INFLUENCE OF ELECTROSLAG HEATING AND METAL STIRRING ON THE PHYSICAL HOMOGENEITY OF EXPERIMENTAL 40CR STEEL INGOTS

Abstract

A methodology was developed, and experiments were conducted to obtain experimental steel ingots of grade 40Cr under laboratory conditions using a combined external influence in the form of heating and metal stirring during solidification. Ingots weighing 120 kg were cast in sand-clay molds in two variants: without external influences (control ingots) and with heating and metal stirring (experimental ingots). Electro-slag heating was used to supply heat to the metal surface in the feeder head, while metal stirring was performed by blowing argon into the liquid core of the ingot using a submerged lance. Stirring began 7–8 minutes after the start of ingot formation and ended 30–35 minutes later. The interval between blowing cycles, of which there were five, ranged from 5 to 6 minutes, with each blowing lasting approximately 30 seconds. To investigate the quality of the obtained ingots, vertical axial templates 20–25 mm thick were cut from them. The surface of the templates closest to the ingot axis was ground, followed by the obtaining of sulfur prints using the Bauman method and etching to reveal the macrostructure. Samples were taken from the templates to determine the hardness, density, and mechanical properties of the metal.According to the conducted studies, the macrostructure of the experimental ingots, unlike that of the control ingots obtained without external influence, showed no shrinkage defects, including axial porosity. Measurements of hardness and density, as well as mechanical testing, indicate the absence of any noticeable reduction in metal properties in the upper axial region of the experimental ingots. In contrast, a sharp decline in metal quality was observed in these areas in the control ingots. It has been demonstrated that the combined method of external influence, which integrates heating and metal stirring, improves the quality of steel ingots by significantly enhancing their physical homogeneity.