode negative current gives lighter penetration and is used for welding thinner metal or metals where there is poor fit-up. The weld created by DCEN is wider and shallower than the weld produced by DCEP. So, it is widely depends on your applications.
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