Успехи физики металлов (Sep 2023)
Influence of Modification on the Characteristics of Reinforcing Steels Intended for Reinforced Concrete Structures
Abstract
We review and analyse the reasons of destabilizing the chemical composition and mechanical characteristics reinforcing low-carbon steels and present ways to solve these problems. As determined, both the instability of the chemical composition and the non-metallic inclusions of an elongated and acute-angled shape, containing an excessive amount of gas and other impurities, reduce the service life of the finished metallurgical product and lead to a deterioration in the quality of the finished product. As established and proven, one of the ways to maximize the chemical-composition stabilization and to improve mechanical characteristics, as well as the quality of the reinforcement, is the steel-melts’ processing with multifunctional-action modifiers. As determined, the St1kp steel, like other low-alloy steels, is a multicomponent system consisting of 17 or more components. Each of the impurities, as well as deoxidizing modifier elements (Al, Ti, Mg), can change significantly the composition of non-metallic inclusions, the main matrix, cementite, grain size, mechanical characteristics, and their stability. As established, after modification, the St1kp-steel grain structure is almost 2 times finer, after which it can be asserted safely that such a material can last longer. As revealed, all mechanical-characteristics’ parameters of the modified metal met the requirements of the State Standards (DSTU) 2770-94 and exceed the serial ones. This is especially important for reinforced concrete structures, since the insufficient level of mechanical characteristics and their instability cannot guarantee the reliability and durability of their operation. As noted, during the solidification of the modified ingot, mainly volumetric crystallization takes place, and not heat-sink-oriented crystallization, as for serial metal. The predominant mechanism of bulk crystallization is one of the main reasons for the stabilization of the chemical composition and the increase in the mechanical-characteristics’ level of steels under the complex influence of alloying components and harmful impurities of steel both serial and modified with multifunctional modifiers of melts. As proved in the work, after modification, the morphology of non-metallic inclusions is significantly improved. As a result, the quality of the finished reinforcement is significantly increased.
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