Newb question

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I just wanted to know the difference between ac and dc welding.
Reply:DC, "direct current" full time, full speed ahead current,  AC stands for “Alternating Current,” meaning voltage or current that changes polarity or direction, respectively, over time.
Reply:Originally Posted by drjuanDC, "direct current" full time, full speed ahead current,  AC stands for “Alternating Current,” meaning voltage or current that changes polarity or direction, respectively, over time.
Reply:a graph of dc is a straight line.a graph of .ac is a sine wave, alternates between positive and negative, passing through zero each wave..wave characteristics can be exploited in  tig welding..aluminum tig is ac, ...aluminum steel  is  dc, electrode negative..stick is mostly preferred dcep but csan be done just fine on ac..
Reply:Historically DC was produced by portable generators in the field.  So you used electrodes that had flux coatings designed for DC.    Power from the grid is normally AC and before the era of solid state circuits DC was a problem to produce in a building.  It was easier to simply have a transformer to produce high amperage currrent from the AC in the building.  AC electrodes allowed one to used grid current easily.  This allowed every farmer who had electric power to weld on his equipment using a simple transformer.  The alternative to produce DC was to have a large AC motor driving a DC generator in the building.  These machines were inefficient and noisy.  The last one I saw in use was over 15 years ago.   From a welding standpoint DC gives a smoother arc but can create magnetic fields that bend the arc creating "arc blow".  AC does not produce arc blow since the direction of current is switching back and forth but the arc is not as smooth.   Today simply discussing AC and DC leaves a large gap in the middle that is being filled with synthesized current that can be a mix of the two in any way you want.  You can have an AC current on top of a DC or an AC current that is square wave rather than sine wave or maybe you want more negative than positive or visa versa and of course how many times a second do you want the effect to happen?
Reply:if you have a DC machine you can use AC or DC electrodes, you can also add a scratch start tig and a bottle of argon for welding carbon steel, but need the hi frequency AC for aluminum, hope this is closer to what your looking for,