Heat treating comprises a variety of industrial processes used to alter the physical and sometimes chemical properties of a material. The most common of these processes is metallurgy. Heat treating involves the use of heating or chilling to achieve a desired result such as hardening or softening of a material. Heat treatment techniques include annealing, nitriding, stress relieving, forging, tempering, normalizing, and quenching. Both ferrous and non-ferrous metals are treated.
There are many furnace types used in heat treating, the most common types being car bottom furnaces, roller hearth furnaces, bell furnaces, batch and continuous furnaces, and rotary hearth furnaces.
Refractory selection varies widely for these furnaces and is dependent on the furnace process. Typical linings can use fired brick products chosen for their properties and resistance to furnace operating conditions. UFALA® may be used in furnace environments where the refractory needs to be resistant to carbon monoxide because it has the ideal low-iron chemistry for this environment. GREENTHERM insulating firebricks are suited for backup linings behind dense brick, providing strength and insulating value. For large heat treat furnaces with car decks, select coarse aggregate castables like VERSAFLOW® 45 C PLUS for the strengths and cycling resistance, with the coarse aggregate castable having excellent impact resistance for the loads applied to the car deck. INSWOOL® ceramic fiber products like INSWOOL® modules provide low thermal conductivity, low heat storage, excellent thermal-shock resistance, and good high-temperature stability. They are available in a wide temperature range, from 1500°F to 3000°F, and are often used in annealing furnaces.