Carbon steels consist mainly of iron-carbon alloys with limited amounts of other elements like manganese and silicon, which serve generally as deoxidizing elements, along with traces of residual or undesirable elements such as sulphur and phosphorus. Carbon steels are categorized according to carbon content, as follow :

  • Mild steels or low-carbon steels (C ˂0,20%), used for general construction, pipes, tanks, farm equipment, etc. ;
  • Medium-carbon steels (0,30-0,50% C), commonly used for mechanical parts such as gears, shafts, etc.;
  • High-carbon steels (0.60-0.80% C), used for saw blades, railroad tracks, etc. 

The carbon content or the carbon equivalent (CEQV), which takes into account the effect of the other alloying elements, determines and influences the weldability of the steel. As the CEQV increases, the weldability decreases. Beginning at a carbon equivalent of 0.45%, the steel must be preheated prior to welding in order to prevent hardening and embrittlement in the heat-affected zone.

Contact our metallurgists, to get the right alloy for your welding project.