Diode laser hardfacing is a welding overlay process that is applied to the material handling component to resist wear and prolong life.
Laser Cladding
Laser Cladding is a process technology that has been in use for 40+ years. Using laser as the heat source, raw metal powder is welded or overlaid on the surface producing a 100% dense metallurgically bonded weld deposit. The advantages of laser cladding are low dilution, low heat input, small heat affected zone, and higher quench rates, which correlates to higher hardness and finer grain structures.
One of the applications for laser cladding is laser cladding of hardfacing materials such as carbides in a metal matrix, also known as laser hardfacing. Laser hardfacing produces impervious overlays tailored for specific wear applications in corrosive or non-corrosive environments. Overlays can consist of iron, nickel, nickel-iron-chrome, or cobalt-base alloys or composites of such alloys and hard particles such as tungsten carbide, chrome carbide and iron carbide. The application for the agriculture, landscaping, construction, and mining industries are obvious but have been cost prohibitive until now. Titanova unique diode laser technology makes laser hardfacing an economic reality.
Laser Hardfacing Technology
The diode laser beam and the hardfacing powder or cored wire material is simultaneously introduced into the laser beam and melted. The diode lasers unique beam enables the welding of a very thin layer of the hardfacing material. The thin layer results in a, low heat input, shallow heat affected zone, and rapid cooling rates. These benefits significantly limit the amount of dilution of base metal but more significantly the disassociation of the hardfacing cermic particles, such as tungsten carbide. As compared with other welding processes with higher heat inputs, for a given hardfacing alloy the fast cooling rate of the laser process produces an overlay with a significantly higher hardness and finer microstructure.
Tungsten Carbide Laser Hardfacing
Tungsten carbide is the standard for high performance hardfacing. A comparison of hardness is shown in the table below. There are several reason, beside hardness that Tungsten carbide is the hardfacing ceramic of choice. It is very chemically stable at molten metal temperatures and not reactive as is the case with diamond [carbon], silicon and titanium. It is has a very high density as compared to silicon carbide, titanium carbide and chrome carbide, which means that it will not float on the molten metal.
