The Differences Between Brazing, Soldering, and Welding

Brazing, soldering, and welding are three closely linked methods used to join together pieces of metal. All three methods require heat, thus also requiring safety equipment, meticulously cleaned and maintained tools of the trade, as well as clean metals on which to perform the work.

However, for all their similarities, brazing, soldering, and welding have fundamental differences. Chief among those differences are the levels of heat that are used and the techniques, tools, accessories required, so it is important to be aware of the distinctions.

Q Source is a global distributor of the industry-leading tools and accessories used in brazing, soldering, and welding, so we are uniquely qualified to provide the following overview of each discipline. Continue reading to get a full understanding of which method to use when, and what tools and techniques are most appropriate for the job in front of you.

What is brazing?

Brazing uses a combination of heat, metal filler, and flux to fuse pieces of metal together. Brazing requires optimal temperatures of around 840-degrees Fahrenheit, which is 450-degrees Celsius — higher temperatures than used in soldering and lower than what you’d use in welding, which requires that the metal being joined reach melting temps.

Brazing is often associated with very thin metals such as aluminum, which can be damaged by higher temperatures. Sometimes when working with hard-to-reach joints, brazing is a better option than soldering. Ferrous metals, carbides, and cermets are often best joined through brazing.

Essential tools used for brazing include a torch, furnace, heated chemical bath, or inductor coil for melting the metal filler. A flux solution or filler material is used in brazing, and common filler materials include alkalis, borates, chlorides, fluorides, and fluoroborates. Protective gloves and glasses are also important tools of the trade in brazing.

What is soldering?

The process of soldering joins pieces of metal by using solder — either a solid wire or a pasty flux — and applying it to the metals or pipes to be fused. Only the solder is heated, and soldering requires the lowest temperatures of the three joining methods at below 800-degrees Fahrenheit and 425-degrees Celsius.
Soldering is most commonly used to join electrical contacts, plumbing pipes, and in metalwork using copper, brass, and iron, and to make jewelry using gold and silver. A soldering iron, soldering-iron tip, solder and/or flux are the chief tools of the trade, and tin and zinc alloys, copper, silver, aluminum, and lead are the most commonly used filler metals.
It is also important to use safety glasses and gloves while soldering.

What is welding?

The highest temperatures of the three methods are used in welding, generally above 840-degrees Fahrenheit and 450-degrees Celsius. Unlike either brazing or soldering, welding requires that the metals being joined must reach the melting point to be fused together.

Welding is most commonly used in industrial processes, construction, automotive repair, shipbuilding, and other heavy-duty applications. Different kinds of welding include laser welding, gas welding, plasma arc welding, TIG welding, and MIG welding. Tools of the trade include a welding torch or gun, an electricity source, fuel gas cylinder or oxygen cylinder, and, of course, heavy-duty protective gear on the face, body, and hands.

Welding is not suited to thinner metals like brazing and soldering are, and larger sections of metal can be joined by welding than can with the other two methods. Because of the extremely high temperatures involved and the larger pieces of metal, welding is generally considered more difficult than ether brazing or soldering.