HighlightsLow pressure infiltration is suitable to produce MMSFs with hollow iron spheres.The MMSFs showed plastic yielding and long, slowly ascending plateau region.The matrix and the heat treatment strongly influence the properties of the MMSFs.The full-scale FEM model gives excellent agreement compared to the measured values. Highlights (for review) *Manuscript Click here to view linked References AbstractAluminium alloy syntactic foams reinforced with iron hollow spheres were produced by low pressure, liquid phase inert gas infiltration technique. Four Al alloys (Al99.5, AlSi12, AlMgSi1 and AlCu5) and Globomet grade iron hollow spheres were used as matrix and reinforcing material, respectively. The produced composite blocks were characterised according to the ruling standard for compression of cellular materials in order to ensure full comparability. The compressive test results showed plastic yielding and a long, slowly ascending plateau region that ensures large energy absorption capability. The proper selection of the matrix material and the applied heat treatment allows for a wide range of tailoring of the mechanical properties. For design purposes, the full-scale finite element method (FEM) model of the investigated foams was created and tested on Al99.5 matrix foams. The FEM results showed very good agreement with the measured values (typically within 5% in the characteristic properties and within 10% for the whole compression curve).

Al 7075 alloy was equal and differential speed rolled according to various deformation routes. In these routes the sheets were rotated around different axes between subsequent passes of rolling. The mechanical properties and the microstructure of the specimens processed by various routes were compared. It was found that while the strength values were irrespective of the rolling routes, the ductility depends strongly on the deformation method. The differences in the mechanical behavior were explained by the edge/screw character in the dislocation structure.

The present study focus on the influence of multiple forging (MF)

No abstract

In designing of plastic metalworking technologies, one determining amount used is the flow stress (kf ) of the material to be formed. A few experimental methods are used to measure it, but in all case it is intended to establish a specific stress and strain state in the whole volume of the specimen, or at least in its majority. In our work the limitations of upsetting in axial symmetrical and plane strain states were investigated by FE modeling and experimental methods within cold working conditions. Both methods were executed on traditional testing machines and Gleeble 3800 thermo-mechanical simulator. It was intended to determine the flow stress up to as high strain values as possible. The processing of the experimental results showed, reliable flow stress values were obtainable in the equivalent strain range of 0 to 3 using the step-by-step upsetting in plane strain, and in the 0 to 1.2 range by cylindrical upsetting.

The method of severe plastic deformation is often used to produce bulk ultra-fine grained materials. Numerous methods exist, which are able to produce ultra fine grained materials. Investigated the mechanical schema of these procedures, we searched for such attributes, which characterize the mentioned techniques. By our previous researches can be established, that for these techniques shear deformation as well as the so-called non-monotonic deformation are characteristic. In this paper a degree of non-monotonity is presented, which is an appropriate measure to characterize the forming processes. Besides this the combined Euler – Lagrange method is showed, which is appropriate to obtain a continuous velocity field from finite element analysis. Eventually the mechanical analysis of the extrusion, conventional and asymmetric rolling is showed with respect to the non-monotonity.

In order to meet environmental standards, a finishing laser treatment on the honed cylinder bores of V-engine blocks was performed. Samples of laser-treated cast-iron cylinder bores with lamellar graphite were taken. Scanning electron micrographs were taken on cross-sectioned specimens with a scanning electron microscope/focused ion beam dual beam instrument in order to evaluate the microstructure and grain size of the laser-treated layer. Specimens were found to be ultrafine grained. To simulate the thermal distribution during laser treatment, finite element method simulations were made for different laser energy densities. During laser treatment oil reserving holes were formed due to the inhomogenity of the pearlitic matrix and graphite lamellae, and the high temperature of the laser treatment. To quantify the number of oil reserving holes, a new image analysis method has been developed. It was found that the amount of oil reserving holes increased with higher laser energy densities.Keywords: high temperature treatment, laser surface treatment, cast iron, cylinder bore, finite element method, focused ion beam, image analysis

The air pollution emission standards for automobiles are going to be more strict worldwide. European automotive manufacturer makes a laser treatment on the cast iron cylinder bores of the V-engine blocks. Samples of laser treated cast iron cylinder bore with lamellar graphite were investigated. Seven samples were treated with XeCl-excimerlaser, Nd-YAG laser and Yb-fiber laser sources. In order to evaluate the microstructure and grain size of the laser treated layer, scanning electron microscopic (SEM) images were taken in cross section with a SEM/focused ion beam (FIB) dual beam electron microscopes. All the samples were found to be ultra fine grained. To simulate the heating conditions during laser treatment, finite element method (FEM) simulations were made for the different lasertypes. Additional X-ray diffraction measurements showed retained austenite after laser treatment.