Microstructure, Texture, and Mechanical Properties of Continuously Extruded and Rolled AZ31 Magnesium Alloy Sheets
- 62 Downloads
It is difficult to fabricate magnesium alloy sheets at room temperature due to their hexagonal close-packed structure. In this paper, we proposed a new process that can be used to fabricate AZ31 magnesium alloy sheets with fine-grained microstructure and good mechanical properties. AZ31 magnesium alloy sheets with dimensions of 160 mm × 8 mm were obtained successfully by a continuous extrusion technique. The extruded sheets were then rolled by two different rolling routes, Route 1: the extruded sheet was heated at 350 °C and then rolled without heating of rolls and Route 2: the sheet was rolled without any previous heating by heating rolls at 280 °C. The microstructure and texture evolution as well as mechanical properties of the continuously extruded and rolled sheets were examined experimentally. The magnesium alloy sheets with relatively fine grains of 4.5-8.3 µm were obtained by continuous extrusion followed by rolling processes. The tensile strength of continuously extruded AZ31 Mg alloy sheets can be effectively increased by rolling using heating rolls (Route 2), while the ductility was enhanced by rolling heated sheets (Route 1). The mixed microstructure, consisting of refined DRX grains and deformed grains, contributes to enhancement in tensile strength of the sheet samples rolled by Route 2 due to grain-boundary strengthening and work hardening. Lower temperature and larger rolling reduction are two main factors for improving the tensile strength of AZ31magnesium alloy sheets.
Keywordscontinuous extrusion magnesium alloys microstructure rolling tensile properties
This work was supported partly by the National Natural Science Foundation of China (Grant Number: 51401043) and Liaoning Provincial Nature Science Foundation of China (Grant Number: 2019-MS-035). The authors would like to acknowledge the help from the members of BAOSTEEL, China.
- 11.W.Z. Chen, L.M. Ma, X.M. Chen, G.R. Cui, W.C. Zhang, and E.D. Wang, Microstructure Evolution and Mechanical Performance Improvement of Thin ZK61 Magnesium Alloy Sheets Subjected to Cumulative Cold Rolling and Intermediate Annealing, Mater. Sci. Eng. A, 2018, 733, p 350. https://doi.org/10.1016/j.msea.2018.07.067 CrossRefGoogle Scholar
- 12.R. Poss, Sheet Metal Production of Magnesium Alloys, Mater. Sci. Forum, 2003, 419–422, p 327–336. https://doi.org/10.4028/www.scientific.net/MSF.419-422.327 CrossRefGoogle Scholar
- 13.L.X. Zhang, W.Z. Chen, W.C. Zhang, W.K. Wang, and E. Wang, Microstructure and Mechanical Properties of Thin ZK61 Magnesium Alloy Sheets by Extrusion and Multi–pass Rolling with Lowered Temperature, J. Mater. Proc. Technol., 2016, 237, p 65–74. https://doi.org/10.1016/j.jmatprotec.2016.06.005 CrossRefGoogle Scholar
- 18.Y.L. He, F. Gao, B.Y. Song, R. Fu, G.M. Wu, J. Li, and L. Jiang, Grain Refinement of Magnesium Alloys by CONFORM: A Continuous Severe Plastic Deformation Route?, Mater. Sci. Forum, 2012, 706–709, p 1781–1786. https://doi.org/10.4028/www.scientific.net/MSF.706-709.1781 CrossRefGoogle Scholar
- 19.G.M. Wu, R. Fu, and F. Gao, Simulation on Continuous Extrusion Forming Process of AZ31 Magnesium Alloy, Hot Working Technol., 2009, 38, p 39–45. https://doi.org/10.14158/j.cnki.1001-3814.2009.17.011 CrossRefGoogle Scholar
- 20.J.Y. Yang, B.Y. Song, H.S. Ning, and R. Fu, Microstructure of AZ31 Magnesium Alloy Produced by the CONFORM Process Under Different Extrusion Wheel Velocities, Adv. Mater. Res., 2011, 189–193, p 2609–2612. https://doi.org/10.4028/www.scientific.net/AMR.189-193.2609 CrossRefGoogle Scholar
- 24.M. Sanjari, A.S.H. Kabir, A. Farzadfar, H. Utsunomiya, R. Petrov, L. Kestens, and S. Yue, Promotion of Texture Weakening in Magnesium by Alloying and Thermomechanical Processing. II: Rolling Speed, J. Mater. Sci., 2014, 49(3), p 1426–1436. https://doi.org/10.1007/s10853-013-7827-2 CrossRefGoogle Scholar
- 34.S.S. Park, G.T. Bae, J.G. Lee, D.H. Kang, K.S. Shin, and N.J. Kim, Microstructure and Mechanical Properties of Twin-Roll Strip Cast Mg Alloys, Mater. Sci. Forum, 2007, 539–543, p 119–126. https://doi.org/10.4028/www.scientific.net/MSF.539-543.119 CrossRefGoogle Scholar