Deformation and texture evolution of OFHC copper during dynamic tensile extrusion
Artikel i vetenskaplig tidskrift, 2015

During dynamic tensile extrusion (DTE) the material is subjected to a complex deformation history, including high strain rates, large strains and elevated temperatures. This technique provides unique means to explore material performance under extreme conditions. In this work, the microstructural evolution of 99.98% commercially pure copper during the DTE test was investigated by means of electron backscatter diffraction (EBSD). The investigation was focused on the segment of the extruded jet that remained in the die, since numerical simulation showed that material points along the longitudinal axis of such segment correspond to different stages of a common temperature compensated deformation history. Therefore, post mortem microstructure information extracted at different locations along the center line is equivalent to in situ real-time measurement during the deformation process. EBSD investigations along the center line showed a progressive elongation of the grains, and an accompanying development of a strong 〈0 0 1〉 + 〈1 1 1〉 dual fiber texture. Meta-dynamic discontinuous dynamic recrystallization (DRX) occurred at larger strains, and it was demonstrated that nucleation occurred during straining, while subsequent grain growth took place during post-deformation cooling in the die. According to strain energy minimization arguments, the recrystallization resulted in an increased 〈0 0 1〉 texture component. The critical strain for recrystallization was well predicted from a power-law dependence on the Zener–Hollomon parameter, including grain size dependence and a temperature dependent activation energy. In addition, it was shown that 〈0 0 1〉 and 〈1 1 1〉oriented grains develop different dislocation substructures during straining, exhibiting elongated cells/micro-bands and typical cell structures, respectively. The present results also confirm that dynamic tensile ductility increases with decreasing initial grain size as a result of grain refinement and lowering of dislocation and twin densities during DRX.

DRX

Copper

Dynamic tensile extrusion

EBSD

Texture

Författare

Magnus Hörnqvist

Chalmers, Teknisk fysik, Materialens mikrostruktur

Nooshin Mortazavi Seyedeh

Chalmers, Teknisk fysik, Materialens mikrostruktur

Mats Halvarsson

Chalmers, Teknisk fysik, Materialens mikrostruktur

Andrew Ruggiero

Universita di Cassino e del Lazio Meridionale

G. Iannitti

Universita di Cassino e del Lazio Meridionale

Nicola Bonora

Universita di Cassino e del Lazio Meridionale

Acta Materialia

1359-6454 (ISSN)

Vol. 89 163-180

Ämneskategorier

Maskinteknik

Materialteknik

Annan teknik

Styrkeområden

Materialvetenskap

DOI

10.1016/j.actamat.2015.01.053

Mer information

Senast uppdaterat

2018-10-15