THE INFLUENCE OF STRAIN-INDUCED DEFECTS ON PHASE AND ELEMENTAL COMPOSITION OF HARDENED SURFACE LAYERS OF AUSTENITIC STAINLESS STEEL FORMED DURING ION-PLASMA TREATMENT

  • Valentina Aleksandrovna Moskvina Institute of Strength Physics and Materials Science of Siberian Branch of Russian Academy of Sciences
  • Elena Gennadyevna Astafurova Institute of Strength Physics and Materials Science of Siberian Branch of Russian Academy of Sciences
  • Kamil Nurullaevich Ramazanov Ufa State Aviation Technical University
  • Galina Gennadyevna Maier Institute of Strength Physics and Materials Science of Siberian Branch of Russian Academy of Sciences
  • Sergey Vladimirovich Astafurov Institute of Strength Physics and Materials Science of Siberian Branch of Russian Academy of Sciences
  • Marina Yurievna Panchenko Institute of Strength Physics and Materials Science of Siberian Branch of Russian Academy of Sciences
  • Evgeny Vasilyevich Melnikov Institute of Strength Physics and Materials Science of Siberian Branch of Russian Academy of Sciences
  • Elena Andreevna Zagibalova National Research Tomsk Polytechnic University
Keywords: austenitic stainless steel, cold rolling, grain-subgrain structure, crystal structure defects, dislocations, ion-plasma treatment, X-ray diffraction, Auger-electron spectroscopy, solid-solution strengthening, precipitation hardening

Abstract

Austenitic stainless steels are demanded alloys in modern industry due to their physical and mechanical characteristics. Concurrently, they are not devoid of weaknesses – strength properties do not meet the performance requirements for their use in the manufacture of essential components.

One of progressing way to solve this problem is ion-plasma saturation with interstitials (nitrogen and carbon) of materials surface. In this paper, authors investigated the influence of pre-deformation microstructure with different density of deformation-associated defects on phase and elemental composition of surface layers formed during ion-plasma treatment in stable austenitic stainless steel (316L-type). It was shown that thermal-mechanical treatment in two regimes facilities to the formation of grain-subgrain structure submicrometer scale in specimens, in which main differences lie in the density of deformation defects and fraction of low-angle boundaries. It has been shown that during ion-plasma treatment in the mixture of gases (Ar + N2 + C2H2) at 540 °С (12 hours) of stable austenitic stainless 316L-type steel independently of initial microstructure (deformation-induced grain-subgrain with high density of defects or annealed grain-subgrain) in specimens surface layers with the same phase compositions were formed – supersaturated with nitrogen and carbon austenite and ferrite (Fe-γN, C and Fe-αN, C), nitrides and carbonitrides Cr(N, C), Fe4(N, C). The high density of non-equilibrium crystal defects promoted to the intensive saturation of the surface layers with nitrogen and carbon in austenitic stainless steel. The developed defective grain-subgrain structure in specimens contributes accumulation of interstitials (nitrogen and carbon) during ion-plasma treatment in the surface layer (≈ 5 μm) and suppression of bulk diffusion of carbon compared to the annealed grain-subgrain structure. The experimental results provide support for significant role of deformation-assisted well-developed microstructure in accumulation and bulk diffusion of interstitials under ion-plasma treatment of austenitic stainless steel.

Author Biographies

Valentina Aleksandrovna Moskvina, Institute of Strength Physics and Materials Science of Siberian Branch of Russian Academy of Sciences

postgraduate student, junior researcher

Elena Gennadyevna Astafurova, Institute of Strength Physics and Materials Science of Siberian Branch of Russian Academy of Sciences

Doctor of Sciences (Physics and Mathematics), Associate Professor, leading researcher

Kamil Nurullaevich Ramazanov, Ufa State Aviation Technical University

Doctor of Sciences (Engineering), Professor

Galina Gennadyevna Maier, Institute of Strength Physics and Materials Science of Siberian Branch of Russian Academy of Sciences

PhD (Physics and Mathematics), researcher

Sergey Vladimirovich Astafurov, Institute of Strength Physics and Materials Science of Siberian Branch of Russian Academy of Sciences

PhD (Physics and Mathematics), senior researcher

Marina Yurievna Panchenko, Institute of Strength Physics and Materials Science of Siberian Branch of Russian Academy of Sciences

postgraduate student, junior researcher

Evgeny Vasilyevich Melnikov, Institute of Strength Physics and Materials Science of Siberian Branch of Russian Academy of Sciences

junior researcher

Elena Andreevna Zagibalova, National Research Tomsk Polytechnic University

student

Published
2019-09-30
Section
Technical Sciences