Finite element simulation of warm deep drawing of aluminium alloy sheet when accounting for heat conduction

A New Constitutive Model for the Finite Element Simulation of Local Hot Forming of Aluminum 6xxx Alloys

“…[2] without introducing the kinetic equation (Eq. [1]) at all. This is an acceptable approximation only at low temperatures for which the strain rate dependency of the flow stress is small, i.e., _ e p _ e 0 1=m % 1; 8_ e p ; as illustrated in Figure 1.…”

“…The parameter m can thus be estimated from tensile testing with a jump in strain rate at different temperatures, assuming that the hardening stress, i.e., the other factor in Eq. [1]r ð Þ remains approximately constant during the transient time associated with the increase in strain rate from the first constant value to the other. The factorr can then be calculated by Eq.…”

“…[1] and [2] can easily give a reasonably good fit to experimental data at lower temperatures, [6,8] they tend to overestimate the dislocation density and thereby r^andr at higher temperatures. To illustrate this problem, we start by noting that the factor _ e p _ e 0 1=m in Eq.…”

“…To illustrate this problem, we start by noting that the factor _ e p _ e 0 1=m in Eq. [1] mainly represents the strain rate sensitivity. The parameter m can thus be estimated from tensile testing with a jump in strain rate at different temperatures, assuming that the hardening stress, i.e., the other factor in Eq.…”

“…Among these we find the local hot forming process in which the material is subjected to local heating while being simultaneously deformed, either thermally induced or by an additional mechanical load. By hot forming, the softening behavior that some alloys exhibit at elevated temperatures is exploited in order to effectively carry out certain critical forming operations (e.g., deep drawing [1] or hydroforming [2] ) or controlling the local microstructure, [3] and thus the local properties of the final component. Moreover, the use of local hot forming also allows drawing without die or backing tool, which is a great advantage when extruded sections are deformed.…”