EXPERIMENTAL INVESTIGATION OF THE MECHANICAL-PROPERTIES OF QUENCHED RAILS FOR DIFFERENT QUENCHING CONDITIONS USING THE TEMPERATURE DIRECTLYFROM ROLLING HEATING

Because of increasing rail traffic in conjunction with the application of greater axle loads, there is a need to provide higher strength ste el mil. Quenching treatment along the whole steel rail, directly using the temperature from the rolling heating, has been employed in the ro lling line. Sis different quenching conditions were used, from 720 to 840 degrees C, in order to seek the optimum heat-treatment schedules o f the steel rails. The microstructure and mechanical properties of the quenched steel rails were investigated. The test results show that th e conventional mechanical behaviour of the quenched rails surpasses th e West Europe Standard: sigma(0.2)>740MPa, sigma(b)>1160MPa, delta(5)> 9%, The hardness distribution over the cross-section of the quenched r ails is uniform, the hardness difference along the longitudinal sectio n of the quenched rails being Delta H-b<30. When the quenching tempera ture is 740 degrees C, a quenched steel rail with the best mechanical properties and with smalt pearlite nodules can be obtained.