The longitudinal crack with 0.3 mm depth occurred in φ11.5 mm cold drawn products of low carbon high sulphur free cutting structural steel (0.07C

0.86Mn

0.06P

0.32S) to product some batches of rejection. The analysis results by sampling indicated that the rating unit of banded structure in φ14 mm cold drawing blank was up to 4 and the section reduction in cold drawn one pass was up to 32.52% which led to crack formed in cold drawing. With overheat control of molten steel during casting

finishing rolling temperature increasing to 1050 ℃ from 850 ℃ during continuous rolling of cold drawn blank

spraying cooling and 650 ℃ self tempering

the rating unit of banded structure of φ14 mm cold drawing blank decreased to less than 1.5

moreover the section reduction in cold drawn pass decreased to less than 30.5%

thereby the longitudinal crack in Φ11.5 mm Cold drawn products was avoided.