Effect of Cu Content on the Formability and Portevin-Le Chatelier Effect of Al-Mg Alloys

Abstract:

Al-Mg alloys developed for auto body sheets with different Cu contents were fabricated in the laboratory scale. The effects of Cu content on the microstructures, formability and Portevin–Le Chatelier(PLC) effect of the alloys were investigated by polarizied optical microscopy and room temperature tensile testing. It has been found that with increasing Cu content, there was little change of the strain hardening exponent, but the plastic strain ratio and limiting drawing ratio increased firstly and then decreased. A quantitative statistical analysis of the characteristics of the PLC effect was made, including the stress drop and the reloading time, which follow a common linear relationship with plastic strain, and the increase rate of stress drop and reloading time was bigger with more Cu content. A detailed discussion of the corresponding mechanism of Cu and Cu-containing precipitates on the dynamic strain aging(DSA) was made.

• Periodical: Materials Science Forum (Volume 817)
• Pages: 150-157
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.817.150
• Online since: April 2015
• Authors: Peng Cheng Ma, Di Zhang*, Lin Zhong Zhuang, Ji Shan Zhang
• Keywords: Al-Mg Alloys, Cu Content, Formability, Portevin–Le Chatelier(PLC) Effect

References

[1] G.B. Burger, A.K. Gupta, P.W. Jeffrey, D.J. Lloyd, Microstructural control of aluminum sheet used in automotive applications, Materials Characterization, 35(1995) 23-39.

DOI: 10.1016/1044-5803(95)00065-8

[2] G.S. Cole, A.M. Sherman, Lightweight materials for automotive applications, Materials Characterization. 35(1995) 3-9.

[3] W. Wen, Y.M. Zhao, J.G. Morris, The effect of Mg precipitation on the mechanical properties of 5xxx aluminum alloys. Materials Science and Engineering A. 392(2005) 136-144.

DOI: 10.1016/j.msea.2004.09.059

[4] N.S. Lee, J.H. Chen, Anisotropic tensile ductility of cold-rolled and annealed aluminum alloy sheet and the beneficial effect of post-anneal rolling, Scripta Materialia. 60(2009) 340-343.

DOI: 10.1016/j.scriptamat.2008.10.036

[5] H. Takuda, N. Yamazaki, N. Hatta, S. Kikuchi, Influence of cold-rolling and annealing conditions on formability of aluminium alloy sheet, Journal of Materials Sciences. 311(1995) 957-963.

DOI: 10.1007/bf01178430

[6] D. Ravi Kumar, K. Swaminathan, Formability of two aluminium alloys, Materials Science and Technology. 15(1999) 1241-1252.

DOI: 10.1179/026708399101505347

[7] P. Ratchev, B. Verlinden, P. De Smet, Precipitation hardening of an Al–4. 2 wt% Mg–0. 6 wt% Cu alloy, Acta Materialia. 46(1998) 3523-3533.

DOI: 10.1016/s1359-6454(98)00033-0

[8] E. Romhanji, M. Popovic, D. Glisic, Effect of annealing temperature on the formability of Al–Mg4. 5–Cu0. 5 alloy sheets, Journal of Materials Processing Technology, 177(2006) 386-389.

DOI: 10.1016/j.jmatprotec.2006.04.036

[9] Y. Suzuki, M. Matsuo, M. Saga, Properties of bake hardenable Al–Mg–Cu alloy sheets, Materials Science Forum. 217-222(1996) 1789-1794.

DOI: 10.4028/www.scientific.net/msf.217-222.1789

[10] Z.P. Xing, S.B. Kang, H.W. Kim, Softening behavior of 8011 alloy produced by accumulative roll bonding process, Scripta Materiali. 45(2001) 597-604.

DOI: 10.1016/s1359-6462(01)01069-7

[11] S.H. Choi, J.K. Choi, H. W Kim, S.B. Kang, Effect of reduction ratio on annealing texture and r-value directionality for a cold-rolled Al–5% Mg alloy, Materials Science and Engineering A. 519(2009) 77-87.

