Skip to main content

Heat Treatment

A crucible with hot material inside
page top

Heat Treatment

Heat treatment processes include annealing, hardening, tempering, normalizing, aging, carburizing, and stress relieving. The atmosphere within a furnace chamber is the key to achieving successful, high-precision, repeatable results while preventing oxidation and other undesirable chemical reactions during each process.

The controlled atmospheres used in heat treatment have one of two common purposes: to be chemically inert (or protective) or chemically active (or reactive). An inert, or protective, atmosphere shields the product from unwanted chemical reactions like oxidation and decarburization. Conversely, desirable physical properties can be achieved, such as hardening, by promoting chemical reactions in a reactive atmosphere. In addition to air, gases commonly used to create a controlled furnace atmosphere include hydrogen, nitrogen, oxygen, helium, argon, and carbon dioxide. The first step to establishing an atmosphere is to purge the existing atmosphere from the furnace using the desired gas. For the introduction and removal of gases, the CONCOA 603 Series regulator provides the high-flow purging and process control required to support a controlled furnace atmosphere successfully.

Many controlled-atmosphere furnaces use a flame curtain at the door to contain the atmosphere. When the door is opened, the flame curtain burner activates and covers the door opening with a sheet of flame. This reduces oxygen inrush and maintains internal temperature, while also burning off any combustible gas that may escape while the furnace door is open. Typically, a simple line burner connected to a supply line of compressed air and a relatively high pressure of natural gas or propane (usually 2 PSIG or more) is used. The CONCOA 6790 Series pipeline regulator provides steady and reliable pressure and ensures efficient gas flow control needed to deliver the right air-gas ratio for a flame curtain in a controlled atmosphere furnace.

Safety is a chief concern when working with flammable gases required for heat treatment-related processes. Additionally, gas detection equipment should be employed when using large flows of inert gases. To minimize hazards, CONCOA suggests integrating gas detection and automated safety device equipment. CONCOA oxygen deficiency monitors or dual oxygen/carbon dioxide monitors, installed in gas storage and use areas, provide continuous detection and alert if high concentrations of oxygen-depleting gases should threaten respiration. The 580 Series flammable gas detector provides continuous monitoring of combustible gases and notification before an emergency. Integration with the CONCOA 585 Series emergency shut-off controller ensures the automatic shutdown of up to eight independent gas sources for maximum facility safety.

Browse Related Products