What surface treatment is primarily used to improve wear resistance by hardening the surface of steel components?

The correct response, which is case hardening, involves a set of processes designed to harden only the surface layer of a steel component, significantly enhancing its wear resistance while maintaining a tough and ductile core. This is crucial in applications where components experience substantial surface wear due to friction and contact, such as gears, shafts, and bearing surfaces.

Case hardening typically involves processes like carburizing or nitriding, where carbon or nitrogen is introduced into the surface layer of the steel at high temperatures. This results in a hard outer layer while preserving the softer properties of the inner material, allowing for a balance of both toughness and hardness. The increased hardness at the surface, combined with the toughness of the core, is particularly beneficial for applications requiring resilience to wear and fatigue.

Other options, while related to the treatment of steel, do not specifically introduce this dual-property effect. Cementation, for example, is similar to case hardening but may be less commonly referred to in broader terms. Forging is primarily a process of shaping metal through heat and deformation rather than a treatment designed to improve surface hardness. Hardening generally refers to processes that increase the hardness of the material throughout rather than just at the surface. Thus, case hardening stands out as the most