DOI: 10.1016/j.msea.2009.05.063

[12] H.W. Kim, C.Y. Lim, Annealing of flexible-rolled Al–5. 5 wt%Mg alloy sheets for auto body application, Materials and Design. 31(2010) 571-575.

DOI: 10.1016/j.matdes.2009.12.018

[13] H.Y. Wu, G.Z. Zhou, Mechanical properties and formability of an Mg-6%Li-1%Zn alloy thin sheet at elevated temperatures, Journal of Materials Processing Technology. 206 (2008) 419-424.

DOI: 10.1016/j.jmatprotec.2007.12.045

[14] E. Romhanji, M. Popovic, D. Glisic, V. Milenkovic, Formability of a high-strength Al-Mg6. 8 type alloy sheet, Journal of Materials Science, 33(1998) 1037-1042.

DOI: 10.1023/a:1004328315442

[15] R. Narayanasamy, R. Ravindran, K. Manonmani,J. Satheesh, A crystallographic texture perspective formability investigation of aluminum 5052 alloy sheets at various annealing temperatures, Materials and Design. 30(2009) 1804-1817.

DOI: 10.1016/j.matdes.2008.09.011

[16] W. Wen, J. G Morris, An investigation of serrated yielding in 5000 series aluminum alloys, Materials Science and Engineering A. 354(2003) 279-285.

DOI: 10.1016/s0921-5093(03)00017-0

[17] H. Ait-Amokhtar, C. Fressengeas, Crossover from continuous to discontinuous propagation in the Portevin–Le Chatelier effect, Acta Materialia. 58(2010) 1342-1349.

DOI: 10.1016/j.actamat.2009.10.038

[18] H. Jiang, Q. Zhang,X. Wu, Spatiotemporal aspects of the Portevin–Le Chatelier effect in annealed and solution-treated aluminum alloys, Scripta Materialia. 54(2006) 2041-(2045).

DOI: 10.1016/j.scriptamat.2006.03.027

[19] J. Kang, R.K. Mishra, D.S. Wilkinson, Effect of Mg content on Portevin–Le Chatelier band strain in Al–Mg sheet alloys, Philosophical Magazine Letters, 92(2012) 647-655.

DOI: 10.1080/09500839.2012.714082

[20] R. Narayanasamy, C. Sathiyanarayanan, Forming limit diagram for interstitial free steels: part I, Materials Science and Engineering A. 399(2005) 292–307.

DOI: 10.1016/j.msea.2005.04.004

[21] GB/ T5028- 2008, Metallic materials-Sheet and strip-Determination of tensile strain hardening exponent.

DOI: 10.3403/30113992u

[22] GB/ T5027- 2007, Metallic materials-Sheet and strip-Determination of plastic strain ratio.

[23] D.K. Leu, Prediction of the limiting drawing ratio and the maximum drawing load in cup-drawing, International Journal of Machine Tools and Manufacture. 37(1997) 201-213.

DOI: 10.1016/0890-6955(95)00107-7

[24] Z. Zhu, M.J. Starink, Age hardening and softening in cold-rolled Al–Mg–Mn alloys with up to 0. 4wt%Cu, Materials Science and Engineering A. 489(2008) 138-149.

DOI: 10.1016/j.msea.2007.12.019

[25] G.G. Moore, J.F. Wallace, The effect of anisotropy on instability in sheet metal forming, Journal of the Institute of Metals, 93(1964-1965) 33.

[26] M.G. El-Sebaie, P.B. Mellor, Plastic instability conditions in the deep-drawing of a circular blank of sheet metal, International Journal of Mechanical Science. 14(1972) 535-540.

DOI: 10.1016/0020-7403(72)90055-0

[27] F. Chmelı́k, E. Pink, J. Król, Mechanisms of serrated flow in aluminium alloys with precipitates investigated by acoustic emission, Acta materialia. 46(1998) 4435-4442.

DOI: 10.1016/s1359-6454(98)00070-6

[28] J.M. Robinson, M.P. Shaw, Microstructural and mechanical influences on dynamic strain aging phenomena, International Materials Reviews. 39(1994) 113-122.

DOI: 10.1179/imr.1994.39.3.113