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U71Mn,U75V and REⅡare employed in this text, smelt the ingots with rare earth elements, make use of Cleeble-1500D thermal simulation machine to do high temperature thermoplastic tensile tests and recrystallization compress tests.Ingots smelted is adding the rare earth elements to U75V ingot, observe the inclusion morphology of heavy rail steel.The result shows that, suitable content of rare earth elements addition could change appearance of the inclusion, decrease the diameter of the grain and dispersed, thin the slice space of the pearlite.In high temperature thermoplastic tests, study the plastic viriation in every temperature ranges, and study the effect of micro-alloy elements V, Nb and RE on the high-temperature thermoplastic of heavy rail steel, coMPare analyzing the fracted appreance of tensile specimen. The result shows that, in brittle zoneⅠ(1200℃～1300℃), the plasticity of every steels are very low, nearly 0; in brittle zoneⅡ(850℃～1200℃),the plasticity is very well, in brittle zoneⅢ(low than 850℃),the plasticity decrease. V has important influence on the plasticity of heavy rail steel in brittle zoneⅢ. Section shrinkage curve shows that, the section shrinkages of U75V are lower than the ones of REⅡ,that means suitable content of rare earth elements can decrease the grain size to improve the capability.U71Mn,U75V and REⅡare employed in single-pass compression test by Cleeble-1500D thermal simulation machine. By coMParing the true stress-true strain curve and RTT curve at different deformation to study the effect of deformation and micro-alloy elements on dynamic recrystallization of U71Mn,U75V and REⅡ. The result shows that,the higher the deforming temperature and lower deforming speed,the easier the dynamic recrystalization occurred, because of the effects of micro-alloy elements V and RE, the beginning time of dynamic recrystallization of U75V and REⅡis delayed, so that dynamic recrystallization activation energy of deformed austenite is increase, so it can restrain austenitic dynamic recrystallization. According true stress-true strain curves, we can calculate dynamic recrysatllization activiate energy Q and temperature compensated strain rate factor Z of U71Mn、U75V and REⅡ, which can provide accordings to control the structure and capability.Determine the true stress-true strain curves of the two kinds steels at different deforming condition and internerate rates of them at different dearance time when isothermal deformation by single-pass and double-pass compression simulation test with U75V and REⅡ,study the effect of the deformation condition on static recrystalllization, analyze the variety of static recrystallization. According to single-pass and double-pass compression deforming data to adjust and draw up the multi-pass compression technics, restrain static recrystallization occuring, control the dynamic recrystallization occuring, refine austenitic grain size to improve the mechanical properties effectively.
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