Comparative analisys of the quality indices of the 110G13L steel produced with various inoculants and deoxidizing agents
Problem Statement (Relevance). This paper describes special characteristics and potential benefits of the aluminum-containing diffusion deoxidizer RDA, which was developed to deliver a broad range of additional performance properties in castings and help shorten the reduction time in the case of the 110G13L steel. The relevance of this research is demonstrated in the case study of Mikhailovsky GOK, for which the adoption of the diffusion deoxidizer resulted in the economic benefit of 3 million rubles. Objectives. The aim of this research was to find ways to optimize the reduction process of the 110G13L steel. Methods Applied. The research heavily relied on statistical analysis method. Thus, all the results were analysed with the help of the STATISTICS & ANALISIS computer programme. The tests were run with an alpha level of 0.5. There were determined arithmetic averages for the chemical composition of metal and slags, as well as their variation indices that characterize their stability. The less the variations fluctuate around an average, the more stable the average is. The range of variations defined the stability of the property. The variation coefficient best describes the homogeneity of characteristics because it indicates the relative measure of fluctuations. It can be defined as a ratio of the standard deviation to the arithmetic average. Originality. A special feature of the new deoxidizer is that all of its components are present in a finely dispersed state. A drastic increase in the specific surface of the particles contained in the deoxidizer would lead to a significantly more intense reduction process, which enables a dramatically shorter and more efficient reduction process. Another method was applied to intensify deoxidation, and namely - rapid application of the deoxidizer over the slag surface. This effect is achieved due to the sodium and potassium compounds, which make the mixture flowable and help it spread rapidly across the slag surface. Findings: The article contains a comparison between the L-Cast ® 5.3 inoculant and the aluminum-containing high-dispersion diffusion deoxidizer RDA (the latter was developed by Metallurg LLC, the Smolensk Regional Office of the Russian Foundry Association) and their refining efficiencies. The statistical analysis of experimental data showed a higher efficiency of RDA compared with L-Cast ® 5.3. Lower concentrations of MnO and FeО were observed in the slags produced with the aluminum-containing high-dispersion diffusion deoxidizer RDA. The average MnO content decreased by 5% - to 3.54 when the RDA deoxidizer was applied versus a 3.72% concentration resulting from the application of L-Cast® 5.3. There was a more drastic decrease in the average concentration of FeO - by 18% to 0.66% versus a 0.78% concentration resulting from the use of L-Cast®5.3 as a deoxidizer, which is extremely important as the FeO concentration is critical for slags. It refers to the fact that MnO dissolves FeO creating very strong conglomerates, which, when heat is applied, are hard to dissolve and tend to stay at the grain boundaries. The less FeO concentration there is in the slag the thinner the grain boundaries are and the better the performance of steel is. Consequently, RDA is a more efficient deoxidizer for slag than L-Cast® 5.3. The increase of the residual aluminium in steel from 0.0044% to 0.04752% indicates a higher deoxidation degree of the slag, which led to a decrease in the oxygen content. As a result, pourers pointed out a better fluidity and moldability of molten steel. Practical Relevance. Due to the results of this research, the Mikhailovsky GOK foundry was able to adopt the RDA diffusion deoxidizer for application with the 110G13L steel seeing the economic benefit of 3 million rubles.