The study of high-strength steel capacity for plastic deformation in bending angle of 90°

The production of ships, automobiles, machinery is a cause of manufacture of quantity different parts of complex shapes produced by sheet metal bending. However, not all steels subjected to plastic bending. Bending process of high-strength steels requires the use of major radius punch in comparison with punch for bending carbon steels, as it is possible the appearance of cracks. The aim of this work is to defi ne a minimum R/h ratio for high-strength steels with a 400 HBW hardness during processing of free bending method at the 90º angle. For this purpose the study of ability of high-strength sheet steel 400 HBW hardness to plastic deformation during the bending at the angle of 90º was made with a help of mathematical modeling in the software package Deform-3D. Initially the tensile tests in accordance with GOST 1497-84 was made to obtain data on the plastic properties of high-strength steel. The normalized criterion Kokraft-Latham was adopted as a criterion of destruction. The new material has been set in the software package Deform-3D according to the experimental data. Than on the basis of obtained plot the modeling of the stretching process with a fi nite element method was made to determine the fracture criterion (K) for the high-strength steel. The calculation results obtained with a use of created kinematic model are confi rmed by actual bending testing of the high-strength steel.