Abstract
Simulations of the deformation of microstructures at high homologous temperatures have been carried out using a Crystal Plasticity Finite Element (CPFE) model to predict texture and grain structure deformation in Face-Centred-Cubic (FCC) metals deformed under conditions representative of hot forming operations. Results show that the model can quantitatively predict the location and intensity of the main deformation texture components of a AA5052 aluminium alloy deformed at 300 °C under Plane Strain Compression (PSC). Simulations also reasonably predict the range of strain values measured using microgrids in the microstructure of a Fe-30wt%Ni alloy deformed at 1000 °C using a new experimental procedure. However, the model fails to reproduce accurately intra-granular strain distribution patterns. Results at room temperature, after a tensile test carried out inside a Scanning Electron Microscope (SEM) on the same model alloy, show a much closer match between simulation and experimental results. Despite discrepancies for some local deformation features, the model predicts the formation of intense deformation bands running at 45° with respect to the tensile axis and located along the same grain boundaries as in the experiment. Results, therefore, highlight the limitations of deterministic CPFE simulations for situations where the grain size to sample thickness ratio is small and for which the sub-surface grain geometry strongly affects surface strains. They also show that reliable predictions of the statistical response of a polycrystalline aggregate can be obtained for the hot deformation of metals which controls microstructure evolution during the processing of metals.
Highlights
The mechanical properties of metals such as steels and aluminium alloys are dependent on their processing conditions and are a direct result of the microstructure evolution taking place during both hot and cold forming operations
The performance is similar for the two hardening models, the calculated stresses are slightly closer to those measured for the Fe-30wt%Ni curve at room temperature using the Tome model while the prediction at 1000 C is about the same for the two models (Fig. 3(b))
The reliability of Crystal Plasticity Finite Element (CPFE) simulations of the deformation of metals has been assessed in this work with a focus on high temperature applications relevant to the processing of metals during industrial hot forming operations
Summary
The mechanical properties of metals such as steels and aluminium alloys are dependent on their processing conditions and are a direct result of the microstructure evolution taking place during both hot and cold forming operations. Improved computing performance over the past decade has enabled the development of statistically meaningful simulations of the deformation of grain structures in metals using CPFE models These models have been used extensively in published research studies for the prediction of deformation texture and mechanical response of metals at both room (Alharbi and Kalidindi, 2015; Bachu and Kalidindi, 1998; Erinosho et al, 2013; Gerard et al, 2013; Kalidindi et al, 2009; Khan et al, 2015; Sabnis et al, 2013; Sarma and Dawson, 1996; Tamini et al, 2014; Van Houtte et al, 2002; Zhang et al, 2015b) and elevated temperatures (Li et al, 2004; Quey et al, 2012) with good agreement with experimental measurements. Better agreement is usually obtained for the deformation of oligocrystals (Delaire et al, 2000; Kalidindi et al, 2004; Klusemann et al, 2012, 2013; Lim et al, 2011, 2014; Turner et al, 2013; Zhao et al, 2008) for which the geometry of the grain structure is better represented in three dimensions in the simulations
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