Features of the production of high-quality carbon cast steel in induction crucible furnaces of small capacity

Abstract

A rational technology was developed for the production of high-quality cast carbon steel for small castings in small-capacity induction crucible furnaces.
In order to determine the carbon and sulfur content, instead of expensive spectral instruments, the cost of which significantly increases the cost of finished products, a metallographic method based on method L (GOST1778-70) for quantitative evaluation of the structural components of steel is proposed. Silicon content was determined using a specially developed device based on the TEMF method.
In order to implement metallographic methods of analysis and with the aim of the rapid manufacture of specimens, a mini laboratory was developed and produced, which consists of a small-size cutting machine, a single-spindle grinding and polishing machine with a set of abrasive wheels of different grain sizes and felt polishing discs impregnated with diamond paste, a simplified metallographic microscope MMU-3 with a video camera, a vacuum sampler for sampling liquid metal during smelting process, a device for determining silicon content in steel.
Several methods of structural section calculation were tested, but the simplest and proven linear method developed at the «Machines and technology of foundry» Department of National University «Zaporizhzhia Polytechnic» was adopted. The readings of temperature measurements by thermocouple and radiation pyrometers were compared. The latter do not change the solidification conditions of the castings, and the measurement speed is not inferior to thermocouples. Calculation and preparation of the charge were carried out by standard methods, but high precision appliances were used. The studies carried out allowed us to obtain accurate data on the structure and quality indicators of blanks or castings.
Testing of the developed technology confirmed the rational consumption of charge materials, guaranteed chemical composition and stable quality indicators of finished products.