2018-Sustainable Industrial Processing Summit
SIPS2018 Volume 4. Mamalis Intl. Symp. / Advanced Manufacturing
| Editors: | F. Kongoli, A. G. Mamalis, K. Hokamoto |
| Publisher: | Flogen Star OUTREACH |
| Publication Year: | 2018 |
| Pages: | 352 pages |
| ISBN: | 978-1-987820-88-1 |
| ISSN: | 2291-1227 (Metals and Materials Processing in a Clean Environment Series) |
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Effect of Deformation on Phases Formation and Properties of Surface Layers in Fe-based Alloys Under Diffusion of N and C
Sergii Sidorenko1; Lesya Demchenko2; Anatoliy Titenko3; Tie-Zhen Ren4;1IGOR SIKORSKY KYIV POLYTECHNIC INSTITUTE, Kyiv, Ukraine; 2NATIONAL TECHNICAL UNIVERSITY OF UKRAINE "IGOR SIKORSKY KYIV POLITECHNIC INSTITUTE", Kyiv, Ukraine; 3INSTITUTE OF MAGNETISM, NAS OF UKRAINE, Kyiv, Ukraine; 4HEBEI UNIVERSITY OF TECHNOLOGY, Tianjin, China;
Type of Paper: Regular
Id Paper: 178
Topic: 48
Abstract:
The diffusion saturation of iron-based alloys with nitrogen and carbon is widely used in industry for increasing strength, hardness, wear, and corrosion resistance of metal products operating in extreme environments. Inexhaustible and unrealized potentialities of such treatments are unconvered when applying it under strain and stress condition [1]. In this context, the question at hand is to clarify diffusion and strengthening mechanisms of strained alloys under chemical-thermal treatment by N and C.
The effect of preliminary plastic deformation from 5 to 70 % with the step 5 and 10 % on nanostructured diffusion layers formation, kinetics of their growth, chemical and phase composition, and microhardness were studied in <i>α</i>-Fe and iron-based (Fe-Cr, Fe-Ti, Fe-Cr-Ti, Fe-Ni) alloys doped with Cr, Ti or Ni in the amount of (0.5-2.0wt.%) after the saturation with nitrogen and carbon from a gas mixture of ammonia and propane-butane, at 853 K for 0.5; 1; 2; 4; 6; 8 hours [2].
As a result of the investigation, it was found that the diffusion layer is a combination of surface layers of different nanosized nitride phases (<i>ξ</i>-, <i>ε</i>-, <i>γ'</i>-), nanostructured (<i>γ'</i> + <i>ε</i>-) — eutectoid layer and a nanostructured zone of internal saturation (<i>α</i>- phase). Deformation considerably affects the phase formation, structure, microhardness, and thickness of nitrided layers. Microhardness test of the nitrided layers led to the discovery of narrow intervals of deformations of 3-8 % and 20-30 %, in which there was considerable rise (about double) of the surface diffusion layer's microhardness in <i>α</i>-Fe after nitriding. The high microhardness of the diffusion layers results from the formation of nanosized <i>ε</i>- and <i>γ'</i>- nitrides. The concentration distribution of N and C and the depth of their penetration also depends on the deformation degree, correlated with the microhardness test results.
The possible mechanisms of diffusion and mass-transfer of interstitials (N and C) in deformed alloys are discussed, and in particular, the possibilities of the interstitials mass-transfer with mobile dislocations in deformed alloys according to the dislocation-dynamic mechanism are considered [3].
Keywords:
Nanotechnology/Nanomaterials manufacturing; Powder production and processing;References:
[1] S.I. Sidorenko, V.G. Tinyayev, L.D. Demchenko, Yu.P. Sheiko, Met. Phys. Adv. Tech. 18 (2000) 1383-1392[2] L. Demchenko, S. Sidorenko, V. Tinyaev, Defect and Diffusion Forum 216-217 (2003) 87-92
[3] L. Demchenko, S. Sidorenko, Defect and Diffusion Forum 309-310 (2011) 155-160