HIGH-INTERNAL-HARDNESS TYPE PEARLITE STEEL RAIL SUPERIOR IN FLASH-BUTT-WELDED JOINT CHARACTERISTICS, AND METHOD FOR WELDING THE SAME

摘要

PPROBLEM TO BE SOLVED: To provide a high-internal-hardness type pearlite steel rail which has increased hardness in a depth range of 25 mm from the surface layer of a railhead and is superior in flash-butt-welded joint characteristics, and to provide a flash butt welding method for obtaining a weld joint having superior characteristics. PSOLUTION: The pearlite steel rail has a composition composed of, by mass%, 0.73-0.85% C, 0.5-0.75% Si, 0.3-1.0% Mn, 0.035% or less P, 0.0005-0.012% S, 0.2-1.3% Cr and the balance Fe with unavoidable impurities while controlling a value of [% Mn]/[% Cr] to 0.3 or more but less than 0.9, and has an internal hardness of Hv 390 or more but less than Hv 480 in the head part at least 25 mm deep from the surface layer of the railhead in a base metal of the rail. The welding method includes flash-butt-welding the pearlite steel rail in an upset amount range of 20 mm or more, starting the cooling of the railhead within 70 seconds after the welding, and finishing the cooling of the railhead in 25-60 seconds after having started the cooling. PCOPYRIGHT: (C)2010,JPO&INPIT