Effect of Deformation Parameters on the Quality of Billets and Grinding Balls Made of Rail Steel Rejects

• Published in: Steel in translation 2022-08, Vol.52 (8), p.753-759
• Main Authors: Umanskii, A. A., Yur’ev, A. B., Simachev, A. S., Dumova, L. V.
• Format: Article
• Language: English
• Subjects: Billets; Chemistry and Materials Science; Continuous casting; Cross-sections; Defects; Deformation effects; Ductility; Impact resistance; Ingot casting; Inhomogeneity; Materials Science; Metallurgy; Parameters; Rail steels; Rolling mills; Stretching; Surface hardness; Swaging; Temperature effects
• ISSN: 0967-0912; 1935-0988
• DOI: 10.3103/S0967091222080150

The effect of rolling parameters for billets and grinding balls during production from the rejects of K76F rail steel exerted on defect formation probability upon deformation has been studied. The simulation of the rolling process for high-grade billets based on the rejects of continuously cast K76F rail steel ingots using a DEFORM-2D software package has provided a significant effect of partial stretching (swaging) coefficients throughout passes, an increased feed turning frequency and rolling temperature exerted on the defect formation probability characterized by a maximum value of the Cockcroft–Latham criterion throughout the feed cross-section. It has been shown that the increase in stretching (swaging) coefficients throughout passes, due to an intensified rolling mode and to an increased turning frequency makes it possible to reduce the probability of defect formation during rolling at the expense of reduced temperature inhomogeneity throughout the feed cross-section. The revealed effect of temperature increase on the reduction of defect formation probability is caused by an increase in the rail steel ductility. Based on the obtained data, general recommendations have been formulated concerning the directions of improving rolling modes for billets made of trail steel rejects, as well as the restrictions of the application of these recommendations in practice. Based on rolling simulation for grinding balls made of rail steel rejects using a helical rolling mill, a significant effect of increased deformation temperature on a decrease in ball crack formation in the axial zone caused by increasing steel ductility has been established. Thus, a novel rolling mode for grinding balls made of the rejects of K76F grade rail steel that provides an increase in impact resistance of grinding balls while maintaining a high level of surface hardness has been developed. The efficiency of this mode has been confirmed by the results of pilot testing with the use of a ball rolling mill at JSC Gur’ev Metallurgical Plant.