The influence of heat treatment modes on structure and corrosion properties of 14Kh17N2 steel

Issues of ensuring the stability of the structural state and mechanical properties are very relevant for production when processing products, assessing quality and extending service life. The article presents studies of the influence of changes in the structure resulting from the use of various heat treatment modes using the example of heat-resistant, corrosion-resistant steel 14Kh17N2, which belongs to the martensitic-ferritic class steels, containing in its structure, in addition to martensite, at least 10 % ferrite. It has the greatest corrosion resistance after hardening with high tempering. Steel 14Kh17N2 is very complex in technological terms. The presence of large quantities of δ-ferrite in the structure of this steel has a harmful effect on the course of technological processes: it worsens the deformability of steel and sharply reduces the plasticity properties (especially impact strength) when testing samples in the tangential or transverse direction, and increases the anisotropy of mechanical properties. A relationship has been established between the amount of δ-ferrite and the carbide phase precipitated at its boundaries with the mechanical properties of steel. It has been shown that with increasing quenching temperature, the amount of δ-ferrite changes slightly, and the amount of the carbide phase decreases. Corrosion tests of samples in an aqueous solution of potassium thiocyanate (KSCN) with sulfuric acid (H₂SO₄) after various heat treatment modes showed that with a decrease in the amount of chromium carbides released at the boundaries of the δ-phase, the ratio of the amount of electricity (Sk/Sa) decreases. the depth of corrosion does not depend on the amount of δ-ferrite and chromium carbides. On the surface of all samples, in the areas of the boundary between the δ-phase and tempered troostite, traces of corrosion destruction of varying depths are visible.State assignment of the Institute of Applied Physics RAS for fundamental scientific research for 2024–2026. FFUF-2024-0031. No. NIOKTR 1023032800130-3-2.3.2.