9%Cr-1%Mo consumables with small
additions of Nb, V and N, designed
to weld equivalent type 91 for high
integrity structural service at elevated
temperature, especially in power
generation plants and oil refineries
niobium (columbium) and vanadium allow
to provide strength, toughness, fatigue life, oxidation resistance and corrosion resistance at elevated temperatures. Thermal treatment of this alloy is critical and must be closely controlled. The temperature Mf at which the microstructure
has complete transformation into martensite is relatively low; therefore, upon completion of welding and before
post weld heat treatment, it is recommended to allow the weldment to cool to at least 200°F [93°C] to maximize transformation
to martensite.
