The microstructure and dynamic CCT curves of low carbon steels with different boron contents at different cooling rate were obtained through multi-pass hot compression deformation on Gleeble-3800 thermal mechanical simulator.The effect of boron on the microstructure and the dynamic CCT curves of the test steels was analyzed.The results show that the steel with boron content 0.0009％ has more stable transformation process than that without boron addition,and the formation of ferrite,pearlite and bainite can be restrained effectively by adding boron alloying element,which leads to the dynamic CCT curves shifted to the right; because of boron addition,bainite can be obtained under slower cooling rate (0.2°C/s) and the critical cooling rate to gain martensite is decreased,which improves the hardenability of the steel.
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