Steel alloy designs for control of weld heat affected zone properties

This paper reviews the current technology related to the control of weld HAZ properties in high strength steels. The debate related to the appropriate balance of Ti and N is addressed and it is concluded that a stoichiometric ratio provides optimum fracture toughness. Although the control of the Ti/N ratio is difficult, this paper now provides guidance in terms of alloy design to achieve optimum fracture toughness in the HAZ. The enhanced resistance to grain coarsening behaviour in higher Nb steels has now provided another incremental improvement in the weldability of these steels for critical applications, such as high pressure gas transmission pipelines. The role of Mo in the alloy design of these new steels is a further activity to be undertaken in the design concept to further improve the performance and safety of modern steel structures. (AU) © 2015 Companhia Brasileira de Metalurgia e Mineração (CBMM)