Segregation Characteristics of Rheo-High Pressure Die Cast Al-Alloy 2139 Plates

Abstract:

Al-Cu-Mg-Ag alloy 2139 is a wrought alloy that is heat-treatable and used in aerospace constructions. This is mainly due to the addition of silver in the alloy. Hot-tearing is a problem for casting wrought alloys with conventional liquid casting techniques. The risk is reduced by using rheo-high pressure die casting (R-HPDC) to allow the alloy to be used for near-net shape forming of components. This study investigates the segregation characteristics of R-HPDC alloy 2139. The effects of segregation on the age-hardening response as well as the tensile properties are studied. The chemical composition differences across the casting were found to aid in correlation of results. It is found that segregation occurs in three dimensions, namely from the surface to the centre of the casting, as well as across the width and length of the casting.

• Periodical: Materials Science Forum (Volumes 828-829)
• Pages: 100-105
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.828-829.100
• Online since: August 2015
• Authors: Carlien Taute*, Heinrich Möller
• Keywords: Age-Hardening, Alloy 2139, Rheo-High Pressure Die Casting (R-HPDC), Segregation, Yield Strength

References

[1] A. Cho; B. Bes, Damage Tolerance Capability of an Al-Cu-Mg-Ag Alloy (2139). Materials Science Forum. 519-521 (2006) 603-608.

DOI: 10.4028/www.scientific.net/msf.519-521.603

[2] W.M. Lee; M.A. Zikry, Microstructural characterisation of a high-strength aluminium alloy subjected to high strain-rate impact. The Minerals, Metals & Materials Society and ASM International 42A (2010) 1215-1221.

DOI: 10.1007/s11661-010-0476-z

[3] M. Vural; J. Caro, Experimental analysis and constitutive modeling for the newly developed 2139-T8 alloy. Materials Science and Engineering 520 (2009) 56-65.

DOI: 10.1016/j.msea.2009.05.026

[4] Information on http: /www. pa-international. com. au [Accessed: January 2015].

[5] D. Bakavos; P.B. Prangnell; B. Bes; F. Eberl, The effect of silver on microstructural evolution in two 2xxx series Al-alloys with a high Cu: Mg ratio during ageing to a T8 temper. Materials Science and Engineering 491(1) (2008) 214-223.

DOI: 10.1016/j.msea.2008.03.014

[6] U.A. Curle; H. Möller; G. Govender, R-HPDC in South Africa. Solid State Phenomena 192-193 (2013) 3-15.

DOI: 10.4028/www.scientific.net/ssp.192-193.3

[7] H. Möller; G. Govender, The heat treatment of rheo-high pressure die cast Al-Cu-Mg-Ag alloy 2139. Solid State Phenomena 192-193 (2013) 173-178.

DOI: 10.4028/www.scientific.net/ssp.192-193.173

[8] P. Daswa; H. Moller; G. Govender, Optimization of the solution heat treatment of rheo-high pressure die cast Al-Cu-Mg-Ag 2139 aluminium alloy. Submitted to 7th Light Metals Technology Conference 2015 (LMT2015), Port Elizabeth, South Africa, 27-29 July (2015).

DOI: 10.4028/www.scientific.net/msf.828-829.226

[9] H. Möller; U.A. Curle; E.P. Masuku, Characterisation of surface liquid segregation in SSM-HPDC aluminium alloys 7075, 2024, 6082 and A201. Transaction of Nonferrous Metals Society of China 20 (2010) s847-s851.

DOI: 10.1016/s1003-6326(10)60593-6

[10] L. Chauke; P. Daswa; H. Moller; G. Govender, The effect of natural pre-ageing time on the mechanical properties of rheo-high pressure die cast 2139 wrought alloy after optimised T6 temper condition. Submitted to 7th Light Metals Technology Conference 2015 (LMT2015), Port Elizabeth, South Africa, 27-29 July (2015).

DOI: 10.4028/www.scientific.net/msf.828-829.244

[11] T.F. Morgeneyer; M.J. Starink; I. Sinclair, Evolution of voids during ductile crack propagation in an Al alloy sheet toughness test studied by synchrotron radiation computed tomography. Acta Materialia 56 (2008) 1671-1679.

DOI: 10.1016/j.actamat.2007.12.019