Scientific Highlights 2018

22 May 2018

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Mechanical response of stainless steel subjected to biaxial load path changes

In this work, we have enhanced our originally proposed experiment-modeling synergy in Upadhyay et al. Acta Mat. 2016, to capture the stress evolution in the complex cruciform geometry during arbitrary multi-axial load path changes. We perform cruciform simulations using the implementation of the visco-plastic self-consistent (VPSC) model as a user material (UMAT) into the ABAQUS finite element (FE) solver. We also use the Elasto-viscoplastic fast Fourier transform (EVP-FFT) approach to compute yield surfaces. This experiment-modeling synergy is exploited to understand the mechanical response (including the elastic response, Bauschinger effect and hardening) of 316L stainless steel following biaxial load path changes.

9 January 2018

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Suppressed martensitic transformation under biaxial loading in low stacking fault energy metastable austenitic steels

In-situ neutron diffraction studies performed on metastable 201 stainless steel combined with EBSD measurements confirm that ε-martensite is a precursor for α′-martensite during uniaxial and equibiaxial deformation at the same loading rate. In both loading states, the grains that contain martensite belong to orientations for which the leading partial dislocations have higher Schmid factor than the trailing partial dislocations. The martensitic transformation is suppressed during equibiaxial loading as a consequence of the different textures formed during deformation.