Experimental investigation and modelling of hot forming B4C/AA6061 low volume fraction reinforcement composites

This paper presents an experimental investigation of the hot deformation behaviour of 15%
B4C particle reinforced AA6061 matrix composites and the establishment of a novel corresponding
unified and physically-based visco-plastic material model. The feasibility of hot
forming of a metal matrix composite (MMC) with a low volume fraction reinforcement has
been assessed by performing hot compression tests at different temperatures and strain rates.
Examination of the obtained stress-strain relationships revealed the correlation between
temperature and strain hardening extent. Forming at elevated temperatures enables obvious
strain rate hardening and reasonably high ductility of the MMC. The developed unified material
model includes evolution of dislocations resulting from plastic deformation, recovery
and punching effect due to differential thermal expansion between matrix and reinforcement
particles during non-steady state heating and plastic straining. Good agreement has been
obtained between experimental and computed results. The proposed material model contributes
greatly to a more thorough understanding of flow stress behaviour and microstructural
evolution during the hot forming of MMCs.