Effect of Laser Powder Bed Fusion Process Parameters on Performance of 316L Stainless Steel Bipolar Plates

Due to the advantages of high corrosion resistance, good formability and low cost, 316L stainless steel exhibits great potential in the application of fuel cell bipolar plates. However, retarded by the forming capability of traditional manufacturing methods, it is difficult to fabricate bipolar plates with complex flow-field structures. Therefore, laser powder bed fusion (LPDF) has been employed to fabricate 316L stainless steel bipolar plate, and the influence of laser parameters (laser power and laser scanning speed) on the microstructure, corrosion resistance and interfacial contact resistance (ICR) of LPDFed 316L stainless steel are systematically studied. Besides that, the differences in microstructures and performance between wrought 316L stainless steel and LPDFed 316L stainless steel are compared. The results show that with the increase of laser power or decrease of scanning speed, the density of the LPDFed 316L stainless steel specimens decreased. When the laser power is 300 W, and the scanning speed ranged from 1 500 mm/s to 2 000 mm/s, specimens with densities higher than 99% can be achieved. Compared with the wrought stainless-steel specimens with the microstructures of equiaxed grains, the columnar crystal structures of the LPDFed counterparts facilitated the flow of electron, thus contributing to the reduction of ICR value. In addition, the ICR value of LPDFed 316L stainless steel specimens decreased with the increase of the surface roughness. The results of electro-chemical tests show that the corrosion resistance of LPDFed 316L stainless steel specimens with high relative density was better than that of wrought counterparts. And the corrosion resistance of LPDFed 316L stainless steel specimens gradually deteriorated with the decrease of relative density. Our results revealed that LPBF method can be utilized to fabricate 316L stainless steel bipolar plates for the fuel call application. © 2021 Journal of Mechanical Engineering.