| 摘要 |
PURPOSE:To improve the resistance to fracture of the upper filler of a rail in producing a hard top rail by transforming the entire top of the rail to martensite then heating the same to tempered martensite thereby decreasing the residual tensile stress in the upper filler of the rail or converting said stress to residual compressive stress. CONSTITUTION:The entire top part of a rail consisting of a rail head 2, a head side face 3 and an upper filler 1 is heated to the temp. higher than the A1 transformation point by a heater 7 of a hardening device 6. When the rail R attains the temp. before it falls from the Av1 transformation point, water or the like is ejected from a cooling apparatus 8 to the faces 2, 3 and the upper filler 1 to cool approximately uniformly the same until the martensite transformation ends. The entire head of the hardened rail is heated to 400 deg.C-A1 transformation point by a heater 10 of the succeeding tempering device 9 to charge the martensite structure to tempered martensite structure. The upper filler 1 and the faces 2, 3 are uniformly and quickly cooled by the cooling similar to the above in a cool apparatus 11 right after said heating. The residual tensile stress in the upper filler is then decreased or converted to residual compressive stress. |
