The precipitated phases in microalloy steel 40MnV-0.36~0.40C

1.36~1.40Mn

0.55～0.65Si

0.8 ~0.9V

0.011～0.016Ti

0.021～0.045Al

0.007～0.016N have been calculated by Thermocale and Dicta software

and the chemical compositions

morphology and distribution of the precipitated phases were studied by electrolytic analysis X- ray diffraction analysis and transmission electron microscope examination. The results showed that minor N and Ti in steel led to coarse particle of TiN with size 50 nm precipitated at liquid- solid two phase region. With temperature decreasing

the size of precipitated phases gradually decreased to less than 10 nm of which the shape was modified to round from square

and the V and C content in precipitated phases increased besides the N and Ti content decreased. With aluminum content in steel increasing

the amount of VN precipitation decreased.