<p>Under plane strain conditions, the leading two terms of the asymptotic stress field near the interface corner of two dissimilar nonlinear elastic–plastic materials with differing hardening behavior were formulated. Assuming that the second material has a higher hardening coefficient (<i>n</i>₂ &gt; <i>n</i>₁), two limiting cases were considered: (1) a rigid case with zero secondary displacement in the second material and (2) a non-rigid case where it equals the first material’s primary displacement. The associated eigenvalues and mixed-mode parameters were then computed for varying angle and hardening levels of the second material. The obtained results exhibited a distinctive characteristic at the angle of 130°, where the mode-mix parameter remains unchanged with varying hardening coefficients. Coefficients for the first two stress terms were determined by minimizing the RMS difference between asymptotic and finite element (FE) stresses under tensile loading. Agreement was assessed across various angles and hardening coefficients. Higher <i>n</i>₁ values improved correlation in the first material by reducing mode-mix contrast in two materials. Larger notch angles and greater hardening in the second material increased deviations, requiring additional asymptotic terms for accuracy.</p>