Texture evolution and grain refinement of ultrafine-grained copper during micro-extrusion

Abstract

Samples of oxygen-free high conductivity (OFHC) coarse-grained (CG) and ultrafine-grained (UFG) copper were micro-extruded to an equivalent strain of 2.8 in one pass at room temperature. Samples of the OFHC copper were annealed at 650 C for 2 h to produce CG copper. Some samples were subsequently processed by equal channel angular pressing of eight passes, route Bc, at room temperature to produce the UFG material. Crystallographic texture and misorientation distributions were obtained locally from EBSD mappings at different radial positions after micro-extrusion. To model the strain path during micro-extrusion, the analytic flow line model of Altan et al. [J Mater. Process. Tech. 33 (1992) p.263] was used and also validated by finite element calculations. Modelling was carried out using the viscoplastic self-consistent (VPSC) model and a recently developed grain refinement model. The results showed large texture variations along the cross-section of the extruded sample for both UFG and CG copper. These cyclic drawing textures in UFG copper were simulated in good agreement with experiments using the presented modelling framework.

Analytical and numerical approaches to modelling severe plastic deformation

“…Inclusion of the grain subdivision effect in terms of the model [454] described above improved the agreement between the calculated and the experimental texture emerging under SPD processing [108]. Figure 53 shows the results of FEM simulations of texture in the form of a {100} pole figure for micro-extrusion of copper [557] vis-à-vis an experimental pole figure. The simulations were based on polycrystal plasticity modelling (the viscoplastic self-consistent (VPSC) approach) and did include grain subdivision.…”

“…We would certainly opt for a crystal plasticity model of the Lebensohn-Tomé kind [94,563], but would include a provision for grain subdivision as proposed in Ref. [557]. The description of strain hardening for individual slip systems of a crystallite would be motivated by a two-internal-variable model presented in Section 3.3.…”

Texture evolution in high-pressure torsion processing

“…It is noted also that grain subdivision (GSD) is an important parameter in the models that tends to improve the agreements between the experimental and predicted textures during SPD processing [245][246][247][248] as is evident from inspection of Figure 39.…”

Asymmetric Rolling of Interstitial-Free Steel Using One Idle Roll

“…It was successfully applied to copper [15][16][17][18] and Al. [19] This modelling approach was also employed in the present case for IF steel for the first time.…”