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MM: Fachverband Metall- und Materialphysik

MM 28: Poster Session II

MM 28.31: Poster

Dienstag, 17. März 2015, 18:30–20:30, Poster E

Flow curve simulations of aluminum binary alloys — •Volker Pankoke¹, Volker Mohles¹, Philipp Schumacher², and Benjamin Milkereit² — ¹RWTH Aachen Univerity, Institute of Physical Metallurgy and Metal Physics, Aachen, Germany — ²University of Rostock, Chair of Materials Science, Rostock, Germany

A work hardening model based on four different types of dislocation densities is used to calculate flow curves of aluminum alloys in a temperature range from 30 to 500^∘C and strain rates of 0.1 and 0.001s⁻¹. Experimental input comes from stress strain curve measurements on Al-Si alloys with different Si content and precipitates, depending on the cooling rate settings of the alloy. During cooling the precipitation behavior of the samples is investigated by Differential Scanning Calorimetry (DSC) to measure and control precipitation. To describe the plasticity of the alloys with the Four Internal Variable Model (4IVM), solute atoms must be taken into account. The corresponding formulation of the previous model 3IVM+ failed for the Al-Si alloys under consideration. Several approaches were tested in order to develop a new model for solid solution strengthening. Among them are the assumption of a short range order stress which depends on temperature but not on the different strain rates. Additionally the effect of Cottrell-clouds is implemented in the model, which leads to a range of abnormal thermal dependence of the flow stress and to jerky flow under certain conditions. The simulated flow curves and their serrations are compared to the measurements.