THE DISTRIBUTION OF DEFORMATION IN TUBE ROUNDS DURING MANNESMANN PIERCING

The distribution of deformation in the section of tube rounds during Man-nesmann piercing has been experimentally studied with a view to establishing itsmechanism. It was shown: 1. The distribution of the intensity of strain across the diameter of a tuberound is inhomogeneous with W-shaped. The intensity of strain on the sur-face layer and centre layer is stronger than that on the intermediate layer. 2. Its inhomogeneity increases during the process. 3. Distinct deformation at the centre of the tube rounds has taken place be-fore the cavity occurs, so that the fracture is tough. 4. It is proved that the results obtained by adopting three experimental meth-ods are very alike.