MMA Welding Carbon SteelMMA welding is one of the most widely used processes for welding carbon steels. It is a versatile process, relatively inexpensive to equip and suitable for shop and site work. Welding equipment may be AC or DC, using transformers, transformer-rectifiers and engine-driven generators. MMA electrodes for welding of carbon steel have mild steel cores covered with a flux coating. There are several types of coating, the most popular being rutile, basic, and cellulosic. Each imparts different characteristics to the electrode that affect the ease of use, positional capability and quality of weld metal. Rutiles are normally the easiest to use, basics generally give best quality welds, and cellulosics have all-positional capability. The weldability of the steel may impose restrictions on the choice of electrode. Steels with carbon contents above about 0.3% are hardenable, and fast cooling will produce a hard HAZ and this is liable to result in hydrogen cracking. This form of cracking can be prevented by use of preheat, basic (low hydrogen) electrodes and suitable welding procedures. MMA welding may present possible electrical and radiation hazards plus particulate welding fume depending on electrode size and current.
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