PHYSICAL CORROSION PROCESSES IN FERRITE-PEARLITIC STEELS

Abstract

Background Results of physical corrosion of ferrite-pearlitic steels have been studied. The growth of grains leads to a deterioration in the physical and mechanical properties of steel, is observed with prolonged aging of the steel at certain temperatures: pre-eutectoid steels or hypereutectic steels, with the growth of austenite grains. Upon cooling, a coarse-grained ferrite-pearlite structure forms. Steels with such a structure have low mechanical characteristics. Aims and Objectives To study the influence of the physical influence of the medium on ferrite-pearlitic steels, the mechanisms and processes occurring inside the steel during physical corrosion, the process of destruction of steel caused by decarburization, carburizing, phase transitions, the release of carbides, hydrogen, water and methane on defects, nonmetallic inclusions and grain boundaries and also growth of grains and the formation of eutectic alloys and the decomposition of a solid solution. Results Various manifestations of physical corrosion of ferrite-pearlitic steels have been revealed, which lead to a deterioration in the physicomechanical properties of steel. Vanadium (catastrophic) corrosion is represented. It is noted that the Fe - V2O5 system forms at eutectic alloy (its melting temperature is lower than the melting point of vanadium oxide and steel), which leads to the melting of the metal structure. It is noted that when a number of refineries are operating, the steel is ignited, leading to an increase in strength and a decrease in ductility. This leads to an increase in the probability of brittle failure of the device. In the interaction of oxygen with steel, along with the oxidation of iron, oxidation of the carbon that forms part of the cementite occurs. Decarburization leads to a reduction in the strength of the steel completely or its surface layers. The article presents hydrogen brittleness of steel or hydrogen corrosion, which occurs in an atmosphere of molecular hydrogen at a temperature above 200 °C. Also a scheme for the formation of carbon-bearing corrosion, which occurs when a metal interacts with carbon monoxide at high pressures and elevated temperatures as a result of a reversible reaction, is shown.