https://popups.uliege.be/esaform21/index.php?id=4546 Index terms fr 0 https://popups.uliege.be/esaform21/index.php?id=3714 Since its first synthesis in 2004 graphene was characterized intensively and exceptional properties in terms of e.g. mechanical strength, stiffness and electrical as well as thermal conductivity were revealed. These properties make graphene very attractive to be applied as additive in composite materials e.g. to increase strength and conductivity compared to the pure matrix material. In this study graphene nano platelets (GNP) in contents of 0. 5%, 1.0 % and 1.5 % were added to pure (99.7 %) aluminum powder and dispersed via EIRICH mixer method. This method is very appealing since homogenous mixtures can be achieved in significantly lower time when compared to e.g. the ball milling process. After subsequent cold compaction the composite materials were extruded with three different extrusion ratios. The influence of GNP content and extrusion ratio on the specific extrusion pressure is characterized as well the resulting rod surface quality, respectively. The effects of GNP content and extrusion ratio on homogeneity of graphene dispersion in the aluminum matrix, the relative density of the composite as well as hardness were also investigated. Mon, 29 Mar 2021 14:18:38 +0200 Fri, 14 May 2021 15:25:55 +0200 https://popups.uliege.be/esaform21/index.php?id=3714 https://popups.uliege.be/esaform21/index.php?id=3788 Flowforming is an advanced forming technique to produce net shape axisymmetric components, with high dimensional accuracy, based on the simultaneous action of a rotating mandrel and multiple translational rollers. The deformation mechanism has great influence on the uniformity of microstructure, with a gradient in the grain size from the inner to the outer portion of the component cross section, with elongated grains in the rollers feed direction. The highly directional deformation of the microstructure, both along the radial and axial direction, may reach extreme values in the case of large reduction and this aspect may introduce significant uncertainties in the evaluation of the mechanical properties of the final parts (i.e. microhardness, maximum elongation, yield strength) due to the computational methodologies used to estimate the average grain size. The paper focuses on the most frequently used measurement methods to assess the measurement accuracy for the correlation with the local variations of mechanical properties. The reference case for the investigations is the flowforming of AA6082 tubes, processed at different process parameters to change the shape of the grain and the gradient along the radius. Comparisons were carried out with regards to methods that allow measuring the grain size using zero-dimensional features (points), one-dimensional features (lines), and two-dimensional features (areas), respectively with the triple-point count method, the Heyn intercept method and the Jeffries planimetric method. Mon, 29 Mar 2021 14:32:44 +0200 Mon, 12 Apr 2021 11:28:13 +0200 https://popups.uliege.be/esaform21/index.php?id=3788 https://popups.uliege.be/esaform21/index.php?id=1630 Titanium alloys find a wide range of uses, especially in the aeronautic industry because of a combination of favorable specifications in terms of strength-to-weight ratio, corrosion resistance and performance at high temperature. If many works are interested in mechanical properties, as well as microstructure, few of them studied the effect of microstructure on formability. The aim of this work is to study the influence of the microstructure on the formability of β metastable titanium alloys (Ti21S) which are increasingly used in aeronautical applications. For this purpose, two different heat treatments are performed on Ti21S alloy in order to propose different microstructures. Based on uniaxial tensile tests, the elastoplastic hardening behavior and the limit strain in the uniaxial tension state are obtained and allow to determine one point of the forming limit curve (FLC). From these experimental observations, it is shown that the microstructure has an important effect on the formability: precipitation of α phase reduces the formability in comparison with full β phase microstructure. Finally, a finite element M-K model is used and calibrated to predict the whole FLC for the different investigated microstructures. Mon, 22 Mar 2021 20:20:07 +0100 Mon, 12 Apr 2021 11:26:17 +0200 https://popups.uliege.be/esaform21/index.php?id=1630 https://popups.uliege.be/esaform21/index.php?id=737 This paper deals with polyisobutylene (PIB) migration through post-consumer agricultural waste multilayer films based on four linear low-density polyethylene (LLDPE) matrices. Connections between shear, elongational rheology and tack surface properties were revealed for both model and recycled blends. The effects of aging time and temperature were investigated and rationalized, depending on the short- and long-chain branching in LLDPE matrices as well their polyethylene (PE) crystallization. Linear and nonlinear viscoelastic properties were influenced by even small amounts of PIB. This migration also influenced slippage in the steady-flow regime. Transient uniaxial extensional properties were shown to be very sensitive to the presence of PIB, which seems to hold back the PE strain hardening properties. Therefore, the axial force and the surface friction coefficient were determined and discussed in correlation with bulk rheological findings. These results help unveil new insights about the physical mechanisms governing PIB migration with or without fillers inhibiting this migration in recycled films. Sun, 21 Mar 2021 11:43:39 +0100 Mon, 12 Apr 2021 10:54:25 +0200 https://popups.uliege.be/esaform21/index.php?id=737