Patent ID: 8097207

Claim:
Method for reducing the disadvantageous effect of the segregated seams of a steel which has high mechanical strength and high wear resistance and whose composition consists of, in % by weight: 0.30%≦C≦0.93% 0.05%≦Si≦1.5% Mn≦1.95% Ni≦2.9% 1.1%≦Cr≦7.9% 0.61%≦Mo≦4.4% optionally one or more elements selected from vanadium, niobium and tantalum at contents such that V≦1.45%, Nb≦1.45%, Ta≦1.45% and V+Nb/2+Ta/4≦1.45%, optionally up to 0.1% of boron, less than 0.005% of sulphur, optionally up to 0.01% of calcium, optionally up to 0.5% of rare earths, optionally up to 1% of aluminum, optionally up to 1% of copper, the balance being iron and impurities resulting from the production operation, the composition further complying with: 800≦D≦1150 with: D= 540(C) 0.25 )+245(Mo+3 V+1.5 Nb+0.75 Ta) 0.30 +125 Cr 0.20 +15.8 Mn+7.4 Ni+18 Si according to which method: the molybdenum is completely or partially replaced with double the proportion of tungsten so that the content of tungsten is greater than or equal to 0.21%, the contents of titanium and/or zirconium are added such that, if C′ is the content of carbon after adjustment and C is the content of carbon before adjustment: Ti+Zr/2≧0.20×W C′=C+Ti/4+Zr/8 (Ti+Zr/2)×C′≧0.07 and Ti+Zr/2≦1.49%, the precision for carrying out those analytical adjustments at the steel works being such that: 0.95 ×D before adjustment≦ D after adjustment≦1.05 ×D before adjustment, with: D after adjustment=540(C′−Ti/4−Zr/8) 0.25 +245(Mo after adjustment+W/2+3V+1.5Nb+0.75 Ta) 0.30 +125 Cr 0.20 +15.8 Mn+7.4 Ni+18 Si.