What process involves heating steel in a carbon-rich atmosphere?

The process of heating steel in a carbon-rich atmosphere is known as case hardening. This technique is specifically designed to enhance the surface hardness of steel components while maintaining a softer and more ductile interior. During case hardening, steel is heated in the presence of a carbon source, often in the form of gases or solid materials, which allows carbon to diffuse into the outer layer of the steel.

As a result of this carbon infusion, the surface of the steel becomes hard and wear-resistant, reaching desirable hardness levels often necessary for components that undergo significant wear during operation, such as gears and shafts. The inner core remains tougher and able to absorb impact without cracking.

In the context of the other processes mentioned, flame hardening is more about localized hardening through direct application of flame. Nitriding involves the introduction of nitrogen to enhance surface hardness, while induction hardening utilizes electromagnetic induction to rapidly heat steel and then quench it for hardening purposes. These methods do not specifically incorporate a carbon-rich atmosphere for the purpose of hardening steel.