STUDY OF THE MUTUAL INFLUENCE OF FACTORS ON THE PLASTICITY OF STEELS AND ALLOYS DURING HOT DEFORMATION

Abstract

This article presents the results obtained in analyzing the influence of thermomechanical parameters on the ductility of metals and alloys during hot deformation. It is known that ductility is influenced by factors such as deformation temperature, strain rate, and stress state index. However, numerous experimental studies show that for some, primarily difficult-to-deform steels and alloys, the mutual influence of the aforementioned parameters is no less significant. Accordingly, a method for approximating the results of studying the plastic of metals and alloys in a hot state is proposed. This method takes into account this combined influence and allows for obtaining more reliable information on the plastic properties. This is confirmed by the results of a study of the ductility of complex-alloyed chromium-containing steel grades and difficult-to-deform nickel and chromium-nickel alloys, known in the scientific and technical literature as superalloys. The ductility studies were conducted using three types of tests: upsetting, stretching, and torsion at various temperatures and strain rates for various difficult-to-deform steels and alloys, which made it possible to obtain the most complete and reliable data. A new experimental data approximation method allows for more accurate determination of the critical degree of deformation under various temperature and deformation parameters. This, in turn, will improve the accuracy of calculated process parameters used in the manufacture of hot-formed products while minimizing the likelihood of various surface imperfections caused by the exhaustion of the plasticity of the material being processed. The new method has already been applied and successfully tested in the development of new and improved technologies for the manufacture of hot-pressed pipes, specifically in terms of developing efficient pressing modes.