Study On Bending Deformation And Residual Stress Of U75V Heavy Rail During Air Cooling Quenching

Rail on-line waste heat air cooling quenching technology is a new heat treatment process developed in recent years,which reduces the energy consumption of products,shortens the production cycle and improves the efficiency of heat treatment process.It is one of the most effective and economical methods to improve the comprehensive performance of rail at present.High-speed and heavy-load railway construction puts forward higher requirements on the comprehensive performance of rail.In order to ensure the running stability and riding comfort of high-speed train,the quenched heavy rail needs high section size tolerance and straightness.Rail is a steel with special-shaped cross section,which will produce complex bending deformation under the combined action of solid phase transformation and temperature change during cooling.If the bending deformation of heavy rail during air-cooled quenching is large,it needs a large straightening force and is easy to produce a large residual stress.Therefore,it is necessary to study the deformation of heavy rail during air-cooled quenching,and minimize the bending deformation caused by air-cooled quenching by air-cooled quenching of the whole heavy rail(the rail bottom is also air-cooled).In this paper,a fluid-solid-heat coupling finite element analysis model of U75 V heavy rail air-cooled quenching is established by using numerical simulation analysis method,adopting contraction jet,and considering both material nonlinearity and complex heat transfer boundary conditions.the temperature field,deformation and residual stress are simulated and calculated by ANSYS software,and then the temperature variation law(especially during solid phase transition),bending deformation law and residual stress distribution law of heavy rail during cooling process are analyzed.At last,the influence of air-cooled quenching jet setting parameters(jet air spacing,height and pressure)on the temperature field,bending deformation and residual stress of heavy rail was studied,and the jet setting parameters were optimized with the bending degree of cooled heavy rail as an index,and a set of better jet setting parameters(spacing 120 mm,height 30 mm and pressure30kpa)were obtained.The research provides important reference value for the application of on-line waste heat air cooling quenching technology and the design of air spraying device,and has important practical significance for improving the quenching quality of heavy rail.