Features of structure and mechanical properties formation in shaped rolled products made of 09G2S steel in accelerated water cooling process

Abstract

The article provides an analysis of methods for strengthening structural shapes in a stream of section mills, a series of active experiments was carried out, and a calculation of predictive regression equations for the dependence of mechanical properties and microstructure indicators on the geometry of profile dimensions and technological parameters of cooling. An algorithm has been developed for iterative refinement of the forecast accuracy using such equations, which provides the minimum error in determining the specified characteristics. Metal microstructure at various modes of accelerated cooling in calm water of shaped rolled in the flow of a section mill confirms the patterns of structure formation and corresponds to the theory and practice of science of metals and heat treatment of metals. The developed techno logy of accelerated water cooling provides for shaped rolling increase in strength to a class of 600 MPa and higher for a wide assortment of structural shapes and for critical purposes for pipe and ship-car building. The use of accelerated cooling in calm water of shaped rolled gives a significant economic effect (80-100 USD per 1 ton of rolled steel) instead of using microalloying steel with elements such as vanadium and niobium, which reduce the size of the austenitic and then the real grain of the metal and thereby increase the yild point and its relation to the ultimate tensile strength, providing substantial strengthening of rolled products. As a result, an efficient technology have been developed for thermal hardening of structural shapes in the flow of a section mill.