Influence of Cooling Speed on Microstructure of Nb-V Microalloyed High Strength Steel

The experiments of a microalloyed high strength steel under heating, heat preservation and cooling at different speeds were conducted on the thermal-simulator of THERMECMASTOR-Z.And the microstructure was observed by Zeiss Axioplan2 universal metallographic optical microscope.The effects of cooling speed on microstructure and phase transformation of the microalloyed high strength steel were analyzed.It has been found that the temperature points and temperature range of phase transformation decrease with the increase of the cooling speed.The ferrite grain will be refined and the ferrite amount will decrease with the increase of cooling speed.At the same time, deformation can promote phase transformation.