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Influence of Strain Amplitude on the Microstructural Evolution and Flow Properties of Copper Processed by Multidirectional Forging
Author(s) -
Flausino Paula Cibely Alves,
Nassif Maria Elisa Landim,
Bubani Franco de Castro,
Pereira Pedro Henrique R.,
Aguilar Maria Teresa Paulino,
Cetlin Paulo Roberto
Publication year - 2020
Publication title -
advanced engineering materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.938
H-Index - 114
eISSN - 1527-2648
pISSN - 1438-1656
DOI - 10.1002/adem.201901510
Subject(s) - misorientation , materials science , copper , composite material , amplitude , forging , flow stress , grain size , metallurgy , plasticity , microstructure , dislocation , grain boundary , physics , quantum mechanics
Commercial‐purity copper (99.8%) is processed by multidirectional forging (MDF) using strain amplitudes per compression (Δ ε ) of 0.15 and 0.30, leading to accumulated strains ( ε ) of up to ≈10.8. It is shown that increasing the accumulated strain causes continuous reactions at the substructural level, involving the progressive evolution of dislocation arrangements toward structures having high misorientation angles. This evolution depends upon the strain amplitude in MDF processing and is characterized by the fragmentation of the original grains due to formation and intersection of micro shear bands (MSBs) assisted by dynamic recovery processes. Higher Δ ε enhances the “monotonic” character of processing, resulting in a higher fraction of MSBs and band intersections, increased work hardening, flow stresses, and dislocation density, lower cell/subgrain and grain sizes, and faster grain refinement kinetics, compared with MDF under lower Δ ε . The yield strength of copper, measured along a direction orthogonal to that of the previous compression step, is lower than the flow stress at the end of this compression step, and this behavior becomes more prominent with increasing ε and Δ ε .