SPECIFICS OF STRUCTURAL IRON STRUCTURE FORMATION AT THE CONTROLLED ROLLING AND THERMAL AFTERTREATMENT
The structure and properties of plate rolled high strength structural steel of different composition were studied after the controlled rolling. There is shown that a decrease of temperature of the deformation completion leads to an increase of strength properties, an increase of the structure streaking degree being observed thereat. There is described a mechanism of the structure streaking formation at a low temperature controlled rolling. It is shown that the reason of the structure streaking is "treatment liquation" - a specific chemical inhomogeneity formed in the process of rolling at the temperatures lower then the temperature recrystallized threshold. It has been found out that a dark streak pattern in steels after the controlled rolling can remain at further production modes. There has been studied the process of austenitizing steel with a ferrite pearlitic streaking. It was determined that in heating up to 900°С austenite still has "treatment liquation" preserved which becomes apparent in the form of streaks of a higher etching, these streaks being located at the place of the previous perlitic streaks.