Obrabotka Metallov 2015 No. 3

ОБРАБОТКА МЕТАЛЛОВ № 3 (68) 2015 105 МАТЕРИАЛОВЕДЕНИЕ OBRABOTKAMETALLOV (METAL WORKING AND MATERIAL SCIENCE) N 3(68), July – September 2015, Pages 99–106 Structural-phase state and cyclic life of high-chromium steel 40Kh13 processed by intense flows of nitrogen ions Kukareko V.A. , D.Sc. (Physics and Mathematics), Associate Professor, Head of Center, e-mail: v_kukareko@ mail.ru , csimt@tut.by The State Scientific Institution “Joint Institute of Mechanical Engineering of the National Academy of Sciences of Belarus”, Centre of Structural Research and Tribo-Mechanical Test of Materials, 12 Akademicheskaya str., Minsk, 220072, Republic of Belarus Abstract The effect of ion-beam nitriding at temperature 670 and 770 K on the structure, phase composition and cyclic durability (fatigue resistance) of high-chromium martensitic steel 40Kh13 is considered. It is shown that the nitrided layer on the steel treated at 670 K contains particles of nitride phases such as e –(Fe,Cr) 2–3 N, g′ –(Fe,Cr) 4 N, a ″– (Fe,Cr) 8 N and the solid solution of nitrogen in martensite. Treatment of the 40Kh13 steel at 770 K leads to formation of the nitrided layer containing CrN nitride particles. The occurrence of compressive stresses the nitrided layers is registered. The highest compressive stresses of 780 MPa are located in the steel 40Kh13 surface layer treated with nitrogen ions at 670 K. It was found that the steel processing by intensive flows of nitrogen ions effectively increases its’ micro-hardness and resistance to fatigue failure in the field of high-cycle fatigue. The most efficient increase in the number of cycles to failure is recorded after the nitrogen ion beam processing of the steel at 670 K. The fatigue resistance of the steel treated at 670 K increases up to 850 MPa. It is concluded that the cycle life is greatly influenced by the level of compressive stresses in the surface layers. The highest levels of compressive stress and cyclic dura- bility is achieved by ion processing of the steel at 670 K, which provides both the formation of nitrides and a high concentration of dissolved nitrogen in the matrix phase. Keywords: steel 40Kh13, ion-beam nitriding, phase composition, the cyclic durability. DOI: 10.17212/1994-6309-2015-3-99-106 References 1. Klesnil M., Lukas P. Fatigue of metallic materials. Materials science monographs . Vol. 71. 2nd rev. ed. Am- sterdam, Elsevier Science Publ., 1992. 270 p. ISBN-10: 0444987231. ISBN-13: 978-0-444-98723-5 2. Finkel’ V.M. Fizicheskie osnovy tormozheniya razrusheniya [Physical basis of braking failure]. Moscow, Met- allurgiya Publ., 1977. 360 p. 3. Davidson D.L., Lankford J. Fatigue crack growth in metals and alloys: mechanisms and micromechanics. International Materials Reviews , 1992, vol. 37, iss. 1, pp. 45–76. doi:  http://dx.doi.org/10.1179/imr.1992.37.1.45 4. Byeli A.V., Kukareko V.A., Pateyuk A. Inzheneriya poverkhnostei konstruktsionnykh materialov kontsen- trirovannymi potokami ionov azota [A surface engineering structural materials with concentrated streams of nitrogen ions]. Minsk, Belorusskaya nauka Publ., 2007. 244 p. ISBN 978-985-08-0793-9 5. Williamson D.L., Ozturk O., Glick S., Wei R., Wilbur P.J. Microstructure of ultrahigh-dose, nitrogen – im- planted iron and stainless steel. Nuclear Instruments and Methods in Physics Research. Section B: Beam Interactions with Materials and Atoms , 1991, vol. 59–60, pt. 2, pp. 737–741. doi: 10.1016/0168-583X(91)95693-8 6. Wei R., Vajo J.J., Mattosian J.N. ,Wilbur P.J., Davis J.A., Williamson D.L., Collins G.A. A comparative study of beam ion implantation, plasma ion implantation and nitriding of AISI 304 stainless steel. Surface and Coatings Technology , 1996, vol. 83, iss. 1–3, pp. 235–242. doi: 10.1016/0257-8972(95)02825-0 7. Kukareko V.A., Byeli A.V. Dose rate and microstructure of nitrogen ion-implanted chromium steels. Surface and Coatings Technology , 2000, vol. 127, iss. 2–3, pp. 174–178. doi: 10.1016/S0257-8972(99)00654-4