Synergetic strengthening of layered steel sheet investigated using an neutron diffraction tensile test

Kim, J. G.*; Bae, J. W.*; Park, J. M.*; Woo, W.*; Harjo, S.   ; Chin, K.-G.*; Lee, S.*; Kim, H. S.*

Synergetic strengthening induced by plastic strain incompatibility at the interface, and the resulting extra geometrically necessary dislocations (GNDs) generated during plastic deformation, were investigated to understand the origin of extra strength in heterogeneous structured (Hs) materials. The mechanism of extra GND generation in twinning-induced plasticity (TWIP)-interstitial free (IF) steel layered sheet was quantitatively analyzed by conducting neutron scattering tensile test. The extra GNDs can be correlated with the back-stress evolution of the HS materials, which contributes to the strength of layered materials. Because of the back-stress evolution caused by load partitioning, the strength of TWIP-IF layered steel is higher than the strength estimated by the rule-of-mixtures.