Forecasting Increase of Quality of Large-Sized Forgings Used for Stamping, Piercing, and Rolling of High-Duty Products

Abstract

When utilizing current combined systems of manufacturing large-sized shaft forgings, there is a tendency towards using an integrated approach, which consists in optimizing the shape of forged ingots and methods of their forging, intensifying shear strains in the axial zone of the ingots during their plastic deformation, and eliminating asymmetry of external forces at various points along the cross section of the ingot being deformed. This paper presents the results of the comparative analysis of quality of shaft forgings when forging ingots with a three-beam symmetric and asymmetric cross-section, as well as with the traditional octahedral cross-section, are used for the manufacture of shaft forgings. It has been shown that the use of forging ingots with a three-beam symmetrical and asymmetrical cross section provided an increase of KCU by an average of 4.3% and 13.1%, and of density by 17.5% and 21.0%, respectively, in the absence and presence of inert gas (argon) blowdown of the melt in the casting ladle before casting it into ingot molds. Their use also contributes to an increase in the number of forgings, suitable for ultrasonic testing, according to the C/c class with a permissible equivalent discontinuity diameter of ≤ 3 mm.