Weldforce 202T AC/DC
© Weldclass 2020 | E.&O.E. 49
12.3 Main Weld Current
12.3.1 DC Current
DC or Direct Current is where the welding current flows in only one direction. With a DC circuit 70% of
the energy or heat is always on the positive side.
DC is used for welding the following materials:
• Mild Steel
• Stainless Steel
• Copper
• Titanium
12.3.2 AC Current
AC or Alternating Current is where the welding current flow oscillates back and forth in both directions.
When reactive metals are exposed to air they form an oxide layer that insulates the base metal and
prevents welding current flowing. It also contaminates the weld pool. Reverse current flow is required
to break through/ clean off this oxide layer so that welding can take place, while the current flow during
the positive cycle does the majority of the heating of the weld pool area.
AC is used for welding the following materials:
• Aluminium
• Aluminium Alloys
• Magnesium
• Zinc
Figure 48
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