EFFECTS OF SLIGHT CC BILLET CRACKS ON STEEL PIPE QUALITY

The developing of slight CC billet cracks during two-roll cross piercing and two-roll cold-rolling are investigated. Experiments shows that the slight cracks can not be welded but enlarges, that the longitudinal and central cracks of a CC billet lead to internal and external steel pipe wreckages, and that the transverse cracks during cold-forming develop into "herringbone" cracks.