Surface carbon content
Edge carbon content indicates how much carbon is present in the outer layer of a hardened steel. Too high a content can lead to crack-sensitive martensite and thus to hot cracks.
Physical-Chemical Mechanism
Surface carbon content describes the carbon concentration in the outer layer of a steel after the hardening process. With an increased carbon content, martensite can form during cooling, which can lead to high stress states and possible cracking.
Metallurgical Relevance & Welding Risks
A high surface carbon content increases the risk of hot cracking and a glass-hard structure. This can lead to component failure and potential breakdowns. It is important to closely control the carbon content during cooling.
Workshop Practice & Actions
To minimize the risk of hot cracking, the surface carbon content should be measured and controlled after the hardening process. If the level is too high, retreatment or adjustment of the process may be required. A carbon content of max. 0.4% in the outer layer is recommended.