Welding, Brazing, & Soldering

As a welder, I have heard many people confuse the process that I use in my trade with other similar methods of joining metal materials. Some may think that the all the processes do the same thing, but actually they do not. The three basic types of methods to join metal materials are welding, brazing and soldering.

Welding melts the metals at the joint using very high temperatures. Essentially the metal from the two parts is blended by heat. However, if the metal melts too easily it will become a liquid and run out of the weld area. Properly executed, a weld is just as strong as the metal being joined. However, the higher heat of welding can change the material properties if you aren't careful. This change in the metal's properties can make the weld weak. Therefore, welds are commonly performed on like materials only.

Brazing uses a braze alloy that become liquid at a moderate temperature to join two other metals. These metals can be the same or dissimilar. The joined materials are NOT molten as they are in welding, but the braze alloy is liquid and flows between the joint. Properly performed brazed joints can possibly be stronger than the work pieces they joined. Unlike welding, brazing only has minimal impact on material properties. Braze alloys can also be expensive. Copper alloys are commonly brazed, particularly since copper's properties make it very difficult to weld.

Soldering uses an alloy that is liquid at relatively low temperatures to join two other metals. It has the least impact on the base materials, and also provides the weakest joint. It is particularly useful when heat can damage or distort the materials being joined. Electrical components are commonly soldered to avoid heat damage. This method is more delicate than that of the other two described here. Various metals can be soldered together, such as gold and sterling silver in jewelry, brass in watches and clocks, copper in water pipes, or iron in leaded glass stained windows.

I hope that this has cleared up any misconceptions you may have had about welding, brazing and soldering. As you can tell, these processes differ greatly but many who work with metal fabricating may use a little bit of each of the methods in their line of work. Now you can go impress your friends with your new found knowledge of the joining of metals!