An analysis and investigation on sheet metal formability of tantalum

The Tantalum is one of the refractory metals with the melting point of 2996ºC, mostly used in industries where high temperature is needed. In this research the formability of pure tantalum has been investigated. For this purpose the Erichsen test was carried out on the tantalum sheets with thicknesses of 0.1, 0.2 and 0.3 mm. Also the compression test has been carried out on the tantalum cylindrical specimens with diameter and height of 6 mm and 9 mm, respectively. Whole materials were annealed before the tests. To observe the results of annealing, before and after the annealing the Vickers micro hardness test and metallography process was performed. For Erichsen test, circles with diameter of 3mm have been plotted on the surface of sheets. Erichsen test was performed on samples and after transformation of circles to ellipses, the diameters of these ellipses near fracture area, was measured using a digital microscope and strains were calculated as well. The strain-hardening exponent, n, and strength coefficient, k, for tantalum is determined. Finally by using the results of tests, the forming limit diagram (FLD) for tantalum has been plotted. Then diagram obtained from experimental results has been compared with the diagram based on Kuhn, Caddle and Swift theories. The results indicate good similarity of plotted diagrams.

کلیدواژه ها:

Tantalum ، FLD ، Erichsen test ، Compression test