Serkan Orhan, 030070165, 11th week Part4

4)Reducing Flame [Group:Welding]
[New]
The carburizing or reducing flame has excess of acetylene and can be recognized by acetylene feather, which exists between the inner cone and the outer envelope. The outer flame envelope is longer than that of the neutral flame and is usually much brighter in color. With iron and steel, carburizing flame produces very hard, brittle substance known as iron carbide. A reducing flame may be distinguished from carburizing flame by the fact that a carburizing flame contains more acetylene than a reducing flame. A reducing flame has an approximate temperature of 3038C. A carburizing-flame is used in the welding of lead and for carburizing (surface hardening) purpose. A reducing flame, on the other hand, does not carburize the metal; rather it ensures the absence of the oxidizing condition. It is used for welding with low alloy steel rods and for welding those metals, (e.g., non-ferrous) that do not tend to absorb carbon. This flame is very well used for welding high carbon steel.

(Introduction to Basic Manufacturing Process and Workshop Technology, Rajender Singh,2006, p. 313)

5)Oxidizing Flame [Group:Welding]

[New]

The oxidizing Baum] has an excess of oxygen over the acetylene. An iodizing Barg can be recognized by the small cone, which is shortet; much bluer in color and more pointed than that of the neutral f aMne. The outer fWzie envelope is much shorter and tends to fan out at the end. Such a flame makes a loud roaring sound. It is the hottest flame (temperature as high as 6300F) produced by any oxy-fuel gas source. But the excess oxygen especially at high temperatures tends to combine with many metals to form hard, brittle, low strength oxides. Moreover; an excess of oxygen causes the weld bead and the surrounding area to have a scummy or dirty appearance. For these reasons, an oxidizing fladie is of limited use in welding. It is not used in the welding of steel. A slightly oxidizing flame is helpful when welding (i) Copper-base metals (ii) Zinc-base metals and (iii)A few types of ferrous metals such as manganese steel and cast iron. The oxidizing atmosphere in these cases, create a base-metal oxide that protects the base metal.

(Introduction to Basic Manufacturing Process and Workshop Technology, Rajender Singh,2006, pp. 313-314)