Large steel forging - of high strength,ductility and machinability

摘要

The steel contains 0.1% max. C, 0.5% max. Si, 0.7% max. Mn, 5-13% Cr, 2-10% Ni, 1.5-5% Mo and/or W and 3-8% C. The delta ferrite concn. (%) = -146-220 (C% + N%)-20 (Ni%)-7(Co%)-6(Mn%) + 6(Si%) + 5 (Mo%) + 14 (Cr%) + 8 (W%) = -80 to -200. The Ms point (degrees C) = 554-474 (C% + N%) - 17 (Ni%)-10(Co%) -33(Mn%) -11 (Si%) -21(Mo%) -17(Cr%) -11(W%) 100. After forging the steel undergoes long-term cooling from 750-1050 degrees C to is not 400 degrees C and a 3-500 hr. ageing at 450-550 degrees C.