Key Engineering Materials Vol. 662

Abstract: The aim of this work was to analyze changes in local toughness KCV using Charpy V-notch impact tests in the slab surface zone in relation to the microstructure in ULC/ IF steel and TiNb HSLA steel. Marked heterogeneity in KCV values was confirmed in the surface zone across the width of transitional slabs. Distinct local differences in notch toughness across the slab width were found to be linked primarily with changes in ferrite grain size. Low KCV values in the analyzed steels were linked with coarse grain structure, while much finer ferrite structure was identified in tough samples. The heterogeneity of KCV vales in the analyzed steels may be influenced by differences in thickness of the fine-grain slab surface zone, and by the presence of tertial cementite and (in HSLA steel) of pearlite as well.

Abstract: This paper deals with the non-destructive evaluation of surface made of hardened roll bearing steel after hard milling via Barkhausen noise technique. The paper discusses magnetic anisotropy linked with the structure transformations with regard to variable flank wear of cutting tool. Effective value of Barkhausen noise (BN) and Peak Position derived from the raw BN signal as well as BN envelopes are compared with metallographic observations and theoretical background about magnetic domains reconfiguration when the near surface undergoes severe plastic deformation at elevated temperatures.

Abstract: This work deals with the strain at the core-shell interface of Fe nanoparticles. Series of Fe nanoparticles with various mean diameters were prepared by precipitation in solid state in binary Cu-Fe alloy. Further, nanoparticles were isolated by dissolution of Cu matrix. High-energy X-ray diffraction (XRD) was used to probe structure of nanoparticles. XRD measurements suggest presence of the core-shell structure, where core and shell of the nanoparticles are formed of α-Fe and CuFe₂O₄ phase, respectively. Strains in core and shell were estimated as a function of nanoparticles size by Williamson-Hall method.

Abstract: We analyzed the failure characteristics of the metallic glass Co₄₃Fe₂₀Ta_5.5B_31.5 (at.%) deformed in bending. The nanoscale fracture surface morphology respects the micromechanisms of the failure of the amorphous structure. The fracture surfaces consist of nanosized dimples (40 nm) arranged in the lines respecting the periodic corrugation zones oriented perpendicular to the crack propagation direction. The corrugation topology exhibits the point nature of the generation site, the concentric form of the stress waves and their interference.

Abstract: Every manufacture of any plastic parts produces some waste, such as defective injects or cold runner system from injection molding technology. This waste can be directly used several times. But when size of this material is reduced, particles of different sizes are made. From large particles similar to the original granulate material, to dust particles. This size variation can cause problems during subsequent processing. These particles of different size have distinct melting rate. That can cause an inhomogeneity of a melt and diverse structure of solidified polymer. This research paper studies the influence of the particle size of recycled polymeric material on the micro harness properties of semi-crystalline polyamide 6 at room temperature.

Abstract: This paper examines the mechanical properties of the composite of thermoplastic polymer matrix with carbon nanotubes. As the basic polymer matrix polyamide (PA) was used to which the nanoparticles in a given percentage by weight in the form of nanotubes were added. Composite was injected into the Arburg injection molding machine. Different mechanical properties were measured for evaluation. These tests are compared with polymeric materials without added nanofiller. In conclusion influence on the mechanical properties of polymer matrix with carbon nanotubes and without fillers is evaluated.

Abstract: The main goal of this paper is to compare measurements of creep behavior of Crosslinking polymer materials. Creep properties have been measured by two methods, first is micro-indentation with Depth Sensing Indention (DSI) and the second method is long-term creep test in room temperature. By using of these principally different methods can be better analyzed the influence of radiation netting, and therefore better suggest an appropriate dose of radiation with respect to use of polymer material in practice. The evaluation criteria for DSI test is index CIT [%]. The evaluation criteria for the standard creep test is value of average elongation at the end of the test. Comparison of these two values shows slight influence of radiation dose with using the standard creep test instead of using micro-indentation creep test, which shows very slight influence of radiation dose on material.

Abstract: The applied squeeze casting technique makes possible the local strengthening with ceramic fibers or ceramic particles of elements with Al-alloy matrices. In this paper the elaborated technology of manufacturing of porous ceramic preforms from Saffil fibers is shown and technology of squeeze casting elaborated at Wrocław University of Technology, Chair Foundry, Polymers and Automation described. There were applied the preforms characterized by porosities of 90% and 80%, what after squeeze casting with liquid EN AC - 44200 Al alloy produces the composite materials containing 10 vol. and 20 vol.% of fiber strengthening. The structural phenomena at the interface of strengthened alloy investigated with the optical and electron microscopy are discussed and the mechanical properties of manufactured composite materials are shown.

Abstract: An intensive research in load-bearing glass structures leads to the requirement for performing glass-to-glass or glass-to-different material connections. Glued shear connection is suitable for these applications mainly due to its uniform stress distribution in larger area in comparison with bolted connections. The reliability of adhesive in the connection during the life time of a structure is affected by many factors, [1], [2], [3], [4]. The article deals with the experimental analysis focused on the determination of material characteristics of adhesives in planar connections, it describes the effect of various factors on the behavior of an adhesive joint under increasing shear loads, its ultimate load-bearing capacity and its failure modes. The main investigated factors are the type of adhesive, the type of connected materials (material of substrate), surface treatment and the thickness of the adhesive layer. Due to importance of adhesive layer thickness especially in rigid and semi-rigid glues, numerical models responding to the effect of thickness was carried out.

Abstract: Properties of laminated glass comprising two or more sheets of glass are greatly affected by the composite action of these panes which is influenced by material properties of used interlayer. Generally plastic foil or cast resin is used as the interlayer in lamination process. Laminated glass has been experimentally investigated in the laboratory condition in a four-point bending test on several kinds of interlayers in combination with variable thickness of the annealed glass. This paper establishes the so-called effective bending thickness according to standard method and presents comparisons with experimentally determined values.