Gas carburising is a thermochemical diffusion process used to enhance the surface hardness of ferrous alloys, most commonly low-carbon steels, by introducing carbon into their surface layers. This is achieved by heating components in a carbon-rich gaseous atmosphere at elevated temperatures, typically between 880°C and 980°C, for a specific period, allowing carbon atoms to diffuse into the metal surface.
The depth of carbon diffusion, known as the effective case depth (ECD), depends on time and temperature. It can range from shallow depths of 0.2–1 mm to medium depths of 1–3 mm and even deep case depths of up to 6 mm. After the gas carburising cycle, components are quenched to harden the carburised layer, while the core remains tough and ductile, depending on the steel’s original alloy and carbon content.
Gas carburising is typically performed in a sealed chamber furnace with integrated quenching capabilities. The process consists of the following phases:
Gas carburising is among the most widely used surface hardening methods in modern manufacturing. Due to its reliability, repeatability, and depth control, it accounts for nearly a third of all industrial hardening heat treatments.
Gas carburising is used in industries where long-lasting, impact-resistant components are essential. Typical applications include:
The process is suitable for a wide range of low-carbon and alloy steels, and by adjusting process parameters and alloy composition, manufacturers can precisely balance surface hardness with core toughness.
Gas carburising continues to be a cornerstone of industrial surface hardening, delivering the perfect combination of wear resistance, impact durability, and production flexibility. Its ability to provide deep, controlled case depths with repeatable results makes it indispensable in demanding sectors like automotive, aerospace, and heavy machinery.
As a trusted and proven technology, gas carburising ensures that components are built to last and perform under pressure.
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