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Anand Krishna Kanjarla
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Anand Krishna Kanjarla
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Anand Krishna Kanjarla
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Kanjarla, A. K.
Kanjarla, Anand
Kanjarla, Anand K.
Kanjarla, Anand Krishna
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4 results
Now showing 1 - 4 of 4
- PublicationBiaxial deformation behaviour of duplex stainless steels: Experiments and crystal plasticity based stress predictions(07-02-2023)
;Chalapathi, Darshan ;Bhaskar, Lalith Kumar ;Sivaprasad, P. V. ;Chai, Guocai ;Kumar, RaviBiaxial tensile tests are performed on two phase duplex stainless steel using a newly developed multiaxial testing rig integrated with a digital image correlation mapping facility. A cruciform-shaped specimen geometry is subjected to equibiaxial tensile (EBT) loading, and the load–strain response is captured. Unlike uniaxial tensile testing, a well-defined gauge area is absent in biaxial specimens; hence, stress cannot be estimated directly. Finite element analysis is used to calculate the stress state. The phenomenological finite element model failed to capture the inherent anisotropy of the material; hence, a crystal plasticity finite element based method is used to estimate the stresses. It is observed that the 0.2% proof stress increased, but the strain to failure remained constant in comparison with uniaxial tensile properties. The work hardening behaviour is isotropic similar to that observed during uniaxial testing. The goss and rotated goss orientations in austenite accommodated most of the strain along RD and TD, respectively. During EBT, the change in austenite and ferrite textures is minimal and similar to their single phase counterparts reported in the literature. The EBT test results indicate that the influence of micromechanical interactions between the phases on the work hardening behaviour and texture evolution is weak. - PublicationRole of deformation twinning and second phase on the texture evolution in a duplex stainless steel during cold rolling: Experimental and modelling study(07-04-2020)
;Chalapathi, Darshan ;Sivaprasad, P. V.Deformation twinning is known to be one of the reasons that cause texture transition (copper type to brass type) in single phase fcc materials and is studied extensively. The role of deformation twinning in two phase materials is an area yet to be explored. Similarly in two phase materials, the effect of one phase on the texture evolution of the other phase is not well understood. In this work, a combination of experiments and modelling are used to address their effects on texture evolution in duplex stainless steels. The material is cold rolled to 80% thickness reduction and texture evolution is studied at various strain levels. These are compared with a series of crystal plasticity simulations using the Taylor model and grain interaction based LAMEL model which was extended to a two phase material. Deformation twinning in austenite is incorporated by predominant twin reorientation (PTR) scheme. It is observed that only by accounting for the strong local interactions between the phases, the correct textures are predicted. The texture transition from {001}〈110〉 to {112}〈110〉 orientation observed in ferrite at higher strain levels is attributed to deformation twinning in austenite. A number of simulations with ideal orientations observed in fcc and bcc materials are performed to assess the role of one phase on texture evolution of the other. It is concluded that experimental observations are also required to comment on the dominant phase during texture evolution. - PublicationA crystal plasticity investigation on the influence of orientation relationships on texture evolution during rolling in fcc/bcc two phase materials(01-06-2022)
;Chalapathi, Darshan ;Sivaprasad, P. V.In two phase materials like duplex stainless steels that contain both the phases in nearly equal proportions, the crystallographic texture in the phases is related by special orientation relationship (OR). Most of the studies related to ORs are focused on characterising the type of ORs due to phase transformations and recrystallisation. However, very little is known about the stability of ORs and their role in the texture evolution during deformation. In this work, we present a detailed study on the role of ORs in the texture evolution during rolling in fcc/bcc two phase materials. Three different ORs; Bain, Kurdjumov–Sachs, Nishiyama–Wassermann and two different parent phases; fcc and bcc are considered. Using three-dimensional representative volume element (RVE) based crystal plasticity fast Fourier simulations, we report that the final textures depend strongly on the initial parent phase textures and the existence of an OR, and is independent of the type of the OR. A copper type texture is observed in the fcc phase, when the parent phase is bcc with cube texture. However, a brass type texture is observed when the parent phase is bcc with rotated cube texture. A detailed investigation using a series of bicrystal studies further revealed that even within an OR, the type of Bain variant plays a vital role in the overall texture evolution. It is also observed that there is no marked impact of the initial CRSS ratios and strain hardening on final textures of both the parent and child phases. - PublicationAnisotropic work hardening behaviour in duplex stainless steel under uni-axial loading: Interplay between phase morphology and crystallographic texture(01-08-2022)
;Chalapathi, Darshan ;Sivaprasad, P. V. ;Chai, GuocaiDuplex stainless steels (DSS) are characterised by vivid phase morphology and crystallographic textures. The typical microstructure consists of elongated phases (along rolling direction, RD) stacked alternatively along the normal direction (ND). In this study, uni-axial testing in multiple macroscopic directions is used to explore the anisotropic evolution of work hardening. Crystal plasticity simulations are used to gain insights into the same. The compressive stress and work hardening of samples loaded in the transverse direction (TD) are observed to be higher than those loaded in the RD and ND. Austenite and ferrite developed [110] and [111] parallel to the loading direction type fibre textures during uni-axial compression. The weak austenite texture behaves similarly to its single-phase counterparts regarding reorientation. The plastic anisotropy evolution is aided by the strong ferrite texture, which deviates from its single-phase behaviour. When loaded along TD compared to other directions, microstructural characterisation revealed the formation of deformation twins in austenite and lower effective slip length of both the phases.