Welding Tungsten Carbide

 From the book Building Superior Brazed Tools  Buy the Book 

Weldable tungsten carbide is generally used to mean the joining of tungsten carbide to steel without the use of braze alloy.  Welding tungsten carbide may or may not be true welding. 

This is achieved by using tungsten carbide parts such as saw tips that have a special surface enhancement.  A tungsten carbide saw tip with a large amount of surface cobalt can be induction “welded” reliably and easily.  There is a great saving in the cost of brazing alloy and the cost of pretin.   

In welding tungsten carbide there are two parts.  The steel saw body and the prepared tungsten carbide saw tip.  The prepared tip has a surface prepared with something such as cobalt. This pure cobalt surface is fairly magnetically responsive.  The steel heats up fastest but the tip also heats up as well.  The difference here is the amount of heat transference from the steel to the tip.  The steel then flows onto and around the tungsten carbide part.  The steel alloys with the cobalt on the surface.  It forms a very strong bond. 

There are several problems.  Braze alloy does more than join parts.  It also acts as a shock absorber to keep the part from breaking.  Brazing is also a better technology for the production of custom saws in limited quantities. 

Welding tungsten carbide is used two ways.  It is used in the production of inexpensive tungsten carbide tipped, circular saws for the handyman market.  It is also used to make tungsten carbide tipped band saws. 

Please do not confuse these products with the really cheap “tungsten carbide” tipped blades.  There have been saw blades sold as “tungsten carbide tipped” there were really steel tipped.  The labeling explained in small print that the tip material was well over 90% iron and did have some tungsten carbides included that formed naturally as part of the welding process.  This is true but not what is generally meant by “tungsten carbide” in this application.