Computational and experimental modeling of new forging ingots with a directional solidification: the relative heights of 1.1

Abstract

The work's purpose is to increase the forging ingot's quality. A crystallization mechanism of shortened ingots has been investigated. The shortened ingots allow changing a direction of the metal solidification. The rational geometry of the ingot (a ratio of height to diameter and a value of taper) needs to be determined. The special technique of the theoretical and experimental investigations has been developed. The theoretical investigations have been carried out by finite element method. An adequacy test of the theoretical results has been carried out by experimental investigations on transparent and metallic models (pure aluminum) of the ingots. The macrostructure investigations of the shortened ingots with directional solidification have been produced. A hardness distribution on the longitudinal section has been investigated. It was found that for the ingot with the ratio of H/D = 1.1 the most part of the ingot's body (60-70%) has a dense, homogeneous and small-grained structure. The small grain, which provides a dense structure, forms at the bottom and in the corners from the bottom side. The distribution of the grain dimensions along the ingot radius at different height levels allows to conclude that the bottom and middle parts along the height have the same small-grained structure. The high and uniform hardness values are characteristic for the ingot with H/D = 1.1. The middle and hot-top layers of the ingot have commensurate hardness, which have a difference from the bottom part maximum on the 5%. The ingot with the reverse taper of 7% allows to make a most dense and homogeneous structure. Thus, the improvement in the large forged quality ingots is possible by providing the directional solidification and reverse taper.

Procedure for calculating the thermoacoustic pressure fluctuations at boiling subcooled liquid

“…Similar problems arise in metallurgical production when casting large-capacity ingots [7,8]. In these processes, there were water pressure fluctuations in the cooling channels of pallet hollows when molten steel crystallized (a temperature of ~1,550 °С) that were not considered in studies [7,8]. In the channel with a boiling heat carrier there are acoustic effects, manifested in the form of "white" noise or steady harmonic oscillations of pressure.…”

“…They note that subcooling boiling has a wide scope of industrial applications, including nuclear reactors. Similar problems arise in metallurgical production when casting large-capacity ingots [7,8]. In these processes, there were water pressure fluctuations in the cooling channels of pallet hollows when molten steel crystallized (a temperature of ~1,550 °С) that were not considered in studies [7,8].…”

Modeling and improvement of saddling a stepped hollow workpiece with a profiled tool

“…One such operation is saddling. It is possible to eliminate the saddling operation by using new ingots [3,4]. As stated in paper [5], in order to improve the quality of forgings for responsible purposes, to develop new and promising power plants with enhanced capacity, a technology was devised for the production of large-sized rings.…”

“…Work [6] assesses the technical advantages of producing large-sized forgings for responsible purposes. However, the cited studies [2][3][4][5][6] do not describe the technological modes and recommendations for rings forging.…”

Development of theoretical foundations for the hot metal desulfurization with magnesium reduced by the heat from exothermal transformations

“…Analysis of data from the scientific literature has revealed known current studies into the use of a finite element analysis for the simulation of physical-chemical processes in the melt of steel and hot metal [15,16]; those papers, however, mostly explored the processes of crystallization and the formation of chemical heterogeneity in the final melts. This relates to the fact that existing commercially-available finite-element programs are not yet fully able to simulate the course of purely chemical processes.…”