Fabrication of Bipolar Plates of the Fuel Cell from Stainless Steel 304 by Hot Metal Gas Forming Process

The hot forming of a sheet metal with gas blowing is a novel method in metal forming processes. It has the ability to manufacture products with complex shapes due to high formability and a low flow stress at high temperature. In this research, the forming of bipolar plates with a slotted serpentine pattern by hot metal gas forming process has been investigated experimentally. To this end, 304 stainless steel sheets with 0.12 mm thickness have been used. In order to evaluate the geometric and process parameters effect on forming trend, a convex die that includes three slotted serpentine channel with different widths has been manufactured. Then experiments were carried out at different temperatures, pressures and periods of time. The sheet thinning percentage, the thickness distribution and the depth of die filling have been considered as evaluation criteria of experiments results. The results indicated that the temperature and the forming time have respectively the most and the least effect on the formability. Among three slots with widths of 1, 1.5 and 2 mm, despite slot with 2mm width has the most die filling percentage, the sheet thinning percentage is less than the slot with 1.5 mm width. The most filling percentage of die channel with the amount of %88.8 was observed in the slot with the width of 2 mm at a temperature of 1000 oC, the pressure of 40 bar and forming the time of 30 min.