Carbon Equivalent according to International Institute of Welding
The carbon equivalent (CE) is a value used to estimate the cold cracking tendency of unalloyed and low-alloy steels. It takes into account the percentage content of carbon, silicon, chromium, molybdenum, and niobium. A high CE value leads to greater hardness and increases the susceptibility to cold cracking.
Physical-Chemical Mechanism
The carbon equivalent (CE) is calculated based on the percentage content of carbon, silicon, chromium, molybdenum, and niobium. These elements influence the microstructure and hardness of the steel. A high CE value leads to greater hardness and increases the susceptibility to cold cracking.
Metallurgical Relevance & Welding Risks
A carbon equivalent that is too high can cause cold cracking, especially in the heat-affected zone. This can lead to cracks and distortion in the welded joint. Additionally, the material becomes harder, making welding and machining more difficult.
Workshop Practice & Instructions
To avoid cold cracking, the CE value for the welded joint should be below 0.75%. If the value is higher, special treatment or a different material is required. Make sure the weld cools slowly and the microstructure does not become too hard.