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Abstract

The invention concerns a method for making an abrasion resistant steel plate having a chemical composition comprising: 0.35%.ltoreq.C.ltoreq.0.8%, 0%.ltoreq.Si.ltoreq.2%, 0%.ltoreq.Al.ltoreq.2%, 0.35%.ltoreq.Si+Al.ltoreq.2%, 0%.ltoreq.Mn.ltoreq.2.5%, 0%.ltoreq.Ni.ltoreq.5%, 0%.ltoreq.Cr.ltoreq.5%, 0%.ltoreq.Mo.ltoreq.0.50%, 0%.ltoreq.W.ltoreq.1.00%, 0.1%.ltoreq.Mo+W/2.ltoreq.0.50%, 0%.ltoreq.B.ltoreq.0.02%, 0%.ltoreq.Ti.ltoreq.2%, 0%.ltoreq.Zr.ltoreq.4%, 0.05%.ltoreq.Ti+Zr/2.ltoreq.2%, 0%.ltoreq.S.ltoreq.0.15%, N.ltoreq.0.03%; optionally from 0% to 1.5% of Cu; optionally Nb, Ta or V with Nb/2+Ta/4+V.ltoreq.0.5%; optionally less than 0.1% of Se, Te, Ca, Bi or Pb; the rest being iron and impurities; the composition satisfying: 0.1%.ltoreq.C*=C-Ti/4-Zr/8+7.times.N/8.ltoreq.0.55% and 1.05.times.Mn+0.54.times.Ni+0.5O.times.Cr+0.3.times.(Mo+W/2).sup.1/2+K>-;1.8, with K=0.5 if B.gtoreq.0.0005% and K=0 if B<0.0005% and Ti+Zr/2-7.times.N/2.gtoreq.0.05%; hardening after austenitization while cooling at a speed >0.5.degree. C/s between a temperature >AC.sub.3 and ranging between T=800-270.times.C*-90.times.Mn-37.times.Ni-70.times.Cr-83.times.(Mo+W/2) and T-50.degree. C.; then at a core speed Vr<115.times.ep.sup.-1.7 between T and 100.degree. C., (ep=plate thickness in mm); cooling down to room temperature. The invention also concerns the resulting plate.

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First Claim