Casedybde

Casedybde is a term used in metallurgy to describe the depth to which a surface-hardening treatment has altered the mechanical properties of a material, typically steel, from the surface inward. In practice, casedybde refers to the distance from the surface at which properties such as hardness, microstructure, or case composition return to the base material values. The concept is central to case hardening processes like carburizing, carbonitriding, nitriding, and induction hardening, which create a hard outer layer while preserving a softer core for toughness.

Measurement and interpretation: Casedybde is usually determined from a cross-section hardness profile or microstructural analysis. Common practice is to identify the depth at which hardness falls below a specified threshold relative to the surface, or where the diffusion gradient becomes negligible. Methods include microhardness testing (Knoop, Vickers) and metallographic examination.

Factors affecting casedybde include alloy content, process temperature and time, furnace atmosphere, cooling method, and subsequent tempering. It can range from a few tens of micrometers for shallow treatments to several millimeters for deep carburizing, depending on material and application.

Applications: A proper casedybde improves wear resistance and surface fatigue life for gears, shafts, cam followers, and other load-bearing parts, while maintaining core toughness. Challenges include achieving uniform depth on complex geometries and controlling distortion.

See also: case hardening, carburizing, case depth, microhardness testing, heat treatment.