Fabrication of very-high-strength pure copper with fine grain structure through multi-axial diagonal forging

This paper demonstrates the application of multi-axial diagonal forging (MADF) for fabricating very-high-strength pure Cu with a fine-grained microstructure. Pure Cu subjected to 1 MADF cycle, which comprises 6 passes of multi-axial forging operations and 6 subsequent passes of diagonal forging operations, has a tensile yield strength, ultimate tensile strength, and elongation of 397 MPa, 436 MPa, and 15.7%, respectively. This high strength is attributed to the combined effects of considerably refined grains resulting from continuous dynamic recrystallization during MADF and high dislocation density induced by large imposed strains. With increasing number of MADF cycles, the average grain size and microstructural homogeneity of the multi-axial diagonal forged samples gradually decreases and improves, respectively.