Forged steel composition used in the production of crankshafts for ships includes silicon, manganese, chromium and molybdenum

摘要

Forged steel composition contains (in wt.%): 0.3-0.5 carbon, 0.1-0.4 silicon, 0.7-1.5 manganese, 1.2-3.5 chromium, 0.1-0.6 molybdenum, not more than 0.7 nickel, 0.03-0.35 V, Nb and/or Ta, 30-250 ppm nitrogen, and a balance of iron. The steel forms a microstructure consisting of bainite and martensite and contains nitrogen in solid solution with V, Nb and Ta in such that (total wt.% of V, Nb and Ta) + 0.001 x (N (ppm) in solid solution) /- 0.068. Preferred Features: The steel contains (in wt.%): 0.36-0.45 carbon, 0.15-0.4 silicon, 0.8-1.2 manganese, 1.5-3.0 chromium, 0.15-0.35 molybdenum, 0.17-0.35 V. The steel further contains 0.001-0.10 aluminum and not more than 0.006 wt.% sulfur.