Dissimilar Welding Of Bainitic Steel Crossing And U71MN Rail

In this paper a method for welding air-cooling bainite steel crossing and U71Mn steel rail was pressed,through advanced Gleeble thermal simulation to determine the welding technology air-cooling bainte steel crossing and U71Mn rail steel were successfully weld together baseing on the method of welding high manganese steel crossing and U71Mn rail steel and using.Firstly Gleeble thermal simulation test technology was adopted determine the distribution of temperature field and parametes of top edge welding process for the resisting welding of banite steel crossing and U71Mn steel rail.At the 4mm location away from the welding line,the highest temperature was 1238℃; At the 14mm location away from the welding line,the highest temperature was 1058℃; At the 24mm location away from the welding line,the highest temperature was 704℃; At the 28mm location away from the welding line,the highest temperature was 462℃;.The prime pressure is 30Mpa for the top edge welding of air-cooling bainite steel crossing and U71Mn steel rail.Based on these simulation results,a flash experiment was contrived out for air-cooling bainite steel crossing and U71Mnsteel rail small workpieces on a small flash welding machine.The best technologies and process determined way were welded with U71Mn rail steel directly,and the joint was normalized at 920℃for 10 min,on these bases the rail air-cooling bainite and U71Mn steel rail were welded out flash welding experiment.The optimum technology of the flash welding of air-cooling bainite steel crossing and U71Mn steel rail was that flashing allowance was 17.5~18.0mm,upsetting length was 13.0～17.5mm,and preheating times was 9.The results of conventional mechanical properties and static bending, fatigue and drop hammer experiments for entire rail welded joints showed that,welded joint for air-cool banite steel crossing and U71Mn steel rail had high toughness and strength,which reached to some standards and the actual use require mentsThere was no carbide in HAZ of air-cooling bainite steel,there was no martensite in HAZ of U71Mn steel and there was much austenite retained in fusion zone of air-cooling bainite steel analysed by metallograph,x-ray diffraction SEM and TEM.