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 and gas, petrochemical and paper industries due to their excellent combination of mechanical and corrosion-resistant properties. A few of the traits of multi-phase materials during deformation are: the existence of a dominant phase, interphase characteristics and their stability, mechanical anisotropy evolution, strain partitioning among the phases and dislocation density evolution. 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 many studies are related to the formation of strain-induced martensite in DSS, the role of deformation twinning (in austenite) on texture evolution is not clear. Orientation relationships (OR) explains the crystallographic relation between a parent and child phase during phase transformation. 30-40% of phase boundaries in DSS have a special OR. However, very little is known about their stability and impact on the texture evolution during deformation. The mechanical anisotropy observed in DSS is due to multiple factors, and it is difficult to quantify and identify the dominating one. The initial crystallographic textures and morphologies of the two phases play a major role in the anisotropy evolution. Also, generally in DSS, austenite and ferrite are soft and hard phases respectively. For this combination, austenite accommodates large strain during early plastic deformation and is slowly transferred to ferrite at higher strain levels. By changing the initial strength of the phases, the individual phase behaviours and their impact on strain partitioning among the two phases are still unclear. In the present study, an effort has been made to answer these concerns using a combination of different types of experiments (and different strain modes like rolling, tension etc.) and various crystal plasticity models (both full-field and mean-field approaches).

In this seminar, experimental and modelling details used in the present study will be presented. The scientific rationale to answer the above concerns will be discussed in detail.