The Hardness subnode is used to compute the Vickers hardness (HV) and the Rockwell C hardness (HRC) of steel, after cooling from an austenitic state. One or several Hardness subnodes can be added to a Steel Composition node. In the Hardness subnode, you select the metallurgical phases that represent, respectively, ferrite, pearlite, bainite, and martensite. Based on this information, the chemical composition of the steel defined in the parent Steel Composition node, and certain characteristics of the cooling transient, the hardness is computed.