Low Temperature Superplasticity in Ultrafine-Grained AZ31 Alloy

Abstract:

The mechanical behavior of an AZ31 magnesium alloy processed by high-pressure torsion (HPT) was evaluated by tensile testing from room temperature up to 473 K at strain rates between 10^-5 – 10^-2 s^-1. Samples tested at room temperature and at high strain rates at 373 K failed without any plastic deformation. However, significant ductility, with elongations larger than 200%, was observed at 423 K and 473 K and at low strain rates at 373 K. The high elongations are attributed to a pronounced strain hardening and a high strain rate sensitivity. The results agree with reports for a similar alloy processed by severe plastic deformation. However, the level of flow stress is lower and the strain rate sensitivity and the elongations are larger than observed in this alloy processed by conventional thermo-mechanical processing.

• Periodical: Defect and Diffusion Forum (Volume 385)
• Pages: 59-64
• DOI: https://doi.org/10.4028/www.scientific.net/DDF.385.59
• Online since: July 2018
• Authors: Roberto B. Figueiredo*, Pedro Henrique R. Pereira, Terence G. Langdon
• Keywords: Ductility, High-Pressure Torsion, Magnesium Alloy, Superplasticity

References

[1] M. Kawasaki, R.B. Figueiredo, T.G. Langdon, The Requirements for Superplasticity with an Emphasis on Magnesium Alloys, Advanced Engineering Materials 18(1) (2016) 127-131.

DOI: 10.1002/adem.201500068

[2] K. Matsubara, Y. Miyahara, Z. Horita, T.G. Langdon, Developing superplasticity in a magnesium alloy through a combination of extrusion and ECAP, Acta Materialia 51(11) (2003) 3073-3084.

DOI: 10.1016/s1359-6454(03)00118-6

[3] M. Kai, Z. Horita, T.G. Langdon, Developing grain refinement and superplasticity in a magnesium alloy processed by high-pressure torsion, Materials Science and Engineering A 488(1-2) (2008) 117-124.

DOI: 10.1016/j.msea.2007.12.046

[4] R.B. Figueiredo, M. Kawasaki, T.G. Langdon, Developing superplasticity in metallic alloys through the application of severe plastic deformation, Materials Science Forum, 2009, pp.97-111.

DOI: 10.4028/www.scientific.net/msf.604-605.97

[5] R.B. Figueiredo, T.G. Langdon, Developing superplasticity in a magnesium AZ31 alloy by ECAP, Journal of Materials Science 43(23-24) (2008) 7366-7371.

DOI: 10.1007/s10853-008-2846-0

[6] R.B. Figueiredo, T.G. Langdon, Record Superplastic Ductility in a Magnesium Alloy Processed by Equal-Channel Angular Pressing, Advanced Engineering Materials 10 (2008) 37-40.

DOI: 10.1002/adem.200700315

[7] R.B. Figueiredo, T.G. Langdon, The development of superplastic ductilities and microstructural homogeneity in a magnesium ZK60 alloy processed by ECAP, Materials Science and Engineering A 430(1-2) (2006) 151-156.

DOI: 10.1016/j.msea.2006.05.056

[8] R.Z. Valiev, T.G. Langdon, Principles of equal-channel angular pressing as a processing toold for grain refinement, Progress in Materials Science 51 (2006) 881-981.

DOI: 10.1016/j.pmatsci.2006.02.003

[9] A.P. Zhilyaev, T.G. Langdon, Using high-pressure torsion for metal processing: Fundamentals and applications Progress in Materials Science 53(6) (2008) 893-979.

DOI: 10.1016/j.pmatsci.2008.03.002

[10] R.B. Figueiredo, T.G. Langdon, Strategies for achieving high strain rate superplasticity in magnesium alloys processed by equal-channel angular pressing, Scripta Materialia 61(1) (2009) 84-87.

DOI: 10.1016/j.scriptamat.2009.03.012

[11] R.B. Figueiredo, S. Sabbaghianrad, A. Giwa, J.R. Greer, T.G. Langdon, Evidence for exceptional low temperature ductility in polycrystalline magnesium processed by severe plastic deformation, Acta Materialia 122 (2017) 322-331.

DOI: 10.1016/j.actamat.2016.09.054

[12] R.B. Figueiredo, F.S.J. Poggiali, C.L.P. Silva, P.R. Cetlin, T.G. Langdon, The influence of grain size and strain rate on the mechanical behavior of pure magnesium, Journal of Materials Science 51(6) (2016) 3013-3024.

DOI: 10.1007/s10853-015-9612-x

[13] H. Somekawa, T. Mukai, Hall–Petch Breakdown in Fine-Grained Pure Magnesium at Low Strain Rates, Metallurgical and Materials Transactions A 46(2) (2015) 894-902.

DOI: 10.1007/s11661-014-2641-2

[14] J. Straska, M. Janecek, J. Gubicza, T. Krajnak, E.Y. Yoon, H.S. Kim, Evolution of microstructure and hardness in AZ31 alloy processed by high pressure torsion, Materials Science and Engineering A 625 (2015) 98-106.

DOI: 10.1016/j.msea.2014.12.005

[15] J. Xu, X.W. Wang, M. Shirooyeh, G.N. Xing, D.B. Shan, B. Guo, T.G. Langdon, Microhardness, microstructure and tensile behavior of an AZ31 magnesium alloy processed by high-pressure torsion, Journal of Materials Science 50(22) (2015) 7424-7436.

DOI: 10.1007/s10853-015-9300-x

[16] L.R.C. Malheiros, R.B. Figueiredo, T.G. Langdon, Grain size and microhardness evolution during annealing of a magnesium alloy processed by high-pressure torsion, Journal of Materials Research and Technology 4(1) (2015) 14-17.

DOI: 10.1016/j.jmrt.2014.10.008

[17] R.B. Figueiredo, T.G. Langdon, Grain refinement and mechanical behavior of a magnesium alloy processed by ECAP, Journal of Materials Science 45(17) (2010) 4827-4836.

DOI: 10.1007/s10853-010-4589-y

[18] K.S. Fong, A. Danno, M.J. Tan, B.W. Chua, Tensile flow behavior of AZ31 magnesium alloy processed by severe plastic deformation and post-annealing at moderately high temperatures, Journal of Materials Processing Technology 246(Supplement C) (2017).

DOI: 10.1016/j.jmatprotec.2017.03.025

[19] H.K. Lin, J.C. Huang, T.G. Langdon, Relationship between texture and low temperature superplasticity in an extruded AZ31 Mg alloy processed by ECAP, Materials Science and Engineering: A 402(1) (2005) 250-257.

DOI: 10.1016/j.msea.2005.04.018

[20] Y.Q. Cheng, H. Zhang, Z.H. Chen, K.F. Xian, Flow stress equation of AZ31 magnesium alloy sheet during warm tensile deformation, Journal of Materials Processing Technology 208(1) (2008) 29-34.

DOI: 10.1016/j.jmatprotec.2007.12.095