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Abstract

The invention refers to a method for producing a molten steel having high wear resistance having a mainly bainitic microstructure and a suitable balance of tensile strength and hardness for pieces of large size in mining operations such as milling and grinding, the chemical composition of which, expressed in weight percentage, comprises: 0.30-0.40% of C, 0.50-1.30% of Si, 0.60-1.40% of Mn, 2.30-3.20% of Cr, 0.0-1.00% of Ni, 0.25-0.70% of Mo, 0.0-0.50% of Cu, 0.0-0.10% of A, 0.0-0.10% of Ti, 0.0-0.10% of Zr, less than 0.050% of P, less than 0.050% of S, less than 0.030% of N, optionally less than 0.050% of Nb, optionally 0.0005-0.005% of B, optionally 0.015-0.080% of rare earth metals, and residual contents of W, V, Sn, Sb, Pb and Zn of less than 0.020%, and the balance in iron. The method for producing the molten steel includes smelting and heat treatment. The smelting can be carried out in an electric arc furnace having basic or acid refractory or an electric induction furnace. Smelting in an electric arc furnace as a normal operation includes melting, oxygen insufflation, blocking, refining and deoxidation. Smelting in an electric induction furnace includes melting, refining, control of nitrogen in solution and deoxidation. Heat treatment comprises settling and tempering. The molten steel described in the invention exhibits a suitable balance of the chemical composition, tensile strength and hardenability to assure complete hardening in cast pieces of large size, typically up to 17 inches in thickness, with Brinell hardness preferably in the range of 385-495 BHN throughout the section of the piece and excellent resistance to wear by abrasion impact.

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First Claim