Method for online laser broadband quenching on surface of steel rail

Abstract

The invention discloses a method for online laser broadband quenching on a surface of a steel rail, which can synchronously improve the hardness and the toughness of the steel rail, and can realize online laser quench hardening. The method comprises the following steps: an induction spray gun and a laser emitting head of an optical fiber laser are fixed on a mechanical arm; firstly, the induction spray gun is used for spraying one layer of light absorbing paint (graphite particles+SiO2 particles with the mass percentage of 5-20%, particle size of the particles within 50 nm-1 um) on the surface of the steel rail; and then, the wheel-rail contact surface of the steel rail is quickly scanned by using the optical fiber laser to obtain a laser quench hardened layer with the structure as the martensite, bainite and retained austenite mixed structure. The method uses the afterheat of the online steel rail to reduce the space, the energy and the resource; the optical fiber laser is smaller than a CO2 laser in volume, so that the movement is convenient; and quenching bands are adopted for laser quenching, and have certain distances, so that the crack phenomenon is reduced.

Description

technical field [0001] The invention relates to a laser surface strengthening method, in particular to a method for on-line laser broadband quenching of the rail surface. Background technique [0002] Steel rails are one of the main components that enable high-speed trains and freight trains to operate. The wheels of the train are in direct contact with the rails, and the train moves forward through the friction between the wheels and rails. The quality of the rails directly affects the safety and stability of the train during operation. At present, the steel rails are mainly U75V and U71Mn steel rails. However, with the increase of the axle load, speed and carrying capacity of the train, the damage of the two main rails has become more and more serious, and deficiencies have been exposed, such as: the deficiencies in wear resistance and fatigue resistance, etc. Rail damage has always been a key problem to be solved urgently. The damage types mainly include corrugation, si...

AI Technical Summary

Problems solved by technology

[0007] Based on the laser quenching and heat treatment technologies disclosed above, there are still key problems to be solved: (1) Laser quenching is performed on the entire surface of the rail, and there is a phenomenon of "thermal expansion and contraction" in the hardened layer, and the concentration of residual stress is easy to cause The hardened layer cracks; (2) the use of pulsed semiconductor lasers solves the problem of laser absorption, but the equipment has low efficiency and is not suitable for long-term continuous processing; (3) the use of huge CO 2 The laser is not easy to move and has a complex structure, so it is not suitable for online laser quenching equipment

(5) The process steps of some patents are complicated and diverse, and difficult to control and operate

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