CASE-HARDENED STEEL AND METHOD FOR PRODUCTION THEREOF BY FUSION TREATMENT

摘要

The invention relates to a case hardened steel which comprises, in weight percent, 0.14 to 0.23 % of carbon, 0.2 to 0.4 % of silicon, 0.6 to 1.7 % of manganese, up to 0.035 % of phosphorus, up to 1.5 % of nickel, 0.7 to 1.7 % of chromium, up to 0.5 % of molybdenum, up to 0.04 % of titanium and 0.01 to 0.02 % of nitrogen and other additives conventionally used for steel. The steel also comprises, in weight percent, 0.02 to 0.06 % of niobium, preferably 0.04 to 0.06 % of niobium, and an oxygen content of 40 to 70 ppm and an aluminum content of < 45 ppm and a volume percentage of Nb containing precipitations having an average particle diameter of < 100 nm of > 100 ppm.