PROCEDURE AND DEVICE FOR THERMAL TREATMENT OF RAILS Russian patent published in 2012 - IPC C21D9/04 C21D11/00 

FIELD: metallurgy.

SUBSTANCE: rails are cooled at cooling speeds in the range of 2÷20°C/sec with a smooth change in the speed of cooling during heat treatment, which allows to obtain a uniform finely dispersed structure of sorbite hardening to a depth of 22 mm from the surface and to obtain hardness on the roll surface to the HB401. Adjustment of cooling capacity of the gaseous medium is performed by a programed mode by means of a pulsed quasi-continuous and/or continuous injection of water into the air stream. Depending on the chemical composition of rail steel and the rail initial temperature being not lower than austenitisation temperature flow of the gaseous medium is controlled from 20 to 60 m³/min per one running metre of a rail, whereby the flow of injected water is up to 12 l/min per one running metre of rail. In addition, the water content in the gas medium is up to 0.2 litre of water per 1 cubic metre of air. The gaseous medium pressure is controlled in the range from 0.005 to 0.1 MPa.

EFFECT: versatility of the method and the device that allow for thermal treatment of rails of both carbon non-alloy steels and of alloy steel.

12 cl, 5 tbl, 4 dwg