Materials Science Forum Vol. 812

Abstract: A fully automated laboratory-scale workstation has been constructed for simulating industrial acid pickling processes of steel sheet products. The device built comprises 4 liquid tanks that can be heated up to 80 °C and an arbitrary immersion program can be performed with the sheets to be tested by varying the immersion time and the motion velocity in each tank. The weight loss has been measured for both hot-rolled and cold-rolled specimens as a function of all variable parameters. The weight loss associated with the removal of the oxide layer could be established. The average oxide-related loss was 58 g⋅m^-2 and 2 g⋅m^-2 for hot-rolled and cold-rolled samples, respectively. It was found that the immersion time is the decisive parameter in the weigh loss measured, while the motion velocity and the temperature of the sample treatment are of secondary importance.

Abstract: The magnitude of different aluminium alloys, especially the ones with higher strength, are increasing in the structural engineering, not just the usual applications (like the aerospace industry) but more likely in the automotive industry. There are more assumptions of the effective use of aluminium; we should highlight two important factors, the technological and the applicability criterions. The technological criterion is the joining of structural elements, frequently with welding thus the technological criterion ultimately is the weldability. The assumption of applicability comes from the loading capability of these structures, which is typically cyclic loading so the key issue from the point of view of applicability is the resistance to fatigue. This article represents physical simulation and fatigue test results both on the base material and on the welded joints.

Abstract: Devices used in the field of medical technology require high biocompatibility. Medical devices that are made from stainless steel have good biocompatible properties, but polymer coatings can radically improve it. One of the most important quality of the coating is adhesion, and this was our rationale for developing a polymer adhesion testing protocol. In our research, two biocompatible polymers were compared, polyurethane (PUR) and poly-(DL-lactic-co-glycolic acid) (PDLG). Surface-treated stainless steel sheets were used as carrier for polymer layers. The adhesive properties of different layers were compared. Adhesion of the coatings was characterised by concentration of coating solution and surface roughness of the carriers, and some phenomena were observed.

Abstract: In this study the typical bonding faults of three layer-plated aluminum sheets are investigated. The bonding was performed between AlMn1Si0.8 and AlSi10 alloys using hot rolling (a VON ROLL experimental duo mill). The experimental temperatures were 460, 480 and 500 °C. T-peel test provided a good description about the quality of bonding. Structure analysis was also performed by light microscopy to detect typical bonding faults. The aim of this investigation is to produce some typical bonding faults and find the cause of formation. The influence of the rolling temperature and surface roughness on the bonding was also analyzed. Rolling schedule and the role of first pass on the development of perfect bonding were experimentally determined.

Abstract: In the course of our investigations, AlSi8Cu3 foundry alloy was alloyed in different strontium and antimony concentrations. The mechanical properties of structure developed during the given cooling conditions as well as the effect of strontium and antimony on the modification of eutectic Si were investigated by a computer image analysis and by using a scanning electron microscope. Samples with a wall-thickness of 8 mm cast in the course of the experiment-series were used for our investigations. A part of our long-term research work is described in our present paper.

Abstract: Nowadays forensic sciences try to keep up with criminality. Unfortunately despite this criminality continues to grow. Armed robbery, murder have become rife, yet the number of other crimes does not seem to decrease.

Abstract: High energy explosions and irradiation may cause that the minerals and mineraloids form glassy phase on the earth surface. We would like to determine the mechanical properties of these glassy materials. To achieve this and manufacture samples we need to measure the main technological property, the viscosity.

Abstract: Gradient materials get more and more importance in both material science and numerical studies of technological processes. Their mathematical model is called the constitutive equation. The theoretical background of such model is presented on the basis of thermodynamics and continuum mechanics. The results show which is the quantity to measure to get constitutive equation for gradient dependent materials.

Abstract: The estimation of thermal boundary conditions occurring during heat treatment processes is an essential requirement for characterization of heat transfer phenomena. In this work, the performance of five optimization techniques is studied. These models are the Conjugate Gradient Method, the Levenberg-Marquardt Method, the Simplex method, the NSGA II algorithm and a hybrid approach based on the NSGA II and Levenberg-Marquardt Method sequence. The models are used to estimate the heat transfer coefficient in 2D axis symmetrical case during transient heat transfer. The performance of the optimization methods is demonstrated using numerical experiments.

Abstract: As particle filled and fiber reinforced polymer matrix composites are frequently used in many demanding industrial applications, the proper prediction of the deformation behavior of these materials is of high practical importance for a reliable product design. To predict the thermo-mechanical behavior, micromechanics based simulations were performed using both the mean field homogenization methods (MFH) and full-scale finite element (FS-FE simulations on a material specific representative volume. The applicability and limitations of both methods are introduced based on five different practical examples. Both thermoplastic polymers and elastomers were used as matrix materials with combination of fillers made from different materials having different aspect ratio and revealing a wide variation of alignments and arrangements. While conventionally the behavior of composites revealing processing induced microstructure is predicted for practical engineering applications, novel artificial micro-structures revealing special functionalities might also be designed and their behavior predicted for supporting material development efforts.