Weld HAZ embrittlement of Nb containing C-Mn steels

摘要

The adverse influence of Nb on weld HAZ properties is still an active issue of discussion betweenconstruction companies and steel manufacturers. Some controversy exists in the literatureconcerning the influence of Nb on HAZ properties under certain conditions, and this investigationwas subsequently performed over a range of C and Nb compositions, typical of the steels concerned,and for three different single cycle heat inputs ranging from 1.5 to 6 kJ/mm. Simulated thermal cycleswere employed, using a Gleeble 1500 thermomechanical simulator, followed by CVN testing. It isshown that Nb additions can have a detrimental or beneficial effect at low heat inputs, depending onthe C level, but a severe detrimental effect of Nb on RAZ toughness is observed at high heat inputs andC levels.