A reducing oxyfuel gas flame in which there is an excess of fuel gas, resulting in a carbon-rich zone extending around and beyond the cone. See STANDARD WELDING TERMS. See Figure A- 1. See also NEUTRAL FLAME, OXIDIZING FLAME, and REDUCING FLAME.
In an oxyacetylene flame, a carburizing flame is one in which there is an excess of acetylene. The flame has a sharply defined inner cone and a bluish outer flame, but between these, surrounding the cone, is an intermediate white cone. The length of this intermediate or excess-acetylene cone may be considered to be a measure of the amount of excess acetylene in the flame. This flame is sometimes called excess acetylene, or reducing.
A carburizing flame is used in hardfacing and similar processes to obtain a fusion or bond between base metal and weld metal without deep melting of the base metal.