Local stress state of materials with an hcp lattice and plastic zones under the fracture surface

G.V. Klevtsov, R.Z. Valiev, N.A. Klevtsova, I.P. Semenova, I.N. Pigaleva, M.L. Linderov show affiliations and emails
Received 19 May 2019; Accepted 18 July 2019;
This paper is written in Russian
Citation: G.V. Klevtsov, R.Z. Valiev, N.A. Klevtsova, I.P. Semenova, I.N. Pigaleva, M.L. Linderov. Local stress state of materials with an hcp lattice and plastic zones under the fracture surface. Lett. Mater., 2020, 10(1) 16-21
BibTex   https://doi.org/10.22226/2410-3535-2020-1-16-21

Abstract

Relationship of the t/(K1C/σ0.2)2 and hmax/t criteria for materials in the bcc lattice (dark dots), fcc lattice (light dots) and hcp lattice (combined dots) in CG state (1-4, 7-9, 11, 14) and also in the UFG state (5, 6, 10, 12, 13, 15). The vertical line meets the criterion t/(K1C/σ0.2)2 ≥ 2.5. 1 – С20; 2 – С40; 3 – Fe-0.15C-2Cr-1Mo-1V; 4 – 9MnSi5; 5 – С45 (ECAP); 6 - 9MnSi5 (ECAP); 7 – ENAW-2024; 8 – Fe-0.03C-13Cr-0.1N-19Mn; 9 – ENAW-2618A; 10 – ENAW-2618A (ECAP); 11 – Ti-6Al-4V; 12 – Ti-6Al-4V (ECAP); 13 – Ti-6Al-4V (ECAP + IS); 14 – Ti-6Al-4Mo; 15 – Ti-6Al-4Mo (HR)The work is aimed at establishing a relationship between the criteria for estimating the local stress state hmax / t (where hmax is the maximum depth of the plastic zone under the fracture surface, t is the thickness of the sample or part) and the criterion of fracture mechanics t / (K1C / σ0.2)2 for materials with an hcp lattice. The titanium alloys Ti-6Al-4Mo and Ti-6Al-4V were investigated in the initial coarse-grained (CG) and ultrafine-grained (UFG) states. The UFG state was processed by rotary forging (RF) in Ti-6Al-4Mo alloy and by equal-channel angular pressing (ECAP) and ECAP followed by isothermal forging (IF) in Ti-6Al-4V alloy. Testing of alloys for static crack resistance (K1C) was carried out on prismatic specimens with a thickness of 10 mm according to the three-point bending scheme in a liquid nitrogen environment (−196°C). The depth of the plastic deformation zones under the fracture surfaces was determined by the X-ray method. The test results showed that UFG alloys had a lower K1C value than the alloys in the CG state. According to the criterion t / (K1C / σ0.2)2 > 2.5, the fracture of all samples occurred under plane strain (PS) condition. According to the criterion hmax / t <10−2, only samples with the UFG structure were fractured under PS conditions. Analysis of the graphical dependence, reflecting the relationship of the criteria t / (K1C / σ0.2)2 and hmax / t for titanium alloys Ti-6Al-4Mo and Ti-6Al-4V showed that for materials with an hcp lattice, the PS condition can be written as t / (K1С / σ0.2)2 ≥10.

References (20)

