Brazing process

Brazing process

Brazing process

Brazing process is a group of joining processes wherein coalescence is produced by heating to an appropriate temperature and by using a filler metal having a liquidus above 800°F(470°C) and below the solidus of the base metals.


Although brazing is a  process of joining metals together by using an appropriate heating method, it differs from the welding process. 
Brazing associated with melting of a relatively low melting point filler material. Typically, brazing involves comparatively melting point filler content (450℃ ) or below the melting point of the base metal, 

Steps involved in Brazing process

The brazing process involves the following steps:
1-Cleaning and surface preparation 
2- Application of flux on both surfaces of base metal and filler metal.
3-Heating the joint
4-Application of filler metal on to the joint 
5- Cooling of the braze joint and removing the flux residue from the compleated joint.

Difference between Brazing and welding

Brazing process
The main difference between a welded joint and a brazed joint is the penetration. A brazed joint has no penetration into the base metal whereas welded joint achieves penetration into the base metal.
Surfaces to be brazed are not raised to the melting point, rather the joint is produced by the solidification and adhesion of a thin layer of molten filler metal to closely-adjacent mating surfaces; whereas, in welding, the two surfaces to be joined are actually melted.
Weld bead shows ripples whereas a brazed joint does not because the molten brazing filler alloy spreads along the joint whereas molten filler metal in welding solidifies almost at the same place where it melts.

Joint design for Brazing

The controlled closed fit between the surfaces to be joined is essential in the brazing process.
It is kept in mind that the joint should  meet service requirements such as
Mechanical performance, Electrical and Thermal conductivity, Pressure tightness, corrosion resistance, service temperature and good appearance.

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