POST-WELD HEAT TREATMENT METHOD FOR WELDED JOINTS OF BAINITIC RAILS

摘要

#$%^&*AU2018214003A120190221.pdf#####ABSTRACT The invention relates to the field of manufacturing technology of railway rails, and provides a post-weld heat treatment method for welded 5 joints of bainitic rails, which can control the longitudinal hardness of the tread of welded joints of bainitic rails within a reasonable range. The post-weld heat treatment method in the invention comprises the following steps sequentially performed: A. performing a first cooling for the welded joints with a temperature of 1500-1600 C to 150-250 C, wherein 10 the first cooling is naturally realized by air cooling; B. heating the welded joints to 880-960 C by an intermediate-frequency induction profiling electric heating coil and/or an oxygen-acetylene flame profiling heater; C. performing a second cooling for the welded joints, stopping the second cooling when the welded joints are cooled to 180-250 'C , and 15 immediately performing a third cooling to the room temperature of 5-40'C; wherein the second cooling is rapidly realized by applying a cooling medium, the initial cooling temperature of the second cooling is above 800 C, and the third cooling is naturally realized by air cooling.-- Longitudinal hardness curve of the rail ,o- head tread of welded joints -Measurement line of softened zone of welded joints -110 -100 -90 -80 -70 -50 -50 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 110 Distance from the center of the welding seam/nmm Fig. 1 -4-Longitudinal hardness curve of the rail head tread of welded joints -- Measurement line of softened zone ofwelded joints 10 -110 -100 -90 -80 -70 -60 -50 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 110 Distance from the center of the welding seam/mm Fig. 2