Carbon equivalent

Carbon Equivalent is a measure used in metallurgy to quantify the combined effect of different alloying elements used in the production of steel. It provides a numerical value that represents the overall effect of these elements on the steel's ability to be welded and its susceptibility to cold cracking.

Definition

The Carbon Equivalent (CE) is calculated using the formula:

CE = C + Mn/6 + (Cr + Mo + V)/5 + (Ni + Cu)/15

where C, Mn, Cr, Mo, V, Ni, and Cu represent the weights of the respective elements.

Use in Metallurgy

In metallurgy, the carbon equivalent is a useful measure for determining the weldability of a particular type of steel. Steels with a high carbon equivalent are more likely to suffer from hydrogen-induced cracking after welding.

Factors Influencing Carbon Equivalent

Several factors can influence the carbon equivalent of a steel, including the heat treatment it undergoes, the cooling rate, and the presence of residual stresses. The carbon equivalent can also be affected by the presence of certain elements, such as sulfur and phosphorus, which can increase the steel's susceptibility to cracking.

Limitations

While the carbon equivalent is a useful measure, it has its limitations. It does not take into account the effect of nitrogen in steel, which can also contribute to cracking. Furthermore, it does not consider the effect of the welding process itself, which can introduce additional stresses and defects into the steel.

See Also

• Weldability
• Hydrogen-induced cracking
• Metallurgy