1. K. Hellan. Vvedeniye v mekhaniku razrusheniya. Moscow, Mir (1988) 364 p. (in Russian) [K. Хеллан. Введение в механику разрушения. Москва. Мир (1988). 364 с].
2. V. Z. Parton, E. M. Morozov. Mekhanika uprugoplasticheskogo razrusheniya. Moscow, Nauka (1985) 504 p. (in Russian) [В. З. Партон, Е. М. Морозов. Механика упругопластического разрушения. Москва. Наука (1985) 504 с.].
3. A. Hohenwarter, R. Pippan. Acta Materialia. 61, 2973 (2013). Crossref
4. I. Sabirov, R. Z. Valiev, I. P. Semenova, R. Pippan. Metallurgical and materials transactions. 41A, 727 (2010). 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. Prochnost' i mekhanizmy razrusheniya ob"yemnykh nanostrukturirovannykh metallicheskikh materialov. 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. A. J. McEvily. Metal Failures: Mechanisms, Analysis, Prevention. New York, Wiley & Sons (2002) 324 р.
8. G. V. Klevtsov, L. R. Botvina, N. A. Klevtsova, L. V. Limar. Fraktodiagnostika razrusheniya metallicheskikh materialov i konstruktsiy. 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.].
9. L. C. Moroz. Mekhanika i fizika deformatsiy i razrusheniya. Leningrad, Engineering (1984) 224 p. (in Russian) [Л. С. Мороз. Механика и физика деформаций и разрушения. Ленинград, Машиностроение (1984) 224 с.].
10. V. I. Vladimirov. Fizicheskaya priroda razrusheniya materialov. Moscow, Metallurgy (1984) 280 p. (in Russian) [В. И. Владимиров. Физическая природа разрушения материалов. Москва, Металлургия (1984) 280 с.].
11. L. R. Botvina, N. A. Klevtsova, A. P. Fot. Metal Science and Heat Treatment. 52 (7), 396 (2010).
12. G. V. Klevtsov, L. R. Botvina, N. A. Klevtsova. ISIJ International. 36 (2), 222 (1996). Crossref
13. N. A. Klevtsova, O. A. Frolova, G. V. Klevtsov. Razrusheniye austenitnykh staley i martensitnyye prevrashcheniya v plasticheskikh zonakh. Moscow, AE (2005) 155 p. (in Russian) [Н. А. Клевцова, О. А. Фролова, Г. В. Клевцов. Разрушение аустенитных сталей и мартенситные превращения в пластических зонах. Москва, АЕ (2005) 155 с.].
14. G. V. Klevtsov, L. R. Botvina, N. A. Klevtsova. ISIJ International. 36 (2), 215 (1996). Crossref
15. G. V. Klevtsov, N. A. Klevtsova, R. Z. Valiev, I. N. Pigaleva, O. A. Frolova. Bulletin of the Tambov University. Series: Natural and Technical Sciences. 21 (3), 772 (2016) (in Russian) [Г. В. Клевцов, Н. А. Клевцова, Р. З. Валиев, И. Н. Пигалева, О. А. Фролова. Вестник Тамбовского университета. Серия: Естественные и технические науки. 21 (3), 772 (2016).]. Crossref
16. G. Klevtsov, N. Klevtsova, R. Valiev, I. Pigaleva In: The International science and technical congress on Aerospace materials plastic deformation processes. Science, technology, industry (Ed. by A. M. Shterenberg). Samara, SSAU (2017) pp. 81 - 84.
17. ASM Handbook, Metalworking: Bulk Forming (Ed. by S. L. Semiatin). ASM International®. 14A (2005) pp. 179 - 182. Crossref
18. R. Z. Valiev, A. P. Zhilyaev, T. G. Langdon. Bulk Nanostructured Materials: Fundamentals and Applications. TMS, WILEY (2014) 440 p. Crossref
19. Y. Estrin, A. Vinogradov. Extreme grain refinement by severe plastic deformation: A wealth of challenging science. Acta Materialia. 61, 782 (2013).
20. R. Z. Valiev, G. V. Klevtsov, I. P. Semenova, N. A. Klevtsova, D. V. Gunderov, M. V. Fesenuk, M. R. Kashapov. Deformatsiya i Razrushenie materialov. 11, 32 (2012). (in Russian) [Р. З. Валиев, Г. В. Клевцов, И. П. Семенова, Н. А. Клевцова, Д. В. Гундеров, М. В. Фесенюк, М. Р. Кашапов. Деформация и разрушение материалов. 11, 32 (2012).].

Funding

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