Abstract
Problem Statement: As part of the comprehensive project of creating a hi-tech production process, which is carried out by Nosov Magnitogorsk State Technical University together with Termodeform-MGTU LLC at the request of Magnitogorsk Iron and Steel Works, a process is being developed for the production of nanostructured flat rolled products having a unique combination of mechanical properties and capable of substituting similar imported products. Objectives: The objective is to look at how the chemical composition and the heat treatment conditions effect the hardness and the impact strength of nanostructured high-strength rolled sheet steel. Methods Applied: With the help of the Termodeform-MGTU laboratory facilities, a number of ingots were produced, which had various chemical compositions and which were later exposed to hot deformation and different modes of heat treatment. After the heat treatment, a number of samples were prepared from the sheets for hardness and impact testing. The results of the mechanical tests were then analysed for statistics. Originality: The originality of this work includes the mathematical dependences established which show how the chemical composition and the heat treatment conditions can effect the hardness and the impact strength in high-strength rolled sheet steel. Findings: Following the statistical analysis of the experimental data, equations were obtained that show how the chemical composition and the heat treatment conditions effect the hardness and the impact strength of high-strength rolled sheet steel. Also, it was found that the temperature range of 250 to 400 °C does not prove to be a good tempering temperature for high-strength Cr-Ni-Mo-V steel with 0.3% of carbon as it can lead to constant temper brittleness. Practical Relevance: The mathematical dependences established enable to create new or improve the current high-strength rolled sheet steel production processes.
Keywords
High-strength steel, heat treatment, hardness, toughness, statistical analysis.
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