METHOD OF HEAT TREATMENT OF RAIL WELDED JOINTS Russian patent published in 2007 - IPC C21D9/04 

FIELD: heat treatment of welded joints of long-cut rails and jointless lengths.

SUBSTANCE: to enhance strength and hardness of rail head at area of welded joint and reduce its liability to brittle fractures at complex shape of fracture, rail is heated over entire section in area of welded joint to temperature of beginning of phase transition in metal at shape of temperature field distribution close to trapezoidal where upper base of trapezium is rail head heating zone whose width is equal to zone of welding thermal effect and lower base of trapezium is rail foot heating zone whose width exceeds upper base by at least 2-3 times, thus ensuring self-tempering of rail head after its cooling. Rail head is held at heat between completion of heating process and beginning of hardening which is necessary for equalization of temperature in section and forming of homogeneous structure in entire heated volume. Then, rail head is cooled down positively by means of compressed air to temperature of completion of structure transition.

EFFECT: enhanced strength and hardness of rail head; reduced power requirements of process.

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