Strength on carbon content

The factors determining the strength and weldability in carbon steel are mainly carbon content. Alloy steels (mainly low-alloy steels) in addition to carbon also play an important role in the strength and weldability of steel. In order to facilitate the expression of the strength properties and weldability of these materials, the statistics of a large amount of test data are simply expressed in terms of carbon equivalent. There are many carbon equivalent indicators such as tensile strength carbon equivalent, yield strength carbon equivalent, weld carbon equivalent, and crack sensitivity index (substantially also carbon equivalent).

The conceptual sources of carbon equivalents, as well as theoretical applications, are closely related to the iron-carbon phase diagram. By comparing the carbon content of CE with the eutectic point, the direction and extent of the specific composition cast iron deviating from the eutectic point can be determined. It can be easily judged whether the composition is hypereutectic, hypoeutectic or eutectic.