The possible reasons for the low ductility of low-carbon killed steel are as follows: high contamination of the steel with nonmetallic inclusions. The average total concentration proved to be higher in samples with unsatisfactory results from cold bending tests (0.151% as opposed to 0.103%); uneven distribution of nonmetallic inclusions. The variation in the number of nonmetallic inclusions in separate fields Qmax/QAv amounts to 3.5; high and uneven concentration of stringers (mainly sulfides). The linear inclusions in steel St. 3sp constitute 67.6% of the total number of inclusions. The high concentration of nonmetallic inclusions in samples with satisfactory ductility in cold bending tests indicates that cracks result from the simultaneous influence of several factors which impair the ductility.