BAINITIE-BASE RAIL WITH LOW ELECTRIC RESISTANCE, EXCELLENT IN WELDED JOINT CHARACTERISTIC AND ROLLING FATIGUE DAMAGE RESISTANCE

摘要

PROBLEM TO BE SOLVED: To combine welded joint characteristic, rolling fatigue damage resistance, and electric conductivity, all required of a rapid transit section, by specifying respective contents of C, Si, Mn, Cr, Mo, V, Nb, P and S in a rail steel to control electric resistance value and forming the structure of railhead into bainitic structure. ;SOLUTION: A rail steel is provided with a composition consisting of, by weight, 0.15-0.45% C, 0.10-0.50% Si, 0.50-1.80% Mn, 0.20-1.80% Cr, 0.01-0.60% Mo, 0.01-0.30% V, 0.01-0.05% Nb, ≤0.030% P, ≤0.030% S, and the balance Fe, and an electric resistance value represented by an expression is regulated to ≤26.5 μΩ.cm. Further, by regulating heat treatment conditions, the structure in the area within a depth of at least 15 mm, with railhead corner surface and railhead surface as the starting point, is formed into bainitic structure of ≥Hv 240 hardness. If necessary, 0.05-0.50%, by weight, Cu, 0.05-1.00% Ni, 0.005-0.050% Ti, and 0.0001-0.0040% B are incorporated into the above steel composition.;COPYRIGHT: (C)2000,JPO