Tensile Behavior and Formability Evaluation of Titanium-40 Material Based on the Forming Limit Diagram Approach
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JMEPEG (2013) 22:2253–2260 DOI: 10.1007/s11665-013-0495-1
Tensile Behavior and Formability Evaluation of Titanium-40 Material Based on the Forming Limit Diagram Approach Apostolos N. Chamos, George N. Labeas, and Dorothea Setsika (Submitted October 10, 2012; in revised form January 8, 2013; published online February 12, 2013) The formability of Titanium alloy sheet material Ti-40 has been experimentally assessed in the present investigation. The investigation is divided into two parts: In the first part, the effect of the strain rate applied during testing, as well as the effect of material axesÕ orientation, on the tensile behavior is evaluated via standard tensile tests. In addition, the hardening characteristics as well as the anisotropy parameters (plastic strain ratio) have also been extracted. In the second part, the formability limits of Ti-40 material are experimentally derived using Nakajima tests and the corresponding forming limit diagrams are compared against other commercially available titanium sheet alloys.
Keywords
anisotropy, FLD, formability, hardening, titanium sheets
1. Introduction Due to their high strength to weight ratio, excellent corrosion resistance, and high operating temperature capability, titanium alloys have been used for aeronautical applications for several decades (Ref 1-3). The family of titanium alloys offers a wide spectrum of strength values as well as many combinations of strength and fracture toughness values. This characteristic permits an optimized alloy selection, which can be tailored for a critical component based on whether its service life is controlled by strength and fatigue or toughness and crack growth. The technologies currently applied by the aircraft industry to shape titanium into complex components basically include deep drawing, hot forming, super-plastic forming (SPF), and hydroforming. Handmade components may also be found in some cases. The selection of the appropriate technology for each application depends on shape complexity and material considerations. Parts with very demanding geometries and / or parts manufactured using Ti alloys with high strength (e.g., Ti 6-4, Ti 6-2-4-2) are produced by SPF or hot forming. Representative examples of this type of application in the aeronautic industry are the air inlet bulkheads, after pylon fairing parts, and turbine components. On the other hand, parts made of low to medium strength alloys (e.g., Ti-grade 2, grade 4, and grade 9) can be shaped by cold forming. Representative examples of such cold forming applications include pylon fairings, system supports, Apostolos N. Chamos, George N. Labeas, and Dorothea Setsika, Laboratory of Technology & Strength of Materials, Department of Mechanical Engineering and Aeronautics, University of Patras, 26500 Rion, Greece. Contact e-mail: [email protected].
Journal of Materials Engineering and Performance
and air collector parts. Furthermore, during the last few years, Asymmetric Incremental Sheet Forming (AISF) process has gained an increasing interest as a low co
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