Duplex stainless steels (DSS) are high alloyed materials containing comparable proportions of austenite (fcc) and ferrite (bcc) at room temperature. DSS are finding an increased number of applications in the oil \& gas, petrochemical and paper industries due to their excellent combination of mechanical and corrosion-resistant properties. A few unique traits of DSS are the banded microstructure, existence of a phase with strong texture, a significant fraction of phase boundaries, and phases with different initial hardness and strain hardening capabilities. The deformation of austenite in DSS is mainly governed by its stacking fault energy (SFE), and the deformation in ferrite is predominantly by slip. While the strain-induced phase transformation of austenite to martensite (observed in low to medium SFE materials) is well established, the role of deformation twinning on texture evolution is unclear. Phase boundaries make up almost half of all the interfaces, of which 30-40% have a special orientation relationship (OR). Very little is known about the stability of OR and impact of individual variants on texture evolution during deformation. DSS show significant anisotropy during work hardening that is attributed to multiple factors, and it is difficult to quantify and identify the dominating one. The initial crystallographic textures and phase morphologies are expected to play a significant role in the plastic anisotropy evolution. Generally in DSS, austenite and ferrite are the soft and hard phases, respectively. For this combination, austenite accommodates large strain during early plastic deformation. At higher strains, with saturation in the work hardening capability of austenite, ferrite accommodates more strain. By changing the initial strength of the phases, their deformation behaviour and impact on strain partitioning are still unclear. In the present thesis, an effort has been made to answer these concerns using a combination of different types of experiments (using multiple strain modes like rolling, uniaxial and biaxial loading) and crystal plasticity models (using both mean-field and full-field approaches).

Although the ferrite textures deviate from its single phase behaviour in the presence of ferrite, the behaviour of austenite is comparable to that of its single phase counterpart. During rolling, it was seen that delayed deformation twinning stabilised the goss component in austenite and is atrtibuted for texture transition from {001} to {112} orientation in ferrite. Simualtions showed that strong parent textures led to differing child textures during cold rolling based on the type of interphase OR. The final textures were significantly influenced by the behaviour of individual OR variants. Special ORs were observed to be unstable during cold rolling. During uniaxial loading, a significant anisotropy in the work hardening behaviour was observed due to the extreme morphological features and deformation twinning in austenite. In situ neutron diffraction studies revealed that austenite yielded first and accommodated majority of the strain. The (200) planes in ferrite shared the strain (with austenite) at higher stresses after the strain accommodation capability of (211) and (110) planes in ferrite were reduced.