Influence by Intermediate Crack of Continuously-cast Round as Tube Stock on Quality of Tubes

The results of experimental operations of pipe-piercing and rolling with CC rounds show that using CC rounds bearing intermediate cracks as tube stocks may cause defective internal stripped folds and scaled folds of the final products. With any of such CC rounds, the so called “defective cavity” is to be formed in the pierced shell just in front of the well-set plug, and thus lead to the occurrence of the said internal fold defects of the pipe, which is a characteristic that differs from the pipe-rolling with the forged or round billet.