CARBON EQUIVALENT, HARDNESS AND CRACKING TENDENCY RELATIONSHIPS IN C-MN MICROALLOYED STRUCTURAL STEELS

Weldability of new steels, such as microalloyed types produced by the thermomechanical controlled rolling process, is discussed with reference to some major improvements in steelmaking and controlled rolling that have been made in the last decade. In particular, use of low process temperatures and reduced rolling of slabs are well established for producing high grade steel plate. With the introduction of thermomechanical controlled rolling (TMCP), beneficial effects of grain refinement on strength and brittle fracture safety are emphasised, making it possible to lower C content, thereby improving toughness and weldability.