Quenching mediums play a crucial role in heat treatment, particularly in a Sealed Quench Furnace (SQF). As the SQF performs carburising, carbonitriding, hardening, and other heat treatment operations within a controlled atmosphere, the choice of quenching medium significantly impacts the mechanical properties and hardness of the treated material. The process involves heating the workpieces to the required temperature in the furnace, which is followed by transferring them to a quenching chamber for cooling.

Importance of Quenching Mediums

The quenching medium in a Sealed Quench Furnace is used to rapidly cool down heated metals and alloys. The quenching medium influences the cooling rate, and additionally, different quenching mediums offer varying cooling characteristics tailored to meet specific requirements of the heat treatment process.

Oil as Quenching Medium

Oil is one of the widely used quenching mediums in a Sealed Quench Furnace due to its moderate cooling rates and the ability to minimise risks. Oil can strike a balance between rapid cooling (offered by water) and slow cooling (offered by gases), making it suitable for a wide range of applications.

Types of Quenching Oils

Polymer as a Quenching Medium

Polymer Quenching Medium is one such medium that offers precise control over cooling rates and is often seen as an effective alternative to traditional oil quenchants. Proper selection of polymer can enhance the heat treatment process by achieving precise control over cooling rates and improving overall surface quality.

Types of Polymer Quenching

Salt as a Quenching Medium

Metals and alloys that use Oil Quenching and Polymer Quenching

Quenching oil and polymer are widely used in heat treatment processes for various metals and alloys to achieve desired mechanical properties.

• Carbon Steels Low, medium, and high-carbon steels often benefit from oil and polymer due to the controlled cooling, helping them achieve uniform hardness and minimised cracking. It is often used for tools, automotive components, and machinery parts.
• Alloy Steels Steels that are alloys require precise control over the cooling rates in order to achieve specific mechanical properties without any distortion. These include Gears, shafts, bearings, and other high-stress components.
• Tool Steels Tool Steels require high hardness and wear resistance which both oil and polymer quenching provide without distortion. These include cutting tools, moulds, dies, etc.
• Stainless Steels Quenching helps stainless steel achieve hardness while reducing the risk of surface oxidation. These include knives, surgical instruments, valves, etc.
• Cast Irons Ductile and malleable iron benefit from quenching to achieve the desired microstructure and mechanical properties. This includes engine components, pipes, and machinery parts.

Considerations for using Oil and Polymer as Quenching mediums in a Sealed Quench Furnace

When selecting a quenching medium in a Sealed Quench Furnace, several factors must be considered to ensure optimal performance, while meeting the requirements of the heat treatment process. Some of the key considerations are-

The choice between Oil and Polymer as a quenching medium depends on various factors such as cooling rate requirements, safety, costs, performance needs, etc. Therefore, careful evaluation of such factors can help select the suitable quenching medium for the Sealed Quench Furnace.