Understanding Size Effects and Forming Limits in the Micro-Stamping of Industrial Stainless Steel Foils

Matthias Weiss,Peng Zhang,Peter D Hodgson,Daniel E Wilkosz,Bernard F Rolfe,Michael P Pereira

doi:10.3390/met11010038

Matthias Weiss, Peng Zhang + Show 4 more

Open Access

https://doi.org/10.3390/met11010038

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Journal: Metals	Publication Date: Dec 26, 2020
Citations: 9	License type: CC BY 4.0

Affiliation: Deakin University, Ford Motor Company (United States)

Abstract

This study investigates the effect of grain size and composition on the material properties and forming limits of commercially supplied stainless steel foil for bipolar plate manufacture via tensile, stretch forming and micro-stamping trials. It is shown that in commercially supplied stainless steel the grain size can vary significantly and that ‘size effects’ can be influenced by prior steel processing and composition effects. While the forming limits in micro-stamping appear to be directly linked to the plane strain forming limits of the individual stainless steel alloys, there was a clear effect of the tensile anisotropy. In contrast to previous studies, forming severity and the likelihood of material failure did not increase with a decreasing channel profile radius. This was related to inaccuracies of the forming tool profile shape.

Highlights

Polymer electrolyte membrane (PEM) fuel cells have received considerable attention as a clean energy source and are of great interest to the automotive industry [1]
This study investigates for the first time the effect of prior processing, composition and microstructure on the mechanical properties of industrially supplied stainless steel foil and establishes the link with material behaviour and forming limits in micro-stamping
Tensile and stretch forming limit trials were performed on five commercial stainless steels and two heat treated conditions

Summary

Introduction

Polymer electrolyte membrane (PEM) fuel cells have received considerable attention as a clean energy source and are of great interest to the automotive industry [1]. Stainless steels have received the most attention [4] while there is increasing interest in the use of titanium foils [5]. Several technologies have been developed to manufacture metal bipolar plates from stainless steel foil. These include micro electrical discharge machining (μEDM) [9], lithography galvanic moulding (LIGA) [10], electrochemical micro-machining (EMM) [11], hydroforming [12], and micro roll forming [13]. The micro-stamping process [14] promises the most economical solution, combined with easy and rapid implementation

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Conclusion