What Is Case Hardening in CNC Machining?

DALIAN, China - Feb. 13, 2022 - PRLog -- What Is Case Hardening?

Case hardening is also called "surface hardening". It is a heat treatment process that hardens the surface of the metal part while keeping the inside of the part relatively soft.

For iron or steel with low carbon content, the case hardening procedure usually involves adding additional carbon or nitrogen to the surface. Solid metals contain molecules and atoms that are tightly packed into a crystalline structure. When carbon diffuses from the carbonaceous material on the surface of low-carbon steel or alloy steel into the crystal structure, the strength and hardness of the outer layer will increase sharply. The shell depth of carbon diffusion can be finely controlled to determine the mechanical properties of the shell.

Why Case Harden?

There are many reasons for surface hardening a material instead of trying to harden an entire metal object. One reason is efficiency. Compared with the entire cross-section of the metal, less energy and time are required to heat the outermost surface of the metal. These efficiencies can save a lot of cost in large-scale manufacturing operations.

Case hardened parts are very suitable for parts that are in constant contact with hard or abrasive parts, because surface hardened parts are more wear-resistant, and they are usually stronger than parts that have undergone the "though-hardening" procedure, because the core of surface hardened parts is soft, so it can Withstand greater stress without cracking. During the surface hardening process, lower temperatures are also applied to various metals (such as thin steel layers) during the manufacturing process to prevent deformation.

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