Investigation of Homogenization Process of the 5019 Alloy Extrusion Billets

Abstract:

In the paper, the influence of homogenization parameters on the microstructure and properties of the 5019 alloy DC-cast billets was analysed. At the first stage, the microstructure of the alloy in as-cast state was investigated using SEM/EDS technique. Additionally, a DSC test and hardness measurements were performed. In the as-cast material, the presence of the dendritic microstructure with a pronounced microsegregation of magnesium in the dendrites cross-section was found. Subsequently, the specimens were subjected to laboratory homogenization experiments, with different soaking conditions and water quenching. The microstructural effects of the investigated variants of homogenization were evaluated using the same techniques as in the case of the as-cast alloy. It was found that after homogenization, with soaking at the temperature of 530 °C for 6 hours, the microsegregation is eliminated and the concentration of magnesium in the grains centres is over two times greater than in the dendrites cores before annealing. The solidus temperature rises by about 12 °C in comparison to the as-cast state. Neither extending the soaking time nor rising the temperature contributes to a further increase of the solidus temperature, or the magnesium concentration in the grains interiors. However, the tendency of dispersoids to grow and the change of Fe-bearing constituents chemical composition were observed after the high temperature, or prolonged annealing variants.

• Periodical: Key Engineering Materials (Volume 682)
• Pages: 10-17
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.682.10
• Online since: February 2016
• Authors: Antoni Woźnicki*, Dariusz Lesniak, Grzegorz Włoch, Alicja Wojtyna, Monika Zabrzańska
• Keywords: 5019 Alloy, Billets Homogenization, DSC, SEM

References

[1] Predel B, Phase Equilibria Crystallographic and Thermodynamic Data of Binary Alloys, Springer, Berlin, (1998).

[2] A. Łatkowski, J. Jarominek, Metaloznawstwo metali nieżelaznych, Wydawnictwa AGH, Kraków, (1994).

[3] L. Backerund, E. Krol, J. Tamminen, Solidification Characteristics of Aluminium Alloys Vol. 1, SkanAluminium, Oslo, (1986).

[4] S. Thompson, S. L. Cockcroft, M. A. Wells, Effect of cooling rate on solidification characteristics of aluminium alloy AA 5182, Materials Science and Technology 20 (2004) 497-504.

DOI: 10.1179/026708304225012053

[5] T. Sheppard, Extrusion of Aluminium Alloys, Kluwer Academic Publishers, Dordrecht, (1999).

[6] SL Lee, ST Wu, Influence of soaking treatments on hot ductility of Al-4. 85 pct Mg alloys containing Mn, Metallurgical Transactions A 17A (1986) 833-841.

DOI: 10.1007/bf02643859

[7] T. Sheppard, N. Raghunathan, Modification of cast structures in Al–Mg alloys by thermal treatments, Materials Science and Technology 5 (1989) 268-280.

DOI: 10.1179/mst.1989.5.3.268

[8] SL Lee, ST Wu, Identification of dispersoids in Al-Mg alloys containing Mn, Metallurgical Transactions A 18A (1987) 1353-1357.

DOI: 10.1007/bf02646649

[9] T. Radetić, M. Popović, E. Romhanji, Microstructure evolution of a modified AA5083 aluminum alloy during a multistage homogenization treatment, Materials Characterization 65 (2012) 16–27.

DOI: 10.1016/j.matchar.2011.12.006

[10] Y. J. Li, L. Arnberg, A eutectoid phase transformation for the primary intermetallic particle from Alm(Fe, Mn) to Al3(Fe, Mn) in AA5182 alloy, Acta Materialia 52 (2004) 2945–2952.

DOI: 10.1016/j.actamat.2004.02.041

[11] N. A. Belov, D. G. Eskin, A. A. Aksenov, Multicomponent Phase Diagrams: Applications for Commercial Aluminum Alloys, Elsevier, Amsterdam [etc. ], (2005).

[12] M. Bauser, G. Sauer, K. Siegert, Extrusion, Second Edition, ASM International, Materials Park, (2006).

[13] R. Shahani, R. Tirard-Collet, C. Sigli, Optimized 6xxx alloy Billet Performance: A Structured Approach, Proc. of 7th Int. Aluminum Extrusion Technology Seminar, Chicago 2000, vol. 2, p.13 – 22.

[14] T. Minoda, S. Hayakawa, S. Matsuda, Y. Sumitomo, The Mechanism of Pick-up Formation on 6063 Aluminum Extrusions, Proc. of 7th Int. Aluminum Extrusion Technology Seminar, Chicago 2000, vol. 2, p.23 – 29.

[15] S. R. Claves, D. L. Elias, W. Z. Misiołek, Analysis of the lntermetallic Phase Transformation Occurring During Homogenization of 6xxx Aluminum Alloys, Materials Science Forum 396-402 (2002) 667-674.

DOI: 10.4028/www.scientific.net/msf.396-402.667

[16] S. Martinez De La Puente, B. Verlinden, L. Delaey, Hot workability of an Al-Mg alloy AA5182 with 1 wt% Cu, Journal of Materials Science 29 (1994) 6167-6174.

DOI: 10.1007/bf00354557