The development of an improved 2%Cr Mo Ni W V HP/IP rotor material
Current high pressure (HP) and intermediate pressure (IP) steam turbine rotors are normally forged from 1%Cr Mo (Ni) V alloy steels. A steel with physical properties similar to the conventional type but with distinctly higher toughness and at least comparable creep behaviour would offer great advantages. Such a steel has been developed by one steelmaker, Saarstahl, with the composition 2%Cr Mo Ni W V. Within the COST 505 programme, seven European organisations collaborated in an investigation of its properties. They included five turbine generator manufacturers, one forgemaster and one steel research institute. Material from two rotor forgings with diameters of 1,000 and 1,390 mm respectively, manufactured by VCD and ESR routes, was examined for chemical composition, microstructure and heat treatment effects. Appropriate physical properties were measured. The study of mechanical properties covered tensile strength, impact toughness, fracture toughness, low cycle and high cycle fatigue, creep and fatigue crack growth, creep strength and ductility. It was concluded that the 2%Cr Mo Ni W V steel has sufficient high temperature tensile strength together with very good creep resistance and excellent toughness for a creep resistant steel. The fatigue behaviour also compares very favourably with that of the conventional 1%Cr Mo (Ni) V steel for which it can be substituted, particularly where improved toughness is desired.
Bibliographic Reference: EUR 13452 EN (1991) 94 pp., FS, ECU 8.75
ISBN: ISBN 92-826-0595-7
Record Number: 199111140 / Last updated on: 1994-12-02
Original language: en
Available languages: en