You need to provide more information in order to get the answer you are looking for. Are these racks going to be used again and again to hold parts in a heat treating furnace? If that is the case then you need to provide more details about the type of furnace they will be used in, the temperature range that they are likely to see, and the furnace atmosphere that they will be exposed to. For example, if you will be using these racks in a case carburizing furnace atmosphere, you will probably want to use either 330 stainless steel or Inconel in their construction. If these are racks that you are heat treating only once for use in some other application, then no-carb paint might do the job. You can find it here:

http://heatbath.com/heat-treating-products-2/stop-...

Maui

I am looking for an alternative to buying a different material. We can cast the racks here in a low alloy carbon steel. I am looking for a coating that can be Austenitized in a slightly oxidizing atmosphere and then quenched in water. Basically, my intention is to increase the life of the racks by reducing the amount of scaling by coating the rack.

You need to provide a temperature range of operation. Any coating that you would apply will very likely have a different thermal expansion coefficient than the base material. Using typical austinitizing temperatures that exceed 1500F will produce large thermal gradients during water quenching and the resulting stresses at the boundary between the base material and the coating will very likely compromise the adhesion of the coating to the surface.

Maui