Influence of Process Parameters and Grain Size on the Quality of Flexible Forming of Ultrathin 316L Bipolar Plate

Bipolar plate is one of the most important components of proton exchange membrane fuel cells, which has the basic functions of conducting electricity, supporting membrane electrode assemblies, uniformly distributing and isolating reactant gas, circulating coolant, and rapid heat dissipation. In this article, taking the micro runner flexible forming process of 316L stainless steel sheet as the research object, the influence of process parameters on the forming quality of micro flow runners is analyzed. The results show that an increase of the equipment pressure and a decrease of the soft film hardness are conducive to the improvement of the forming depth of a bipolar plate, while the holding time has a minor effect on the forming depth. Under the same loading conditions, the forming depth of a 0.1 mm thick sheet is smaller than that of a 0.075 mm sheet. An increase of the grain size reduces the difficulty of forming, and the larger the grain size, the larger the forming height and runner filling rate. However, with an increase of the grain size, the surface roughness of the bipolar plate increases and the wall thickness of some parts of the runner becomes uneven.