Local behavior of an AISI 304 stainless steel submitted to in situ biaxial loading in SEM

Abstract

The microstructural response of a coarse grained AISI 304 stainless steel submitted to biaxial tensile loading was investigated using SEM and X-ray diffraction. The specimen geometry was designed to allow for biaxial stress state and incipient crack in the center of the active part under biaxial tensile loading. This complex loading was performed step by step by a micromachine fitting into a SEM chamber. At each loading step FSD pictures and EBSD measurements were carried out to study the microstructural evolution of the alloy, namely grain rotations and misorientations, stress-induced martensite formation and crack propagation. According to their initial orientation, grains are found to behave differently under loading. Approximately 60% of grains are shown to reorient to the [110] Z orientation under biaxial tensile loading, whereas the 40% left undergo high plastic deformation. EBSD and XRD measurements respectively performed under loading and on the post mortem specimen highlighted the formation of about 4% of martensite.

Large-area, high-resolution characterisation and classification of damage mechanisms in dual-phase steel using deep learning

“…Strains in post-mortem experiments were measured as global strains over the deformed sample area based on the elongation between two markers in the undeformed parts of the sample. For in-situ tensile tests, a smaller deformation stage (Proxima 100, MicroMecha SAS, France [32]) was used. In-situ deformation strains, in addition to the initially applied pre-strain of the samples, were extracted from the deformation of the microstructure in the observed panoramic images by digital image correlation (DIC) and averaged over the observed area of 500 x 500 µm.…”

A High Resolution Digital Image Correlation Study under Multiaxial Loading

“…To gain insight into the dependence of the mechanical behavior on the strain paths, several biaxial deformation devices, using cruciform-shaped samples, have been employed in combination with microscopy, X-ray and neutron diffraction methods [4,[10][11][12][13][14][15][16][17]. Significant work has been done to optimize the cruciform geometries in order to reach high plasticity at the center, avoid fracture at the cruciform arms, reduce the stress heterogeneity in the center of the cruciform and prevent shear loading in the cruciform arms [18].…”

Investigations of size effect on formability and microstructure evolution in SS304 thin foils

“…For austenitic steel, it has been reported in literature that the grains having initial orientation close to [111]|| ND and [101]|| ND undergo global rotation and reorient towards or close to [101] || ND direction with deformation, whereas grains having other initial orientations undergo severe plastic deformation and develop high intragranular misorientations during deformation. 28 In this study, the 30 µm foil exhibits a higher fraction of [101]|| ND (according to the colour coding of the IPF legend) as shown in Figure 7. With the increase in foil thickness, the intensity of [101]|| ND orientation gets diluted and the number of other oriented grains increases.…”