Abstract: An abrasion-resistant steel consists essentially of 0.05 to 0.45 wt. % C, 0.1 to 1 wt. % Si, 0.1 to 2 wt. % Mn, 0.05 to 2 wt. % Nb and the balance being Fe and inevitable impurities, the steel includes at least 200 of precipitates of 15 .mu.m or more in particle size per 1 mm.sup.2 and the precipitates contains Nb.In addition to the above basic elements, at least one element selected from the group consisting of 0.1 to 2 wt. % Cu, 0.1 to 10 wt. % Ni, 0.1 to 3 wt. % Cr, 0.1 to 3 wt. % Mo and 0.0003 to 0.01 wt. % B or at least one element selected from the group consisting of 0.003 to 0.05 wt. % Ti and 0.01 to 1 wt. % V is added to steel.

Abstract: An abrasion-resistant steel having excellent surface property consists essentially of 0.1 to 0.45 wt. % C, 0.1 to 1 wt. % Si, 0.1 to 2 wt. % Mn, 0.04 wt. % or less P, 0.04 wt. % or less S, 0.1 to 1 wt. % Ti, 0.0015 to 0.01 wt. % N, and the balance being Fe and inevitable impurities, the steel including at least 400 TiC precipitates of 0.5 .mu.m or more in particle size per 1 mm.sup.2 and the steel having Ti* of 0.05 wt. % or more and less than 0.4 wt. % the Ti* being defined by the equations of Ti*=Ti(a)-[Ti], Ti(a)=Ti-{(48/14)N+(48/32)S}, log[Ti][C]=(-10580/T)+4.38, [Ti]=4.times.[C]+{Ti(a) -4.times.C}.A method for producing an abrasion-resistant steel having excellent surface property comprising the steps of: preparing a molten steel having the composition specified above; casting continuously the molten steel to produce slab, coarse particles of TiC being precipitated in the slab; hot-working the slab to produce a hot-rolled steel sheet at 1300.degree. C. or less; and quenching the hot-rolled steel sheet.

Abstract: An abrasion-resistant steel consists essentially of 0.05 to 0.45 wt. % C, 0.1 to 1 wt. % Si, 0.1 to 2 wt. % Mn, 0.05 to 1.5 wt. % Ti and the balance being Fe and inevitable impurities, the steel includes at least 200 of precipitates of 1 .mu.m or more in particle size per 1 mm.sup.2 and the precipitates contains Ti.In addition to the above basic elements, at least one element selected from the group consisting of 0.1 to 2 wt. % Cu, 0.1 to 10 wt. % Ni, 0.1 to 3 wt. % Cr, 0.1 to 3 wt. % Mo and 0.0003 to 0.01 wt. % B is added to steel or at least one element selected from the group consisting of 0.005 to 1 wt. % Nb and 0.01 to 1 wt. % V is added to steel.

Abstract: An abrasion resistant steel consisting essentially of 0.05 to 0.45 wt. % C, 0.1 to 1 wt. % Si, 0.1 to 2 wt. % Mn, 0.3 to 1.5 wt. % Ti, at most 0.005 wt. % N and the balance Fe as the basic elements contributing to the enhancement of the abrasion resistance property, without excessively increasing the hardness of the steel. In addition to the basic elements, at least one element selected from the group consisting of 0.1 to 2 wt. % Cu, 0.1 to 10 wt. % Ni, 0.1 to 3 wt. % Cr, 0.1 to 3 wt. % Mo and 0.0003 to 0.01 wt. % B may be added to enhance the quenching hardenability of the steel, and 0.01 to 0.5 wt. % V may be added to enhance the precipitation hardenability of the steel.

Abstract: A method and an apparatus for cooling a steel sheet, which comprises: ejecting cooling water onto a steel sheet laid horizontally from above and from below said steel sheet immediately after the completion of hot rolling to cool said steel sheet; shielding each of the both side edge portions of the upper surface in the width direction of said steel sheet from said ejected cooling water by a shielding means movable in the width direction of said steel sheet so that the temperature distribution in the width direction of said steel sheet becomes uniform at the completion of the ejection of cooling water; and, determining a shielding width of each of said both side edge portions of said steel sheet, which is shielded from said ejected cooling water, on the basis of the width and the thickness of said steel sheet, the temperature and the flow rate per unit area of cooling water ejected onto the upper and the lower surfaces of said steel sheet, the period of time from start to completion of the ejection of cooling

Abstract: A method for forcedly cooling a heated metal plate, which comprises: moving a heated metal plate horizontally in the longitudinal direction of said metal plate at a prescribed speed through a cooling equipment comprising a plurality of rows of nozzles arranged at prescribed intervals in the width direction of said metal plate above and below said metal plate; and spraying a cooling liquid from said nozzles onto the upper and lower surfaces of said metal plate during moving of said metal plate through said cooling equipment to cool said metal plate to a prescribed temperature.