H. Baas et al., THE EFFECT OF OPERATING TEMPERATURE EXPOSURE ON NON-POST-WELD HEAT-TREATED 2.25CR-1MO STEEL WELDMENTS, Canadian metallurgical quarterly, 33(4), 1994, pp. 345-358
Usually a post-weld heat treatment is performed on weld repairs for he
avy section low alloy 2.25Cr-1 Mo steel power plant components. This p
rocedure relieves the stresses in the weldment and results in improvem
ents in both the room and high temperature properties. A significant s
aving, in both time and cost, could be realized if the post-weld heat
treatment could be safely eliminated by an in situ heat treatment or n
on-post-weld heat treatment. In the present work, two different multi-
pass and multi-layer welding procedures were employed and the resultin
g welds were subjected to a simulated in situ heat treatment of 538-de
grees-C for up to 4000 h. The first procedure followed the relatively
standard weaving method of pressure pipe welding, while the second inv
olved a low heat input ratio temper-bead technique. A refined grain st
ructure, within the HAZ was observed for both welding procedures. Afte
r exposure, at the simulated operating temperature of 538-degrees-C, t
here was an initial rapid reduction in hardness and an increase in tou
ghness. Carbide development had a major influence on the mechanical pr
operties. The conventional welding procedure resulted in a higher degr
ee of tempering than the temper-bead weld procedure.