TY - JOUR
T1 - Influence of heat treatment on the microstructure, texture and formability of 2024 aluminium alloy
AU - Moy, Charles K.S.
AU - Weiss, Matthias
AU - Xia, Junhai
AU - Sha, Gang
AU - Ringer, Simon P.
AU - Ranzi, Gianluca
N1 - Funding Information:
The authors gratefully acknowledge the Australian Research Council (ARC) for supporting this work through the ARC Centre of Excellence for Design in Light Metals. They are also thankful for the scientific and technical input and support from the Australian Microscopy & Microanalysis Research Facility (AMMRF) node at the University of Sydney and would like to particularly thank Dr. Patrick Trimby for EBSD imaging. Finally, they are appreciative of the constructive discussion with Dr. Alan Leacock from the University of Ulster.
PY - 2012/8/30
Y1 - 2012/8/30
N2 - We have investigated the effect of heat treatment on the microstructure, texture and formability of high-strength aluminium Al2024 sheets of gauge thicknesses 1.27. mm and 2.03. mm. Both optical and electron microscopy were employed to characterise the microstructure. Tensile tests performed at 0°, 45° and 90° to the rolling direction were used as an indication of the anisotropic behaviour of the sheets. The formability of the sheets was assessed by performing stretch forming tests over a hemispherical punch. Comparison of microstructure and material properties indicated an effect of precipitation hardening on the overall anisotropy of the investigated materials. We report an improvement in the total elongation under uniaxial tension with a loss in strength for 2.5. h and 2 days ageing while the ageing treatment for 1 week (peak hardness) resulted in increased strength with a decline in total elongation. The 1.27. mm thick sheet showed better drawability and least tendency to earing than the thicker sheet. The drawability was the highest at 45° to the rolling direction for the as-received material and those that had been aged for 2.5. h and 2 days. Forming limit diagrams derived from the stretch forming tests showed that the 2 days aged sample had the highest plane strain limit making it the most appropriate condition considering that the plane strain is usually the most critical forming strain in stamping applications. In addition, the 2 days aged sample had its plane strain shifted towards the biaxial stretching area which is likely to have a positive effect on some sheet forming applications. Finally, a formability index was calculated and compared against the hardness plot.
AB - We have investigated the effect of heat treatment on the microstructure, texture and formability of high-strength aluminium Al2024 sheets of gauge thicknesses 1.27. mm and 2.03. mm. Both optical and electron microscopy were employed to characterise the microstructure. Tensile tests performed at 0°, 45° and 90° to the rolling direction were used as an indication of the anisotropic behaviour of the sheets. The formability of the sheets was assessed by performing stretch forming tests over a hemispherical punch. Comparison of microstructure and material properties indicated an effect of precipitation hardening on the overall anisotropy of the investigated materials. We report an improvement in the total elongation under uniaxial tension with a loss in strength for 2.5. h and 2 days ageing while the ageing treatment for 1 week (peak hardness) resulted in increased strength with a decline in total elongation. The 1.27. mm thick sheet showed better drawability and least tendency to earing than the thicker sheet. The drawability was the highest at 45° to the rolling direction for the as-received material and those that had been aged for 2.5. h and 2 days. Forming limit diagrams derived from the stretch forming tests showed that the 2 days aged sample had the highest plane strain limit making it the most appropriate condition considering that the plane strain is usually the most critical forming strain in stamping applications. In addition, the 2 days aged sample had its plane strain shifted towards the biaxial stretching area which is likely to have a positive effect on some sheet forming applications. Finally, a formability index was calculated and compared against the hardness plot.
KW - Electron backscatter diffraction
KW - Formability
KW - Mechanical characterisation
KW - Precipitation
KW - Transmission electron microscopy
UR - http://www.scopus.com/inward/record.url?scp=84863006560&partnerID=8YFLogxK
U2 - 10.1016/j.msea.2012.04.113
DO - 10.1016/j.msea.2012.04.113
M3 - Article
AN - SCOPUS:84863006560
SN - 0921-5093
VL - 552
SP - 48
EP - 60
JO - Materials Science and Engineering: A
JF - Materials Science and Engineering: A
ER -