TWI Industrial Member Report Summary 404/1989
By R Panton-Kent
Industrial interest is increasing in 9%Cr-1 %Mo steels modified by addition of Nb, V and N, in view of the enhanced creep properties offered relative to standard steels. Work was undertaken to compare the susceptibility to hydrogen cracking of modified and standard 9%Cr-1%Mo steel weld metal. Attention was paid to the effects of varying welding and post-weld heat treatment conditions on the degree of softening in the subcritical heat affected zone (HAZ), and on the final weld area ferrite content.
A series of gapped bead-on-plate tests was carried out on standard and modified 9%Cr-1%Mo manual metal arc (MMA) consumables to evaluate sensitivity to weld metal hydrogen cracking, with pad and bead-on-plate welds produced to assess effects of composition and welding conditions.on joint hardness and microstructure.