Tribological shifting phenomena during automatic multistage cold forging of an automotive Al6082-T6 steering yoke

Abstract

A new tribological shifting phenomenon is presented during automatic multistage cold forging (AMSCF) of an automotive Al6082-T6 steering yoke. A compression test reveals the flow behavior of the Al6082-T6 alloy in the cold-forging temperature range, which is described by the generalized power-law model. It is shown that the fitted and experimental flow curves are in good agreement. The flow stress at strains higher than the limit reliable strain of 0.5 is extrapolated to overcome the limitations of the cylinder compression test; the validity of this extrapolation is verified. Accurate flow information reveals not only unstable plastic deformation of the alloy but also the causes of the peculiar flow-coupled tribological shifting phenomenon empirically apparent during AMSCF. This phenomenon is numerically explained. During AMSCF, a tribological effect caused by such shifting drastically increases friction and can predominate when the material exhibits macroscopic flow instability attributable to flow softening owing to the viscous heating. © 2024 The Society of Manufacturing Engineers