Study of effect of hardening cooling rate on microstructure of 12Kh17G9AN4-Sh steel

Abstract

Currently, sheet rolling made of stainless austenitic steels are in demand and are widely used in various fields of industry and the national economy. It is used for the manufacture of welded structures, products for the aviation and food industries, as well as other industries. The main requirement for this type of sheet rolled is corrosion resistance and good plastic properties. Technological operations in the production of sheet rolling from corrosion-resistant steels of the austenitic class are selected in such a way as to ensure maximum resistance against corrosion, and the plastic properties are ensured by a homogeneous single-phase austenitic structure. Chromium is the main alloying element of corrosion resistant steels. With increasing chromium content, the corrosion resistance of steel increases. For maximum corrosion resistance, the chromium in the steel must be dissolved in the austenite. The precipitation of its carbides from the solid solution during cooling is an extremely undesirable process, since this will lead to a decrease in the percentage of chromium in austenite and a decrease in the resistance to intercrystalline corrosion. Insufficient cooling during quenching can lead to the precipitation of chromium carbides and deterioration of the corrosion resistance of the steel. The paper presents the results of a study of the effect of various cooling media (air, water) during quenching of thin-sheet rolled products made of corrosion-resistant steel 12Cr17Mn9NNi4-SH. An X-ray phase structural analysis was carried out, the thermodynamically equilibrium phase composition was calculated, and the microstructure and microhardness of steel were studied. Using chemical analysis, the distribution of alloying elements over the cross section of austenite grains was estimated. To assess the obtained values of microhardness, a statistical analysis was carried out.