Pintakarkaisumenetelmä

Pintakarkaisumenetelmä, also known as surface hardening or case hardening, is a heat treatment process used to improve the surface hardness of steel parts while maintaining a tough and ductile core. This method is crucial for components that experience high wear and abrasion, such as gears, bearings, and cutting tools. The primary goal is to create a hardened surface layer, or "case," which is significantly harder than the underlying material.

Several techniques fall under the umbrella of pintakarkaisumenetelmä. Carburizing is a common method where steel is heated in a carbon-rich atmosphere, causing carbon atoms to diffuse into the surface. Subsequent quenching and tempering then produce the hardened case. Nitriding involves introducing nitrogen to the steel surface, often at lower temperatures than carburizing, resulting in a very hard and wear-resistant layer, particularly effective against scuffing. Carbonitriding combines elements of both carburizing and nitriding. Flame hardening and induction hardening are surface hardening methods that rapidly heat a localized area of the steel surface to a critical temperature, followed by immediate quenching.

The depth of the hardened case, its hardness, and the overall metallurgical structure are controlled by factors such as the specific process used, the base material's composition, temperature, time, and the quenching medium. Pintakarkaisumenetelmä allows for the creation of components with a desirable combination of surface properties for wear resistance and core properties for toughness and shock absorption, extending the service life of critical machinery parts.