Resrarch On Electromagnetic Heating Strengthening Of U71Mn Rail Swelled Joint

There is a lack of systematic theoretical and experimental research on crackingprevention and reinforcing of U71Mn rail swelled joint at home and abroad. The work isbased on the thoughts, and the electromagnetic heat is applied to embedding crack inU71Mn rail swelled joint and reinforcing of the welded toe in theoretical analysis,numerical simulation and experimental surveys.The current density is deduced by fluid mechanics in the welded toe with semicirclesuperficial crack. Stress intensity factor expression is also obtained after discharge. Anexample gives current density and the stress intensity factor relation curves. Using theANSYS to simulate stress intensity factor U71Mn rail swelled toe with semicirclesuperficial crack before and after discharge.The temperature field expression of crack tip for U71Mn rail steel welded joint withembedding crack after discharge is showed;the temperature field expression and residualstress field distribution of crack tip for U71Mn rail welded joint with embedding ellipticalcrack is given at the time of pulse current discharge by software ANSYS;when a test loadwas applied to welded joint with embedding crack,stress field distribution of crack tip isanalyzed.The temperature field of for U71Mn rail welded toe is given at the time of pulsecurrent discharge by software ANSYS; When a tension was applied to welded joint, stresschange of welded toe is analyzed before and after discharge. The defect location of weldedtoe is detected by the TZ-2H ultrasonic flaw detector. The contrast of sound-ranging ofwelded toe is given before and after pulse discharge using the relation between speed ofsound and residual stress. Thereby the change of residual stress in welded toe is checked.The sample of U71Mn rail material with one-sided crack is discharged byelectromagnetic heating effect. A white bright layer formed around the crack tip isobserved; a mechanical properties test on welded joints existing in Arc manually and TIGis made，which are the samples of U71Mn rail materials. The paper provides the reference for further study of reinforcing of rail swelled jointNumerical simulation results, the theoretical analysis and experimental phenomena cantest that the technology of electromagnetic heat crack arrest is applied to rail the weldingfield.