Brazing Definitions and examples

Brazing is the oldest metallurgical assembly process, used 4,000 years ago in the age of the Pharaohs to assemble everyday objects (trays, vases) in copper alloy, weapons (dagger handles, swords) and gold ornaments and ornaments. It is now used for technical applications with high added value.

With certain advantages and a few disadvantages, it is often used when dissimilar materials need to be joined together, so that the application benefits from the physical properties of each of the substrates:

• titanium and aluminum alloys for the aerospace industry,

• tungsten carbide with cobalt matrix and C-Mn steel for free-cutting tools,

• copper-alumina alloy for space applications,

• ceramic and stainless steel for nuclear applications.

Brazing can be found everywhere, from jewelry to aerospace, and its mastery can allow it to be used in certain applications where thermomechanical stresses may be on the verge of breaking the base metal.

We will see that brazing involves a number of phenomena:

• anchorages,

• capillary action,

• broadcasting,

• of dissolution.

When the fusion temperature of the filler metal alloy is below 450°C, the term soft soldering is used; above this temperature, the term brazing is used. When the assembly is carried out from close to close while moving the heat source, it's called solder-brazing. Finally, the term diffusion brazing [BM 7 747] is used when diffusion times (from 30 minutes to several hours) at high temperature (but still below the liquidus temperature of the materials) are exacerbated to achieve a mechanical strength close to that of the base substrate.

Transient Liquid Phase (TLP) is an interesting variant of diffusion welding. Like diffusion welding, TLP involves atomic diffusion mechanisms.

The technology chosen for an application will depend on :

• shape and size of parts,

• substrate shade,

• service environment.

This article covers the theoretical aspects of brazing, the main heating...