Heat Treatments Vs. Thermochemical treatments

There are two main treatment paths for steel: heat treatments, which transform the internal structure of the material, and thermochemical treatments, which modify only the surface through atomic diffusion.

• Heat treatments involve phase transformations like austenite, martensite, or ferrite, often resulting in distortion. 

• In contrast, thermochemical processes such as plasma nitriding do not alter the core structure. 

• Nitrogen diffuses into the surface, creating hard layers without dimensional change.

In this infographic: a side-by-side comparison of both approaches, their mechanisms, and resulting structures.