Low-carbon 10 wt.% Ni steels with an appropriate quench-lamellarization-tempering (QLT) heat treatment achieve an excellent combination of high-strength, high-toughness, and projectile ballistic resistance due to a high-volume fraction of thermally stable retained austenite. Research has demonstrated that core-shell MC/M2C carbides (M is Mo, Cr, V) form during the QLT treatment. It is unknown whether these metal carbides play any significant role in austenite formation. We have designed a heat treatment that forms carbides with different sizes and distributions, within a martensitic matrix prior to the lamellarization step, which permits studying the role of carbides in austenite formation and possibly altering the size and distribution of austenite grains, to further improve the mechanical properties of this steel. Herein, we utilize experimental characterization techniques, scanning electron-microscopy, synchrotron x-ray diffraction, atom-probe tomography, and electron backscatter diffraction, to follow the kinetics of phase transformations and the resulting microstructural features at different hierarchical length-scales.