Open AccessSPECIFIC FEATURES OF STRUCTURAL-PHASE TRANSFORMATIONS AND HARDENING DURING SHEAR DEFORMATION UNDER PRESSURE OF HIGH-NITROGEN STEEL WITH AUSTENITIC-FERRITIC STRUCTURE OF METAL MATRIX
Author(s) -
S. N. Luchko,
AUTHOR_ID,
A. V. Makarov,
Е. Г. Волкова,
AUTHOR_ID,
AUTHOR_ID
Publication year - 2021
Publication title -
frontier materials and technologies
Language(s) - English
Resource type - Journals
eISSN - 2782-6074
pISSN - 2782-4039
DOI - 10.18323/2782-4039-2021-4-39-47
Subject(s) - austenite , materials science , metallurgy , hardening (computing) , pearlite , ferrite (magnet) , carbide , nitride , composite material , microstructure , layer (electronics)
The increased anticorrosive, strength, tribological, and physical characteristics are the specific features of steels with high nitrogen content. Searching for the ways to strengthen high-nitrogen steels is a promising area of contemporary metal science. Heat treatment is one of the methods of hardening nitrogen steels as a result of precipitation hardening with nitride particles. The authors studied the influence of short-term high-temperature aging and large plastic deformations implemented by shear under the pressure of 8 GPa (SP method) on Bridgman anvils (three revolutions of anvils with the rotation velocity of 0.3 rev/min) at room temperature on the structural-phase transformations and micromechanical properties of the 08H22GA1.24 high-nitrogen steel with the mixed γ (austenite) + (ferrite) metal matrix structure. The study identified that aging (0.5 h) at the temperature of 650 °С of steel quenched at the temperature from 1180 °С causes the formation of the mixed austenitic-ferritic structure of metal matrix in the ratio of 50 vol. % of and 50 vol. % of α and the release of extended secondary Cr2N chromium nitrides, together with ferrite interlayers forming the areas with the pearlite-like structure. These areas cause the increased microhardness of steel with the austenitic-ferritic matrix structure (385±8 HV 0.025) compared to one of steel aged at the temperature of 550 °С (0.5 h) and having an austenitic matrix structure strengthened with secondary CrN nitrides (364±8 HV 0.025). The SP deformation of steel aged at the temperature of 650 °С (0.5 h) with the initial ++Cr2N structure leads to →ʹ transformation and the formation of submicro- and nanocrystalline structures. It causes the effective strength improvement of steel (up to 900±29 HV 0.025) and the growth of resistance to elastoplastic deformation compared to aged at the temperature of 550 °C (0.5 h) condition.