Investigation of strain-hardening rate on splined mandrel flow forming of 5052 and 6061 aluminum alloys

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Vol. 532; pp. 287 - 294
• Main Authors: Haghshenas, M., Wood, J.T., Klassen, R.J.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 2012; Elsevier
• Subjects: Alloys; Aluminum alloys; Aluminum base alloys; Applied sciences; Exact sciences and technology; Forming; Indentation hardness; Magnesium; Metals. Metallurgy; Other forming methods; Plastic deformation; Plastic strain; Production techniques; SMFF; Strain; Strain hardening; Aluminum alloys; Plastic deformation; Indentation hardness; SMFF; Strain hardening; Annealing; Aluminium base alloys; Plastic flow; Stress strain relation; Deformation ratio; Yield criterion; Hardness; Indentation; Hydrospinning; Strain distribution; Yield strength; Strain rate
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2011.10.094

► A 47% higher post SMFF yield stress in the 5052-O alloy compared with 6061-O. ► Larger the maximum local equivalent plastic strain in the SMFF 5052-O alloy than SMFF 6061-O alloy. ► Larger point-to-point variance in the local plastic strain in the SMFF 5052-O alloy than SMFF 6061-O alloy. ► Higher grain-to-grain variability in the plastic strain on the SMFF 5052-O alloy than 6061-O alloy. The effect of the strain-hardening rate on the plastic strain distribution in parts made from aluminum alloys by the Splined Mandrel Flow Forming (SMFF) process was investigated. Parts were made from annealed 5052 and 6061 aluminum alloys by SMFF with different levels of average work piece thickness reduction, from 20 to 60%. The average yield stress for the 5052 and the 6061 alloys increased by 187% and 87% after SMFF (60% thickness reduction). The larger increase in yield stress of the 5052 work piece is attributed to its higher strain-hardening coefficient resulting from it containing higher levels of solid-solution Mg compared to the 6061 alloy. While the magnitude of the average von-Mises equivalent plastic strain through the thickness of the SMFF work piece was essentially the same for both alloys, the local equivalent plastic strain near the surface of the work piece and the point-to-point scatter in the measured plastic strain was greater in the 5052. This is attributed to the effect of the increased solid-solution Mg content localizing plastic flow. These findings illustrate the role of solid solution strengthening additions, in this case Mg, on increasing the average mechanical strength but also increasing the extent of local plastic strain variability in aluminum alloy material subjected to intensive plastic forming operations such as SMFF.