Comparison of microstructures and mechanical properties of Al 7075 alloy obtained from conventional modified SIMA processes

Subject Areas : journal of New Materials

M. Karamouz ¹ , M. Alizadeh ² , A.R. Ahmadi ³

1 - Department of Metals, Institute of Science and High Technology and Environmental Sciences, Graduate University of Advanced Technology, Kerman, Iran
2 - Department of Metals, Institute of Science and High Technology and Environmental Sciences, Graduate University of Advanced Technology, Kerman, Iran
3 - Department of Mechanical Engineering, Graduate University of Advanced Technology, Kerman, Iran

Received: 2017-07-21 Accepted : 2018-01-06 Published : 2018-07-23

Keywords: mechanical properties, SIMA, Semi-solid forming, Al 7075 alloy,

Abstract :

     In this study, the microstructures and mechanical properties of Al 7075 alloy obtained from conventional and modified SIMA have been investigated. In fact, the appropriate microstructure for the semi-solid forming is the non-dendritic microstructure with enough degree of spheroidity. In this research, a type of modified SIMA was used to make a comparison with the conventional SIMA. An annealed strip of Al 7075 alloy after rolling was soaked in an electrical furnace at 590 °C for different periods and then was cooled to 500 °C and quenched in cold water. After that, the mentioned procedure was repeated without rolling. The results showed noticeable improvement in the microstructure and the mechanical properties of the alloy processed by the modified SIMA. Not only was the globular structure finer and more homogenous but also, a more homogenous distribution of the secondary phase particles in a non-continuous manner was obtained at the grain boundaries and the eutectic structure was removed. These led to the improved mechanical properties such as ultimate tensile strength from 371 MPa to 442 MPa, elongation from 4.2 % to 13.1 %. In addition, although the maximum microhardness at grain boundaries decreased, the microhardness level within the grains improved and formability enhanced severely.

References:

References:
1- Y. Sirong, L. Dongcheng, N. Kim, " Microstructure evolution of SIMA processed Al2024'', Materials Science and Engineering: A, Vol. 420, pp. 165-170, 2006.

 

2- G. Yan, S. Zhao, S. Ma, H. Shou, " Microstructural evolution of A356.2 alloy prepared by the SIMA process'', Materials Characterization, Vol. 69, pp. 45-51, 2012.

 

3- C. W. Lin, F. Y. Hung, T. S. Lui, L. H. Chen, “High-temperature deformation resistance and forming behavior of two-step SIMA-processed 6066 alloy”, Materials Science and Engineering: A, Vol. 659, pp. 143-157, 2016.

 

4- E.Parshizfarda, S.G.Shabestari, “An investigation on the microstructural evolution and mechanical properties of A380 aluminum alloy during SIMA process”, Journal of Alloys and Compounds, Vol. 509, pp. 9654-9658, 2011.

 

5- C. W. Lin, F. Y. Hung, T. S. Lui, L. H. Chen, “Microstructure evolution and high-Temperature compressibility of modified two-Step strain-induced melt activation-processed Al-Mg-Si aluminum alloy”, Metals, Vol. 6, pp. 113-125, 2016.

 

6- J.G. Wang, P. Lu, H.Y. Wang, J.F. Liu, Q.C. Jiang, “Semisolid
microstructure evolution of the predeformed AZ91D alloy during heat treatment”, Journal of Alloys and Compounds, Vol. 395, pp. 108-112, 2005.

 

7- O. Lashkari, R. Ghomashchi, “The implication of rheology in semi-solid metal processes: An overview”,  Journal of Materials Processing Technology, Vol. 182, pp. 229-240, 2007

 

8- A. Bolouri, M. Shahmiri, E.N.H. Cheshmeh,  “Microstructural evolution during semisolid state strain induced melt activation process of aluminum 7075 alloy'', Transactions of Nonferrous Metals Society of China,  Vol. 20, pp. 1663-1671, 2010.

 

9- N. Haghdadi, A. Zarei-Hanzaki, S. Heshmati-Manesh, H. Abedi, S. Hassas-Irani, “The semisolid microstructural evolution of a severely deformed A356 aluminum alloy”, Materials & Design, Vol. 49, pp. 878-887, 2013.

 

10- C. Mondal, A. Mukhopadhyay, “On the nature of T(Al2Mg3Zn3) and S(Al2CuMg) phases present in as-cast and annealed 7055 aluminum alloy”, Materials Science and Engineering: A, Vol. 391, pp. 367-376, 2005.

 

11- A. Bolouri, M. Shahmiri, C.G. Kang, “Coarsening of equiaxed microstructure in the semisolid state of aluminum 7075 alloy through SIMA processing”, Journal of Materials Science, Vol. 47, pp. 3544–3553, 2012.

 

12- A. Haghparast, M. Nourimotlagh, M. Alipour, " Effect of the strain-induced melt activation (SIMA) process on the tensile properties of a new developed super high strength aluminum alloy modified by Al5Ti1B grain refiner '', Materials Characterization, Vol. 71, pp. 6-18, 2012.

 

13- M. Alipour, M. Emamy, S.H.S. Ebrahimi, M. Azarbarmas, M. Karamouz, J. Rassizadehghani, " Effects of pre-deformation and heat treatment conditions in the SIMA process on properties of an Al–Zn–Mg–Cu alloy modified by Al–8B grain refiner'', Materials Science and Engineering: A,  Vol. 528, pp. 4482-4490, 2011.

 

14- M.R. Rokni, A. Zarei-Hanzaki, H.R. Abedi, N. Haghdadi, " Microstructure evolution and mechanical properties of backward thixoextruded 7075 aluminum alloy '', Materials & Design,  Vol. 36, pp. 557-563, 2012.

 

15- S. Chayong, H. Atkinson, P. Kapranos, " Multistep induction heating regimes for thixoforming 7075 aluminium alloy'', Materials science and technology, Vol. 20, pp. 490-496, 2004.