Gases for Heat Treatment in Cast Iron and Steel Foundries

The technology involves using industrial gases such as nitrogen, hydrogen, carbon dioxide (CO₂), argon, helium and methanol, instead of generated atmospheres, in heat treatment furnaces to modify the properties of ferrous castings. This offers significant financial benefits for annealing, sintering, brazing, carburising, decarburising, neutral hardening, vacuum backfill, autoclave curing, cryogenic metal treatments and other processing applications in cast iron and steel foundries.Click here for descriptions of these processes.

Air Products supplies PURIFIRE® atmospheres and control panels for metallic heat treatment. The following provides a summary of the advantages of an Air Products industrial gas system over traditional generated atmospheres:

Product Quality - Industrial gas purity can be tailored to meet customers' specific needs. Our high purity gases can increase end-product quality and consistency.

Process Flexibility - With the Air Products control panels, exact amounts of each gas can be blended into the customer's furnace for the particular process and furnace conditions. The atmosphere composition and flow-rate are immediately adjustable to changing production requirements.

Process Reliability - Air Products has a wide rage of supply methods from trucked-in liquid to on-site production of gas. Whichever method suits, our capabilities in production, inventory, and delivery make for reliability of supply of the industrial gas protective atmosphere system. Trucked-in deliveries are coordinated to meet actual requirements.

Safety - All Air Products industrial gas systems are installed to meet all applicable safety codes at both the products storage areas and furnace use points, and nitrogen furnace purging is available. Air Products has a safety record second-to-none in the industrial gas industry.

Efficiency - Industrial gas supply is matched to the process requirement.

Minimal Maintenance - Air Products owns and maintains any on-site gas production equipment, the industrial gas storage vessels and vaporisers. Modifications and maintenance are performed by Air Products' personnel.

Minimal Customer Investment - Customer investment is limited to concrete pads for supply and storage equipment, connecting piping and the necessary blending equipment for the customer's operations.

Heating up and holding at a particular temperature followed by slow cooling, so as to ease cold working, improve machinability, and remove stresses.

Sintering

A process by which loose or compressed metal powders are bonded by heating to a temperature just below the melting point of the constituents.

Brazing

The joining of two metals with a third dissimilar metal, usually copper.

Carburising

The addition of carbon into the surface of a steel by heating and holding at a certain temperature in the presence of a carbon-bearing media, usually CO with methane or propane. This provides a hard wear resistant surface on a tougher core.

Decarburising

The removal of carbon from the surface of steel during heat treatment. Usually used to produce enhanced magnetic permeability.

Neutral Hardening

Heat treatment of steel in an atmosphere that is neither carburising nor decarburising to the metal surface.

Vacuum Backfill / PURIFIRE® Rapid Gas Quench (RGQ®)

The use of inert gases to improve cooling of vacuum furnaces at the end of a heat treatment cycle. Air Products has developed a patented process, known as Rapid Gas Quenching or RGQ®, that maximises the thermal conductivity of the quench atmosphere by blending argon and helium.

Autoclave Curing

Heating of composite materials at pressure to consolidate structure by removing voids and to chemically cure plastic.

Cryogenic Metal Treatment

Rapid cooling of hardened metal using liquid nitrogen to increase maximum hardness and crushing strength.