| 摘要 |
PURPOSE:To obtain a rail having excellent resistance to fracture of the upper filler thereof in producing a hard top and hardened end rail by austenitizing the entire top of the rail then cooling the same to form fine pearlite thereby providing residual compressive stress to the upper filler of the rail. CONSTITUTION:The entire top of a rail consisting of a rail summit 2, a top side face 3 and an upper filler 1 is heated to the temp. higher than the A1 transformation point by a hardening device 6. Such rail R is allowed to cool and when it attains the temp. before it falls from the Ar1 transformation point, air or the like is ejected from a slow cooler 7 to the faces 2, 3 and the upper filler 1 to cool approximately uniformly the same until pearlite transformation ends. Water or the like is ejected to cool quickly the faces 2, 3 and the upper filler 1 by a quick cooler 8 right after the end of the transformation. Then the upper filler 1 exhibits the same fine pearlite texture as the texture of the faces 2, 3, thus having higher strength and residual compressive stress. The fatigue limit is thus extremely improved and the resistance to fracture is considerably improved. |
