ORIGINAL ARTICLE Superplastic-like forming of non-superplastic AA5083 combined with mechanical pre-forming Jun Liu & Ming-Jen Tan & Yingyot Aue-u-lan & Anders E. W. Jarfors & Kai-Soon Fong & Sylvie Castagne Received: 28 January 2010 / Accepted: 7 May 2010 / Published online: 23 May 2010 # Springer-Verlag London Limited 2010 Abstract Superplastic forming has been considered as an attractive process in the automotive and aerospace indus- tries. However, the disadvantages of slow forming rate, high-temperature requirement, poor thickness distribution, and expensive base material have hindered its widespread use for high production volume. In this paper, the non- superplastic grade of 5083 aluminum alloy (AA5083) sheets with thickness of 3 mm was employed in a superplastic-like forming process, which is a combination of drawing (mechanical pre-forming) and superplastic forming (blow forming). Experimental trials were con- ducted to verify the possibility of improving the forming rate and lowering the process temperature. The blank was firstly pre-formed during the mechanical pre-forming phase. As a result, some part of material along the flange area was introduced inside the deformation cavity in advance of the blow forming phase. Secondly, argon gas was applied on the sheet, which would be deformed to come into contact with the inner die surface at the end of pressure cycle. It took only 8 min for the blow forming phase, and the process achieved an almost fully formed part at 400°C. The minimum thickness occurred at the inward corners, and the maximum thinning of the formed part was 54%. Grain growth and cavitation were found from the microstructure observations. Keywords Superplastic forming . Non-superplastic . Mechanical pre-forming . Thermomechanical processing 1 Introduction Superplastic forming (SPF) is a process by which a sheet is formed at high temperature (typically more than 0.75T m , where T m is the melting temperature in Kelvins) by using gas pressure introduced into a die cavity. To produce complex parts successfully using this process, a material with superplasticity is required due to its high formability in the specific range of temperatures and thermal stability (no large grain growth) at high temperature. Because of the advantages of forming large and complex pieces in one operation, SPF is considered as a growing technique in several sectors, including aerospace, automotive, and architectural industries [1, 2]. The major drive on this process has emphasized on the development of superplastic materials rather than improv- ing the process. The Al materials largely comply with the SPF process requirements, such as fine grain size, high microstructure stability with respect to grain growth, and high purity of the structure. So far, a lot of research papers have indicated superplastic properties in aluminum, tita- nium, magnesium, duplex stainless steels, and tin-lead alloys, which can be used for SPF applications [3-9]. As an alloy with high corrosion resistance and moderate to good mechanical strength (155–300 MPa), AA5083 with superplasticity grade is a commonly used material for SPF applications [10]. However, this material is specially produced, which limits its usage only to SPF because of the high manufacturing cost [2]. Most of the prior SPF processes were conducted at a temperature around or higher than 500°C, which also introduced many problems, such as J. Liu . M.-J. Tan (*) . S. Castagne School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore 639798, Singapore e-mail: mmjtan@ntu.edu.sg Y. Aue-u-lan . A. E. W. Jarfors . K.-S. Fong Singapore Institute of Manufacturing Technology, Singapore 638075, Singapore Int J Adv Manuf Technol (2011) 52:123–129 DOI 10.1007/s00170-010-2729-9