Surface layer hardness testing
Surface hardness testing checks the hardness in the outer layer of hardened parts. It's important for quality assurance and avoiding cracks or failures.
Physicochemical mechanism of action
Surface hardness testing measures the hardness of the outer layer of a part that has been hardened by thermal or chemical methods. This layer is harder than the core material and protects it from wear and cracking.
Metallurgical relevance & risks in welding
If the surface hardness is missing or insufficient, the part can be prone to wear and cracking. A hardened layer that is too thin doesn't provide enough protection, while one that is too thick can create high stresses that damage the part.
Workshop practice & instructions
For surface hardness testing, a hardness tester is used. The measurement should be taken on the part surface, not in the weld seam. A typical target is a hardness value of at least 60 HRC for highly stressed parts. If needed, the surface layer can be strengthened by nitriding or induction hardening.