PROCESS FOR PRODUCING PEARLITIC RAIL EXCELLENT IN WEARING RESISTANCE AND DUCTILITY

• Main Authors: SEKI, KAZUNORI, SATO, TAKUYA, YAMAMOTO, TAKESHI, UEDA, MASAHARU
• Format: Patent
• Language: English; French; German
• Published: 24.11.2010
• Subjects: ALLOYS; CHEMISTRY; FERROUS OR NON-FERROUS ALLOYS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUSMETALS OR ALLOYS; MAKING METAL MALLEABLE BY DECARBURISATION, TEMPERING OR OTHERTREATMENTS; MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVINGMATERIAL; METALLURGY; METALLURGY OF IRON; MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; PERFORMING OPERATIONS; PUNCHING METAL; ROLLING OF METAL; TRANSPORTING; TREATMENT OF ALLOYS OR NON-FERROUS METALS

The invention provides a method for producing a pearlitic rail by subjecting to at least rough hot rolling and finish hot rolling a billet comprising, in mass%, C: 0.65-1.20%, Si: 0.05-2.00%, Mn: 0.05-2.00%, and a remainder of iron an unavoidable impurities, wherein the finish hot rolling is conducted by rolling at a rail head surface temperature in a range of not higher than 900 °C to not lower than Ar 3 transformation point or Ar cm transformation point to produce a head cumulative reduction of area of not less than 20% and a reaction force ratio of not less than 1.25, and the finish hot rolled rail head surface is subjected to accelerated cooling or spontaneous cooling to at least 550 °C at a cooling rate of 2 to 30 °C/sec, thereby refining the rail head structure to attain a hardness within a predetermined range and improving rail wear resistance and ductility.