Uniaxial Tensile Behaviour of 75μm Thick Stainless-Steel Foils

Lin Wang

doi:10.5755/j01.mech.26.3.23417

Abstract

Accurate knowledge about tensile behavior of thin stainless-steel foils at micro/meso scale is of great importance for potential industrial applications. In this work, two 75μm thick AISI 304L and 439 stainless-steel foils were tested under uniaxial tension. Digital image correlation (DIC) based strain measurement method was applied to characterize the plastic deformation of foil specimen. The stress-strain relations of foil specimens were identified from DIC-based strain measurement and compared with the results derived from crosshead displacement. It is found that the applied DIC method can more precisely characterize the mechanical behaviors of foil materials at small size scale. Fracture surface of foil specimens were also characterized. The material microstructures are found have predominant effect on tensile behaviors of foil materials.

Highlights

The average grain size of AISI 304L foils after annealing is 16.8 μm including twins or 36.8 μm excluding twins based on electron backscatter diffraction (EBSD) data analysis (Fig. 2, c)
The textures of as-received foils are shown in Fig. 3 by inverse pole figures (IPF)
The true stress-strain curve of as-received AISI 439 foil specimens in the transverse direction is about several degrees higher compared with the curves obtained from as-received AISI 304L foil specimens aligned to the rolling direction

Summary

Microstructural characterization

A, twins appear intensively within grains for the FCC AISI 304L foil so the average grain size is 3.76 μm considering twins or 7.13 μm if disregarding twins. Twins are hardly observed in the as-received BCC AISI 439 foil (Fig. 2, b) with average grain size of 19.23 μm. The average grain size of AISI 304L foils after annealing is 16.8 μm including twins or 36.8 μm excluding twins based on EBSD data analysis (Fig. 2, c). The AISI 439 foil after annealing has an average grain size about 21.5 μm (Fig. 2, d), closing to the grain size of as-received foil. The textures of as-received foils are shown in Fig. 3 by inverse pole figures (IPF). Limited change in textures is found for both foil materials after heat treatment

Plastic deformation

Fracture morphology

Effect of strain measurement methods

Effect of microstructures

Conclusions

Summary