Comparison of a low carbon steel processed by Cold Rolling (CR) and Asymmetrical Rolling (ASR): Heterogeneity in strain path, texture, microstructure and mechanical properties

Evaluation of dieless hydroforming process for manufacturing of variable cross section tubular structures

“…The theory of cold forming suggests that the grain refinement would occur at the application of continuous load at room temperature due to continuous deformation and generation of new grains from the large grains by the progressive increase of high angle grain boundary (HAGB) misorientations by the movement of heterogeneously distributed geometrically necessary dislocations (GNDs) across the material thickness. 20 The progressive increase in misorientation would results in lowering of primary (ferrite) grain size as occurred in the current study. After 30 bar, the primary ferrite grains experience unexpected grain boundary (GB) expansion and large density of immobile GNDs 21 at 40 bar and 50 bar (Figures 6(e) and (f)).…”

“…The cold deformation, as discussed earlier, which is the key mechanism for grain refinement, resulting in the increment of strength up to 30 bar and due to the grain boundary expansion at higher pressure resulting in softening and lower strain hardening behaviour. 20,21 It is also to be noted that the samples at 30 bar show higher UTS and YS values compared to as-received sample (Table 6). The as-received samples are annealed and having coarse grain structure provide lower strength according to the Hall-Petch correlation.…”

“…The rigidity of 2.5 mm thick sheets is higher than that of lower thickness sheets, allowing them to sustain pressure for extended periods of time and likely enhancing the strain hardening mechanism to reduce grain size. 20,22 Higher strain hardening rates at lower thicknesses, on the other hand, may increase the density of immobile dislocations within the rapidly deformed grains, resulting in higher plasticity of the material. 21 The tensile test of hydroformed samples has been performed to understand the strength behaviour and also compared to the as-received material and the results are tabulated in Table 6.…”

Strengthening of Duplex Stainless Steel Processed by Equal Channel Angular Pressing (Ecap)

“…This figure shows how ECAP deformation increases the fraction of low angle grain boundaries (LAGB) reaching 21% and 30% fractions after 1 and 2 ECAP passes. Several authors have established that this behavior obeys the continuous dynamic recrystallization (CDRX) phenomena [50][51][52][53][54]. In this mechanism, new grain boundaries are generated from dislocation walls, which can evolve into high angle grain boundaries (HAGB), increasing their misorientation by absorbing more dislocations giving rise to small grains without nucleation as traditionally observed in the discontinuous dynamic recrystallization (DDRX).…”

“…Thus, Fig. 4a indicates that in the as-received condition the material presents a typical extrusion or lamination texture found in metallic materials produced as bars or plates [50,54]. After the first and second ECAP passes, Fig.…”