When it comes to joining two metals, there are very few options to create a solid joint that will hold throughout the desired use and application. One is welding, and the other option is brazing. Steel brazing is particularly important when the alloys are stainless steel, or if there is a need to braze steel to copper or another base metal.
Welding is very different than steel brazing, although the both use heat. With welding, the joint is made by actually melting the two metals on either side of the joint together with the use of a filler metal. Steel can be welded using several methods, including MIG welding, but it doesn’t offer the benefits of steel brazing that are so important for parts and components.
What is Brazing?
Unlike welding, steel brazing doesn’t actually melt the steel or the other metal. Instead, a filler metal is used that is drawn into the joint through capillary action, forming a seal that is perfect and free from the inconsistencies that can occur with welding or with soldering.
In fact, the joint itself is actually stronger than either of the base metals when the process of steel brazing is done correctly and there is the right choice in the filler metal.
The Importance of Clearance
With the need for capillary action to draw the molten filler metal into the joint, the two different metals on either side of the joint have to have clearance. In other words, there has to be a specific space or clearance between the two for steel brazing.
This clearance is a critical factor in allowing the formation of a solid, complete joint. This is why designing the component and understanding the thickness of the components and the optimal clearance is an essential part of the process before the brazing actually starts.
Optimizing the Braze
With the very comprehensive and complete joint available from steel brazing, the need for all contaminants and surface imperfection to be removed before the process is critical.
Taking the time to clean both surfaces and also to apply flux, or the compound that will prevent oxides from forming where the joint needs to develop during heating, is another critical step.
Depending on the size of the component for the steel brazing dipping the entire component in flux may be an option, and this is also common with large production types of brazing with small parts and components.