The influence of rolling at subcritical temperatures on the low-carbon steel structure and properties formation

Abstract

Problem. In practice, the rolling of a low-carbon steel sheet due to significant heat losses ends in the austenite – ferrite two-phase structure region, which leads to the metal heterogeneous structure formation, that decreases the sheet steel properties of the and its ability to be drawn.
 Adverse temperature conditions characteristic of traditional hot rolling technology can be prevented by metal processing in the single-phase ferrite structure region below the critical point Ar1. Rolling of a thin sheet in the subcritical temperature range will ensure obtaining a uniform metal structure, which determines the level of its mechanical properties, as well as the quality of stamped parts
 Goal. The purpose of the work is study the rolling modes influence at subcritical temperatures on the low-carbon steel structure and properties formation.Methodology. The microstructure of 08ps steel samples was studied using a metallographic and electron microscope JSM-840 with a "Link-860/|500" microanalysis system, the 08ps steel samples cross-section fine structure was studied using an electron microscope JEM - 200Сx. The metal mechanical properties complex was determined by standard tensile test methods.Results. The 08ps steel structure and properties after rolling at subcritical temperatures were studied. The comparative analysis of the fine structure of the initial blank and deformed samples of low-carbon steel was carried out. It was established that changes are observed in the structure of the deformed samples and the initial blank, which indicate the polygonization and recrystallization processes implementation and do not provide the of metal mechanical properties level provided for by DSTU 2834-94.Originality. Тhe thin structure of a 08ps steel sheet deformed in the subcritical temperature range with air cooling was studied. The development differs in the temperatures of the beginning and end of rolling, as well as the cooling rate in the post-deformation period. It allows to expand theoretical ideas about the patterns of 08ps deformed steel structure formation and to use them in practice. Practical value. The results of the work can be applied in determining rational processing modes, which involve rolling at subcritical temperatures, to increase the complex metal properties and obtain high-quality parts by cold stamping.