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Welding & Joining Technology: Brazing, Braze Welding, and Soldering.

This Libguide will help students in the welding program learn about welding fundamentals and process



EBooks from Galileo


Soldering Guide 

Guide to soldering


How to Solder 

soldering tutorial


Braze Welding 

Guide to Braze Welding


Brazing Process Fundamentals: How to Braze in Six Steps 

Guide to brazing


Handbook on Braze welding 

Guide to Brazing, Braze welding, materials, and soldering


Gas Brazing

Aluminum Brazing



Brazing, Braze Welding, and Soldering


Brazing, Braze Welding, and Soldering


Brazing joins two metals by heating and melting a filler (alloy) that bonds to the two pieces of metal and joins them. Brazing can join dissimilar metals such as aluminum, silver, copper, gold, and nickel. 

Soldering is a low-temperature analog to brazing. By the American Welding Society’s definition, soldering takes place with fillers (also known as solders) that melt at below 840°F (450°C). Metals that can be soldered include gold, silver, copper, brass, and iron. The filler melts. When it solidifies, it is bonded to the metal parts and joins them.

Braze welding is the use of a bronze or brass filler rod coated with flux to join steel workpieces. 



Terminology in Brazing and Soldering

The phase is the temperature at which bonding takes place between the solid base material and the liquid filler metal

Capillary action is the force that pulls water up into a paper towel or pulls a liquid into a very fine straw

Tensile strength of a joint is its ability to withstand being pulled apart

Shear strength of a joint is its ability to withstand a force parallel to the joint

Ductility of a joint is its ability to bend without failing

Fatigue resistance of a metal is its ability to be bent repeatedly without exceeding its elastic limit and without failure

Corrosion resistance of a joint is its ability to resist chemical attack

 A paste range is the temperature range in which a metal is partly solid and partly liquid as it is heated or cooled. 

Brazing temperature is the temperature to which the base metal is heated to enable the filler metal to wet the base metal and form a brazed joint.


Fluxes used in brazing and soldering have three major functions:

● They must remove any oxides that form as a result of heating the parts.

● They must promote wetting, which is the phenomenon whereby a liquid filler metal or flux spreads and adheres in a thin, continuous layer on a solid base metal. In soldering the process is often called tinning.

● They should aid in capillary action by pulling the molten alloy into the joint. 


Fluxes are available in many forms, such as solids, powders, pastes, liquids, sheets, rings, and washers. They are also available mixed with the filler metal, inside the filler metal, or on the outside of the filler metal

Brazing and soldering fluxes will remove light surface oxides, promote wetting, and aid in capillary action. Fluxes will not remove oil, dirt, paint, glues, heavy oxide layers, or other surface contaminants.

Soldering fluxes are chemical compounds such as muriatic acid (dilute hydrochloric acid), sal ammoniac (ammonium chloride), or rosin. Brazing fluxes are chemical compounds such as fluorides, chlorides, boric acids, and alkalies.

These compounds react to dissolve, absorb, or mechanically break up thin surface oxides that are formed as the parts are being heated.

Brazing and Soldering Methods

Torch Brazing and Soldering:

  • torch brazing (TB): A brazing process that uses heat from a fuel-gas flame. 
  • torch soldering (TS): A soldering process that uses heat from a fuel-gas flame. 

Furnace Brazing and Soldering:

  • furnace soldering (FS): A soldering process using heat from a furnace or oven
  • Furnace Brazing (FB): A brazing process in which assemblies are heated to the brazing temperature in a furnace. 

Induction Brazing and Soldering 

  • induction brazing (IB): A brazing process using heat from the resistance of the assembly to induced electric current
  • induction soldering (IS): A soldering process in which the heat required is obtained from the resistance of the workpieces to induced electric current. 

Dip Brazing and Soldering:

  • dip brazing (DB): A brazing process that uses heat from a molten salt bath or a metal. When using the molten salt bath may act as flux. When using the molten metal, the bath provides the filler metal. 
  • dip soldering (DS): A soldering process using the heat, oil, or salt bath in which it is immersed. 

Resistance Brazing and Soldering

  • resistance brazing (RB): A brazing process using heat from the resistance to electric current flow in a circuit that includes 
     the assembly.
  • resistance soldering (RS): A soldering process that uses heat from the resistance to electric current flow in a circuit of which the workpieces are a part.