When Brazing Beats Welding

Brazing is an economical method for making strong, permanent metal joints. Compared with welding, brazing requires relatively low temperatures, is readily automated, and can join dissimilar metals. Brazing filler materials come in a wide range of compositions, shapes, and sizes to suit most applications. There are a number of options when it comes to joining metal parts, including adhesive bonding, nuts and bolts, and many other types of mechanical fasteners. But for strong and permanent metal joints, the choice usually comes down to either welding or brazing. Welding joins metals by melting and fusing them, usually adding a filler material. Fusion requires concentrated heat directly at the joint, and temperatures must exceed the melting point of the metals and filler. Welded joints are usually as strong or stronger than the base materials. Brazing differs from welding in that the temperature is considerably lower and does not melt the base metals. Rather, the heat source melts a filler metal and draws it into the joint by capillary action. It creates a metallurgical bond between the filler metal and part surfaces. Like welding, joint strength often exceeds that of the individual parts. For instance, the tensile strength of stainlesssteeljoints can exceed 130,000 psi. But because brazing temperatures are lower, generally 1,150 to 1,600°F, most physical properties remain unaffected. Distortion and warping are minimal, and it minimizes stresses in the joint area. Lower temperatures also