The Research Of Organizational Control On Bainite Rail Steel

Railway is an important product of the capitalist revolution, it appears to play a veryimportant role in the development of society. Compared with other rail Bainite rail has thesuperior ductility and toughness, higher fatigue resistance and wear resistance. Because ofits good strength and toughness,Bainite rail quickly developed into a new generation ofsteel.but it will still appear cracks and other issues when used.Therefore,we simultaneouslyuse the advantage of bainitic rail steel,we also need to control its organizational with CCTcurve,finishing rolling temperature and cooling rate. Through such three aspects,thebehavior of the recrystallization behavior,the phase transition and the cooling controlduring hot rolling process,studing the effect on the Bainite rail steel organization withdifferent heat hardening after rolling.This paper uses the Bainite rail steel as the research object to analysis in these twomain aspects. First,observed and analyzed its organization after heat treatment by ZEISSoptical microscope and Zeiss SUPRA55scanning electron microscope.Sceond, studiedBainite rail recrystallization behavior under different conditions of thermal deformation byusing the Gleeble-1500D thermal simulation machine,and analyzed the influence of thedeformation process parameters on recrystallization behavior through multi-passcompression test.Studies have shown that: the heat treatment process with different cooling methodshave a great impact on the organization of test steel. Bainite rail cools in oil, itsorganization is lath Martensite and Austenite.When cooling slowly,the organization isFerrite and granular Bainite. In the salt bath furnace350℃isothermal quenching15min,30min,60min the organization is lamellar bainitic.we get Bainite plus residual Austenitewhen tempering. In a single pass thermal simulation experiment, Bainite rail dynamicrecrystallization occurs at1100℃degree centigrade. At900℃-1050℃degree centigrade,it just occur a small amount of dynamic recovery, the dynamic recrystallization does not occur. When the iterval time is20s, we can discriminate the900℃degree centigrade asnon-recrystallization region,950℃degree centigrade partial recrystallization,1000℃-1050℃degree centigrade as complete recrystallization. Multi-pass compression,the program one and two rolled in the first pass reduction at1100℃degree centigrade,recrystallization occurred. The second and third pass reduction are the process ofaccumulation of strain. The forth rolled18percent at910℃degree centigrade, Thereappeared recrystallization tendency.Dynamic recrystallization due to large reduction. Theprogram three rolled at complete recrystallization region in the first and second passreduction, the other two pass reduction rolled at non-recrystallization region, avoidingpartial recrystallization region can make the grain more refined.Research found that:Bainite steel exists metallurgical defects,such as banded structure and MnS inclusions.Prone to Martensite during the cooling process, which is the cause of cracking of the rail.