The chemical composition

scanning electron microscopy and auger electron spectroscopy were used to analyze the reasons of the strip fracture of high strength IF steel HC250IF containing phosphorus during straightening in pickling

&

rolling process. It is confinned that the content of B is too low and the segregation of P at grain boundary could not be inhibited

and the FeTiP or Fe3P compound formed at the grain boundary resulting in brittleness is the basic cause of strip fracture. By optimized process for adding boron

increasing the content of B from 0.0002% 〜0.0007% to 0.0008% ~ 0.0012%

controlling strictly the content N≤ 30 x 10

-6

and vacuum cycle for 8 min after adding the boron iron in RH process

it is to ensure the uniformity of the composition

the strip fracture of high strength IF steel containing phosphorus during straightening in pickling

&

rolling

process can be effectively avoided.