The causes of surface cracks formation of H beam of Nb-V microalloying steel BS55C-0. 14~0. 17C
0.45~0.55Si
1.25~1.45Mn
0.08~0. 10V
0.03~0.05Nb have been analyzed. The results showed that the steel was sensitive to longitudinal crack at solidification and its plasticity at 700~950 ℃ was lower
therefore
the cracks were easily produced at surface of H beam. Based on analysis of 168 heats production data of Nb-V microalloying steel BS55C
it was obtained that it was available to effectively decrease the surface cracks of H beam of Nb-V microalloying steel by using LF refining
controlling [s]≤0.015% and [P]≤0.020%
optimizing cast nozzle
adopting weak secondary water cooling and avoiding straightening at 700~900 ℃