Joining process that melts a filler into a close-fitting joint without melting the parts themselves. The filler's liquidus sits above 450 °C (840 °F), the line between brazing and soldering, but below the solidus of the base metals, and capillary attraction draws the molten alloy through the gap. Heat comes from a torch, induction coil or furnace, often under vacuum or a protective atmosphere, with flux keeping oxide off in open-air work. It joins dissimilar metals and thin parts with little distortion, from HVAC copper to carbide tool tips.
Braze the line set with 15 percent silver rod, heat the fitting, not the rod, and let it pull in.
Heat the heavier part and let the joint melt the filler; melting rod with the flame drips alloy on the outside and leaves the inside dry.
Also heard as
- braze
- hard soldering
Do not mix it up with
- Soldering: Brazing fillers melt above 450 °C and soldering fillers below it; both flow by capillary action without melting the base metal.
Related terms
Soldering
Joining with a filler metal that melts below 450 °C, wetting the parts without melting them.
Joint clearance
The gap between mating parts in a brazed or soldered joint, which controls capillary flow and strength.
Wetting
Molten filler spreading across a clean surface and bonding to it, needed for a sound braze or solder.
Silver solder
Common shop name for silver brazing alloys, even though they melt well above solder temperatures.
Braze welding
Laying a bronze filler in a groove or fillet like a weld bead, without relying on capillary action.