Advantages Of Using Oxy-Acetylene Hardfacing Method

The outstanding of the oxyacetylene method is below: 

Low dilution of the weld deposit,

Good control of the deposit shape, 

Low thermal shock due to slow heating and cooling. 

The oxyacetylene process is not recommended for large components.

Standard gas welding equipment is used in this common process. 

The technique is simple. Anyone familiar with general welding should have no problem learning to hard-facing using this process. 

The surface of the part to be hard-faced must be cleaned, without any rust, scale, grease, dirt, and other foreign materials. Preheat and post-heat the work to minimize the possibility of cracks developing in the deposit or base metal.

The flame adjustment is important in the oxyacetylene method. An excess acetylene feather is recommended for depositing hard-facing rods. A neutral flame or standard feather is produced when the oxygen to acetylene ratio is 1:1. A standard feather flame has two parts; an inner core and an outer envelope. When there is an excess of acetylene, there is a third zone, between the inner core and the outer envelope. This zone is called the excess acetylene feather. An excess acetylene feather is three times as long as the inner cone is desired.

Only the surface of the base metal in the immediate area being hard-faced is brought to the melting temperature. The torch flame is played onto the surface of the material to be hard-faced, keeping the tip of the inner cone just clear of the surface. A small amount of carbon is absorbed into the surface, lowering its melting point and producing a watery, glazed appearance known as ‘sweating’. The hard-facing rod is introduced into the flame and a small drop melted off onto the sweating area, where it spreads quickly and cleanly, in a similar fashion to a brazing alloy.

Then the hard-facing rod is melted and spread over the surface of the base metal. The hard-facing material should not mix with the base metal but should bond with the surface to become a protective new layer. If excessive dilution occurs, the properties of the hard-facing material will be degraded. The surface becomes a protective new layer. If excessive dilution occurs, the properties of the hard-facing material will be degraded.

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