It is important to use materials with low thermal mass so as to achieve the object of heating up the work and not the surrounding refractories. For the bases of forges and furnaces the abrasion resistance of the material needs to be considered if heavy pieces of metal are going to be dragged in and out. The bases may need to be constructed of a dense material to withstand this action.
Forges vs Heat Treatment Furnaces
Forges are generally used for heating metals to make them more mouldable. In other words, the metal is first heated and then hammered into shape.
Heat treatment furnaces use the process of annealing. This involves a cycle of heating and cooling whereby the physical and sometimes the chemical properties of a material are altered to decrease hardness and make the material more workable.
You can find more information on our blog article on How to make a Forge
For materials with low thermal mass, we recommend using Ceramic Fibre Blanket, Ceramic Fibre Board or Insulation Bricks (grade 23 at 1260°C or grade 26 at 1430°C). The insulation bricks should be laid with White Refractory Mortar, unless the setup is very simple for welding or brazing, then mortar may not be necessary at all. For adhering the ceramic fibre blanket or board to the metal structure, use Ceramic Fibre Adhesive. For coating the ceramic fibre, use Zircon Paint Coating to give a protective, hard outer shell with higher temperature resistance (up to 1750°C) than that of the ceramic fibre.
To prevent abrasion in vulnerable areas, use a dense refractory like our Refractory Castable such as the one graded up to 1400oC or our dense Fire Bricks with 40% or 42% alumina content. If there is a blast pipe in the traditional coke fired forges, we recommend using our Mouldable Firebrick around the pipe. This material gradually sets hard with the heat.