Determination of static fracture toughness of coarse-grained and ultrafine-grained materials by the depth of the plastic zone under the fractures surface

G.V. Klevtsov, R.Z. Valiev, N.A. Klevtsova, I.N. Pigaleva show affiliations and emails
Received 19 August 2020; Accepted 14 October 2020;
This paper is written in Russian
Citation: G.V. Klevtsov, R.Z. Valiev, N.A. Klevtsova, I.N. Pigaleva. Determination of static fracture toughness of coarse-grained and ultrafine-grained materials by the depth of the plastic zone under the fractures surface. Lett. Mater., 2021, 11(1) 45-49
BibTex   https://doi.org/10.22226/2410-3535-2021-1-45-49

Abstract

The relation of the coefficient n in the equation hmax=1/nπ ((K1C (KC ))/σ0.2 )2 (where hmax is the maximum depth of the plastic zone under the fracture surface) with the criterion of the local stress state hmax/t for CG and UFG materials with BCC, FCC and HCP lattice when testing samples for static crack resistanceIn the practice of diagnostics of emergency failure of structures or machine parts, there are cases when information is needed on the fracture toughness (K1C or KС) of the material of products, the dimensions and configuration of which do not allow the fabrication of samples for testing the material for K1C according to the standard GOST 25.506-85. On an example of a large group of materials with bcc, fcc and hcp lattices, the relationship of the fracture toughness (K1C or KC) of materials with the yield strength, hardness and elongation is considered. It is shown that the fracture toughness of materials both in coarse-grained (CG) and ultrafine-grained (UFG) states is ambiguously related to these mechanical characteristics of materials. Therefore, the fracture toughness of materials cannot be determined by calculation based on the above strength and plastic properties. In this paper, we propose a method for determining fracture toughness of CG and UFG materials by the maximum depth of the plastic zone under the fracture surface (hmax) of fractured specimens, structures, or machine parts. The depth of the plastic zones under the fracture surface was determined by the X-ray method. If the destruction occurred in the plane stress (PS) condition or in the transition region from plane deformation to plane stress state (PD←→PS), then the depth of the slightly deformed macro zone (hy) was taken as hmax. Using the example of a large group of materials with bcc, fcc and hcp lattices, it has been shown that it’s possible in principle to determine the fracture toughness of CG and UFG materials with different types of crystal lattice using the plastic zone depth under the fractures surface.

References (21)

1. M. Srinivas, G. Malakondaiah, R. W. Armstrong, P. Rama Rao. Acta Metall. Mater. 39 (5), 807 (1991). Crossref
2. I. Sabirov, R.Z. Valiev, I.P. Semenova, R. Pippan. Metallurgical and materials transactions A. 41, 727 (2010). Crossref
3. C. F. Shih. J. Mech. Phys. Solids. 29 (4), 305 (1981). Crossref
4. M. Srinivas, G. Malakondaiah, P. RamaRao. Acta Metall. Mater. 41, 1301 (1993). Crossref
5. R. Boyer, G. Welsch, E. W. Collings. Materials Properties Handbook: Titanium Alloys. USA, ASM Internationa (1998) 1048 p.
6. G. V. Klevtsov, E. V. Bobruk, I. P. Semenova, N. A. Klevtsova, R. Z. Valiev. Strength and fracture mechanisms of bulk nanostructured metallic materials. Ufa, UGATU (2016) 240 p. (in Russian) [Г. В. Клевцов, Е. В. Бобрук, И. П. Семенова, Н. А. Клевцова, Р. З. Валиев. Прочность и механизмы разрушения объемных наноструктурированных металлических материалов. Уфа, УГАТУ (2016) 240 с.].
7. R. Z. Valiev, A. P. Zhilyaev, T. G. Langdon. Bulk Nanostructured Materials: Fundamentals and Applications. USA, TMS, WILEY (2014) 440 p. Crossref
8. A. J. McEvily. Metal Failures: Mechanisms, Analysis, Prevention. New York, Wiley & Sons (2002) 324 р.
9. G. V. Klevtsov, L. R. Botvina, N. A. Klevtsova, L. V. Limar. Fractodiagnosis of the fracture of metallic materials and structures. Moscow. MISiS (2007) 264 p. (in Russian) [Г. В. Клевцов, Л. Р. Ботвина, Н. А. Клевцова, Л. В. Лимарь. Фрактодиагностика разрушения металлических материалов и конструкций. Москва, МИСиС (2007) 264 с.].
10. F. Wetscher, R. Stock, R. Pippan. Fracture Processes in Severe Plastic Deformed Rail Steels. Proceedings of the 16th European Conference on Fracture. Alexandropoulos, Greece (2006) р.1.
11. D. Taylor. Engineering Fracture Mechanics. 75, 1696 (2008). Crossref
12. K. Hellan. Introduction to Fracture Mechanics. Moscow, Mir (1988) 364 p. (in Russian) [K. Хеллан. Введение в механику разрушения. Москва, Мир (1988) 364 с.].
13. L. C. Moroz. Mechanics and physics of deformation and fracture. Leningrad, Mashinostroyeniye (1984) 224 p. (in Russian) [Л. С. Мороз. Механика и физика деформаций и разрушения. Ленинград, Машиностроение (1984) 224 с.].
14. G. V. Klevtsov, L. R. Botvina, N. A. Klevtsova, A. P. Fot. Metal Science and Heat Treatment. 52 (7), 396 (2010). Crossref
15. G. V. Klevtsov, R. Z. Valiev, N. A. Klevtsova, I. P. Semenova, I. N. Pigaleva, M. L. Linderov. Letters on Materials. 10 (1), 16 (2020). (in Russian) [Г. В. Клевцов, Р. З. Валиев, Н. А. Клевцова, И. П. Семенова, И. Н. Пигалева, М. Л. Линдеров. Письма о материалах. 10 (1), 16 (2020).]. Crossref
16. R 50-54-52/2-94. Calculations and strength tests. Method of X-ray structural analysis of fractures. Determination of the fracture characteristics of metallic materials by the X-ray method. Moscow, VNIINMASH Gosstandart of Russia (1994) 28 p. (in Russian) [Р 50-54-52/2-94. Расчеты и испытания на прочность. Метод рентгеноструктурного анализа изломов. Определение характеристик разрушения металлических материалов рентгеновским методом. Москва, ВНИИНМАШ Госстандарта России (1994) 28 с.].
17. A. Hohenwarter, R. Pippan. Acta Materialia. 61, 2973 (2013). Crossref
18. А. Hohenwarter, R. Pippan. Fracture toughness and fatigue crack propagation measurements in ultrafine grained iron and nickel. USA, TMS (2008) 183 p.
19. L. R. Botvina, M. I. Alymov, M. R. Tutin, T. B. Petersen, S. A. Tihomirov, N. A. Solovev. Russian Nanotechnologies. 2 (1-2), 106 (2007). (in Russian) [Л. Р. Ботвина, М. И. Алымов, М. Р. Тютин, Т. Б. Петерсен, С. А. Тихомиров, Н. А. Соловьев. Российские нанотехнологии. 2 (1-2), 106 (2007).].
20. G. V. Klevtsov. Factory laboratory. 57 (3), 32 (1991). (in Russian) [Г. В. Клевцов. Заводская лаборатория, 57 (3), 32 (1991).].
21. T. Hanamura, F. Yin, K. Nagai. ISIJ Int. 44, 610 (2004). Crossref

Funding

1. Russian Foundation for Basic Research - 18-08-00340_a