Vergütungsstähle

Vergütungsstähle, also known as case hardening steels or surface hardening steels, are a category of low-carbon alloy steels designed for through hardening in the core and selective surface hardening. Their primary characteristic is the ability to achieve a hard, wear-resistant surface while maintaining a tough, ductile core. This is accomplished through a heat treatment process called case hardening, which typically involves carburizing or carbonitriding followed by quenching and tempering.

The low carbon content, usually between 0.1% and 0.25%, in the core allows for significant deformation during quenching without fracturing, ensuring toughness. Alloying elements such as chromium, nickel, molybdenum, and manganese are added to improve hardenability, strength, toughness, and resistance to tempering. These elements also refine the grain structure and enhance the depth of hardening.

The surface hardening process introduces carbon into the outer layer of the steel at elevated temperatures, creating a high-carbon case. Upon rapid cooling (quenching), this case transforms into a hard martensitic structure, providing excellent wear resistance and hardness. The core, with its lower carbon content, remains softer and more ductile, absorbing shocks and preventing brittle fracture.

Vergütungsstähle are widely used in applications requiring a combination of high surface hardness and core toughness. Common examples include gears, camshafts, crankshafts, bearings, pinions, and other components subjected to significant wear, fatigue, and impact loads in automotive, machine tool, and general engineering industries. The specific alloy composition and heat treatment parameters are critical in achieving the desired properties for each application.