Patent ID: 8388775

Claim:
A process for in-line thermal treatment of a rail, having a head, immediately at an exit of a rolling system wherein the rail has reached a rolling residual temperature in a range of about 900° C. to 950° C., the process including the following steps: a first cooling step in air of the rail until reaching a surface temperature of the rail head of at least 720° C.; a second step of cooling the rail head by a cooling fluid until reaching a surface temperature of the rail head from 50 to 150° C. above the Ar3 temperature in order to avoid a phase transformation from austenite to pearlite; a third step of cooling the rail head in air whereby the heat of the inner layers tempers the superficial layers up to a temperature of 720-840° C. and the surface temperature is equalized up to the temperature of a superficial layer of the rail head, said superficial layer having a depth in the range between 15 and 25 mm from the surface; a fourth step of cooling the rail head by a cooling fluid until reaching a surface temperature of the rail head lower than 500° C. whereby the phase transformation from austenite to pearlite occurs; wherein said pearlite has an uniform structure with fine granulometry in said superficial layer whereby uniform mechanical properties are obtained along said superficial layer.