Effects of finishing and coiling temperatures on microstructure and precipitate of Ti-V micro-alloyed steel
The Ti-V micro-alloyed steel was subjected to 6-pass compression deformation tests using a Gleeble-3800 thermomechanical simulator.Under the given conditions of an initial rolling temperature of 1 050 ℃,a strain rate of 1s-1,and an inter-pass time of 10 s,the effects of finishing and coiling temperatures on the evolution of microstructures and the precipitation phase in Ti-V micro-alloyed steel have been studied.The result shows that when the finishing temperature reduces from 850 ℃ to 775 ℃,the grain size of ferrite decreases from 15.1 pam to 3.8 μm.It is found that reducing the final rolling temperature has the effect of refining the ferrite grain size.The Ti-V micro-alloyed steel has precipitation phenomena under different conditions.When the finishing temperature is 800 ℃ and the coiling temperature is 550 ℃,the precipitation phase has both coarse and small,with an average particle size of 34.6 nm.The precipitation phase mainly exists in the form of dispersed distribution and also in the form of chain distribution.Most of them are spherical or elliptical,and a small part is cubic,rectangular,or irregular.From the perspective of thermodynamics,the morphology of the precipitation phase depends mainly on the interfacial energy,when the interfacial energy plays a significant role,the morphology is spherical,when the precipitation phase grows up sufficiently,and the interfacial energy does not play a dominant role,the morphology changes to cubic or rectangular.In addition,the Ti-V micro-alloyed steel under different deformation conditions has relatively high dislocation density,This is because the pinning effect of the precipitation phase on dislocations can activate new dislocation sources in other slip systems,resulting in multiple slip phenomena,thereby increasing dislocation density,and resulting in dislocation strengthening.
Ti-V micro-alloyed steelmicrostructuresprecipitation phasecontrolled rolling
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