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Microstructural characterization of laser cladded AISI 316 stainless steel on a carbon steel substrate

Authors: Tomaž Irgolič, David Potočnik, Mirko Ficko, Peter Kirbiš,

Abstract

Laser engineering net shaping (LENS) is a method of depositing metals into fully shaped parts or for the production of clad layers of noble or wear resistant metals on construction grade steels. In the current work stainless steel was deposited using different combinations of processing parameters such as speed, layer thickness and laser power. The resulting microstructures within the clad layers were then characterized using different etching techniques. Microstructures formed during the SLM process are comprised of columnar grains with a cellular, cellular/dendritic substructure. The exact shape of these grains is difficult to observe with the use of common etching techniques, this is especially true when considering thin cladded layers, with dissimilar etching behavior. For this purpose we compared a variety of different etchants, which attack the ferrite phase or produce a tint effect. Special attention was giving to the delineation of the columnar grains, which under certain processing parameters can exceed the thickness of individual deposited layers.

Key words: LENS; stainless steel; microstructural characterization; tint etching; solidification microstructure

DOI: 10.24867/ATM-2019-2-001

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Ballistic behavior of multilayer wire mesh application armor

Authors: Sebastian Baloš, Milan Pećanac, Mirjana Trivković, Leposava Šidjanin

Abstract

In this paper, an attempt was made to increase the ballistic protection of the armor system by combining non-homogenous spaced armor in form of multilayer wire mesh with rolled homogenous armor steel base plate. Different angles of incidence were tested: 0, 20, 25 and 35o, by using 12.7 mm armor piercing incendiary ammunition from 100 m. It was found that the inclination of the armor system has a negative effect on ballistic resistance due to variations in wire body-to-body distance, some of which can increase, causing a decreased contact with the projectile and an insufficient yaw. The yaw causes a sideways impact on the base plate. However, the non-penetrating hits in vertical armor cause a more severe damage on the base plate compared to the inclined armor system. This effect is due to the inclination itself, which is a common behavior of increasing effectiveness of sloped armor.

Key words: ballistic testing; wire mesh; spaced armor

DOI: 10.24867/ATM-2019-2-002

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Distinctiveness of Welding Joints Design Based on Mechanical and Corrosion Environmental Influence on Low Carbon Steel

Authors: Oladele I. O,Alonge D. B, Betiku O. T, Barnabas A. A and Shittu S.

Abstract

Experimental investigations were carried out to study the effect of weld joint designs and post weld heat treatment (PWHT) on mechanical and corrosion properties of low carbon steel. Butt, bevel and half-lap joints were produced with a voltage of 20 V and current of 110 A with the use of 3.2 mm diameter electrode E6013. Full annealing was carried out on part of the welded samples in order to consider the possibility of post weld heat treatment for better performance. The mechanical properties (tensile, hardness, and impact toughness) were studied for both the as welded (AW) and PWHT samples as well as the corrosion performance in a natural sea water environment containing 3.5 wt.% NaCl using potentiodynamic polarization method. The microstructure of the AW and PWHT samples of the welded joints with the most promising mechanical and corrosion properties were then characterized by means of an optical microscopy. The results obtained reveals that the bevel joint followed by half lap joint and the butt joint of the as weld samples gave the best combination of the mechanical properties considered. On the other hand, the corrosion properties of the butt joint were superior to that of the bevel and half lap joint, respectively in the PWHT condition as compared to the AW samples. This implies that PWHT improves the corrosion resistance of the welded steel joints.

Key words: low carbon steel; optimum welding parameters; weld joint design; post weld heat treatment.

DOI: 10.24867/ATM-2019-2-003

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The Optimization of Thermoforming Process Parameters in the Packaging of Medical Products

Authors:Edina Karabegović, Redžo Đuzelić

Abstract

The use of plastics has a very important role in the packaging of medical products. The choice of material and packaging process is important for the sustainability of the medical product quality, which has a direct impact on the user health. For the purpose of protection, depending on the type of medical product or the degree of risk to human health, the medical product packaging process is given a particular importance. Standard methods have been defined for performing the packaging process. In order to achieve the satisfactory quality of the packaging, and following the experimental analysis of the influence of thermoforming process parameters on the packaging design, the paper provides their optimum values. Minitab software was used for the analysis and optimization of the parameters.

Key words: medical packaging, thermoforming, parameters, optimization.

DOI: 10.24867/ATM-2019-2-004

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Challenges in Experimental Evaluation of Morphological, ChemoMechanical and Adhesive Properties of Glass-ionomer Based Dental Materials

Authors: Bojan Petrović, Evgenija Marković, Tamara Perić, Sanja Kojić,

Abstract

Changes in composition and new material characteristics require verification in clinical and experimental studies. Investigating glass-ionomer cements under laboratory conditions encounters problems in interpreting the results and in comparing them with other types of materials tested in the same way. As the connection between the glass-ionomer cements and the dental tissues is delicate, it is often the case that the impact of fractures and other artifacts is either underestimated or over-dimensioned when interpreting the results. A critical review was performed, with defining the main problems regarding the usage of SEM, EDX and nanoindentation techniques in glassionomer based materials evaluation.

Key words: glass-ionomer, SEM, EDX; nanoindentation, surface characterization

DOI: 10.24867/ATM-2019-2-005

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