Kinetics and the fracture mechanism in low-cycle fatigue range and static crack resistance of the Mg6Al magnesium alloy after annealing and equal channel angular pressing

G.V. Klevtsov, R.Z. Valiev, N.A. Klevtsova, O.B. Kulyasova ORCID logo , E.D. Merson ORCID logo , M.L. Linderov ORCID logo , A.V. Ganeev ORCID logo show affiliations and emails
Received 02 March 2020; Accepted 09 July 2020;
This paper is written in Russian
Citation: G.V. Klevtsov, R.Z. Valiev, N.A. Klevtsova, O.B. Kulyasova, E.D. Merson, M.L. Linderov, A.V. Ganeev. Kinetics and the fracture mechanism in low-cycle fatigue range and static crack resistance of the Mg6Al magnesium alloy after annealing and equal channel angular pressing. Lett. Mater., 2020, 10(4) 398-403
BibTex   https://doi.org/10.22226/2410-3535-2020-4-398-403

Abstract

A straight-line section of the kinetic diagrams of the fatigue fracture of the Mg6Al magnesium alloy after annealing (white dots) and after ECAP (black dots). The test samples were carried out at loads of 800 and 1000 N.We studied the static crack resistance, kinetics and fracture mechanism in the low-cycle fatigue range of the Mg6Al magnesium alloy (5.6 % Al; 0.245 % Mn; 0.047 % Cl; 0.046 % Ca) after homogenization annealing (dav = 85 μm) and after equal-channel angular pressing (ECAP) (dav = 20 μm). Fatigue tests of the rectangular samples with a 10 mm thickness were carried out at a temperature of 20°C according to the three-point bending scheme on an Instron 8802 setup at ν =10 Hz, R = 0.1 and various load values ΔP. The microfractographic features of the fracture surface were studied in the SIGMA scanning electron microscope (SEM) by «ZEISS» and in a confocal laser scanning microscope (CLSM) Lext OLS4000. It has been shown that after annealing the alloy has extremely low hardness and low tensile mechanical properties. After ECAP, hardness, tensile strength, and yield strength increased by 1.2 –1.3 times, and elongation, despite strain hardening, also increased. It was shown that the static crack resistance (КС) of the alloy after ECAP was slightly higher compared to the annealed state. At the same value of ΔK, the propagation rate of a fatigue crack in the ECAPed Mg6Al alloy is lower than in the annealed one, that is favorable in terms of structural strength of the material. The coefficient n in the Paris equation for the annealed alloy is higher than for the ECAPed one. This indicates a lower sensitivity of the alloy after ECAP to cyclic overloads. The microrelief of the fatigue fracture surfaces of the Mg6Al alloy both after ECAP and in the annealed state is characterized by cleavage-like facets with fluted morphology.

References (24)

1. M. A. Shtremel. Fracture. In 2 book. Book 1. The fracture of the material. Moscow: Publishing House MISiS House (2014) 670 p. (in Russian) [М. А. Штремель. Разрушение. В 2 кн. Кн. 1. Разрушение материала. Москва, Изд. Дом МИСиС (2014) 670 с.].
2. A. J. McEvily. Metal Failures: Mechanisms, Analysis, Prevention. Wiley & Sons (2002) 324 р.
3. R. Z. Valiev, A. P. Zhilyaev, T. G. Langdon. Bulk Nanostructured Materials: Fundamentals and Applications. TMS, WILEY (2014) 440 p. Crossref
4. C. S. Chung, J. K. Kim, H. K. Kim, W. J. Kim. Mater. Sci. Eng. A. 337, 39 (2002). Crossref
5. A. Vinogradov, S. Nagasaki, V. Patland, K. Kitagawa, M. Kawazoe. Nanostruct. Mater. 11, 925 (1999). Crossref
6. P. S. Pao, H. N. Jones, S. F. Cheng, C. R. Feng. Int. Jour. Fat. 27, 1164 (2004). Crossref
7. P. Cavaliere. Int. Jour. Fat. 31, 1476 (1999). Crossref
8. L. Collini. Eng. Frac. Mech. 77. 1001 (2010). Crossref
9. H. K. Kim, M. I. Choi, C. S. Chung, D. H. Shin. Mater. Sci. Eng. A. 340, 243 (2003). Crossref
10. T. Hanlon, E. D. Tabachnikova, S. Suresh. Int. Jour. Fat. 27, 1147 (2005). Crossref
11. L. W. Meyer, K. Sommer, T. Halle, M. Hockauf. Jour. Mater. Sci. 43, 7426 (2008). Crossref
12. Y. Estrin, A. Vinogradov. Int. Jour. of Fatigue. 32, 898 (2010). Crossref
13. H. Mughrabi, H. W. Hoppel, M. Kautz. Scripta Materialia. 51, 807 (2004). Crossref
14. L. W. Meyer, K. Sommer, T. Halle, M Hockauf. Materials Science Forum. 584 - 586, 815 (2008). Crossref
15. I. P. Semenova, G. Kh. Salimgareeva, V. V. Latysh, T. Lowe, R. Z. Valiev. Mater. Sci. Eng. A. 503, 92 (2009). Crossref
16. L. R. Saitova, H. W. Hoeppel, M. Goeken, A. R. Kilmametov, I. P. Semenova, R. Z. Valiev. Mater. Sci. Forum. 584 - 586, 827 (2008). Crossref
17. А. Vinogradov. J. Mater. Sci. 42, 1797 (2007). Crossref
18. P. А. Paris, F. A. Erdogan. Trans. ASME, S. D. 4, 582 (1963).
19. J. R. Rice. ASTM. Special Technical Publication. 415, 247 (1966).
20. 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.].
21. D. A. Meyn, E. J. Brooks. Microstructural Origin of Flutes and Their Use in Distinguishing Striationless Fatigue Cleavage from Stress-Corrosion Cracking in Titanium Alloys. In: Fractography Mater. Sci. ASTMSTP 733. (Ed. by L. N. Gilbertson, R. D. Zipp). American Society for Testing and Materials (1981) pp. 5 - 31.
22. S. P. Lynch, P. Trevena. Corrosion. 44, 113 (1988). Crossref
23. T. Motooka, K. Kiuchi. Corrosion. 58, 535 (2002). Crossref
24. E. Merson, V. Poluyanov, P. Myagkikh, D. Merson, A. Vinogradov. Mater. Sci. Eng. A. 772, 138744 (2020). Crossref

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Funding

1. This work was supported by the Russian Fond Fundamental Investigation (RFFI) - grant number 18-08-00340_a