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Application of Additive Manufacturing for the Repair of Forging Dies

Abstract

In this paper the investigated conditions and possibilities of repairing forging dies with high precision robotic MAG welding are presented. Different welding wire electrodes were examined and compared by their processability. Productivity, process stability, slag and fume formation were in the focus of investigation. Metallographic tests were carried out to validate the compliance of welded layers. Based on the performance of the wire electrodes, recommendations have been elaborated for the procedure specification and also for further investigation. Some robot cell layouts have been designed adapting to the special working environment and requirements of the welding procedure.

Open access
Development of a Composite Material for Impact Load

Abstract

The goal of this work was to invent a high energy absorbing composite material. This composite needs to be able to attach on the building's surfaces and increase blast-resistance. In this innovation, the test samples were reinforced with aramidfiber, glass fiber and carbon fiber and tested by Charpy pendulum impact testing machine. During the tests, the aramid and glass fiber reinforced composites showed good resistance and high energy absorption against impact load.

Open access
Dynamic and High Temperature Quasi-static Examination of Tempered Glass

Abstract

In everyday use glass materials cause a lot of damage or injuries when broken, as fracture mechanism and damage runoff cannot be predicted precisely. To gain knowledge on this issue, we studied the properties of tempered glass. The glass test samples were exposed to two types of destructive evaluations: normal and high temperature three-point bending and room temperature dynamic experiments with colliding small steel spheres. The evaluation showed that high temperature experiments are in correlation with sharp fracture edges, and dynamic impact creates shell featured circular crack propagation which prevents the spreading of the radial cracks, so the damage is concentrated to a small area.

Open access
Examination of Drug-eluting Coatings of Coronary Artery Stents

Abstract

Drug-eluting stents provide a solution for treating restenosis in arteries expanded by using conventional bare metal stents, but there are a small number of publications on the processes of coating damage established due to the various effects that occur during the life cycle of the stent. In the current research damage to the coating was investigated along with the effects of damage on the corrosion resistance of the stent in multiple ways. This research investigates not only traditional drug eluting stents with polymer matrix, but also the new generation of polymer-free types.

Open access
Examination of Heat Treatment on the Microstructure and Wear of Tool Steels

Abstract

The microstructure of the investigated X153CrMoV12 grade tool steel in delivered condition consisted of spheroidal matrix and primary carbides. The primary carbides were not dissolved under austenitisation time on either 1030°C or 1070°C. The microstructure and abrasion resistance of the steel changed due to quenching from different austenitisation temperatures. After conventional quenching from the higher austenitising temperature, there is more residual austenite in the steel than at quenching from the lower austenitisation temperature, which decreased the wear resistance. As a result of quenching from 1070°C followed by a multiple tempering process around 500 to 540°C, the retained austenite content is reduced and finely dispersed carbides are precipitated in the matrix, resulting in a higher matrix hardness and an increased wear resistance. After cryogenic treatment, the residual austenite content decreases compared to the conventional process, which leads to an increase in hardness and wear resistance.

Open access
Investigation of Milling of Carbon Fiber Reinforced Plastic

Abstract

The use of fiber-reinforced plastics has increased significantly in the past decades. Consequently, the demand for finishing and machining of such materials has also escalated. During machining, the fiber-reinforced materials exhibit machining problems dissimilar to the problems of metals. These are fiber pull-out, fiber breakage in the cutting zone, matrix smearing and delamination. The purpose of this experiment is to investigate the characteristics of the resultant force (Fe) dur-ing the milling of carbon fiber reinforced plastic as a function of input machining parameters. For the force measurements, CFR with perpendicular (0°-90°) fiber orientation was machined. The experimental design involved the central composite design method. To analyze and evaluate the measurements, we applied the response surface methodology.

Open access
Laser Cutting of Austenitic Corrosion-Resisting Steels

Abstract

Cutting of thick austenitic stainless steel sheets with a disc laser is not fully developed. In this research were investigated the surface of holes made on 3.25 mm thick stainless-steel cut with CO2 laser beam and disk laser beam. Using optical microscope and electron microscope to examine the cutting surfaces, were observed that the cutting with the CO2 laser result high quality surface (cutting 3,25 mm thick plates), but holes made with solid-state laser has microcracks on the inner side. These cracks are not acceptable to the customers.

Open access
Microstructural Characterisation of Archeologic Finds Discovered at the Ironworks in Mădăraș

Abstract

In the middle of the 16th century the ironworks of Mădăraș was one of the important centres of iron production. During its one and a half century lifespan its output provided a significant part of Transylvania’s iron supply. While it operated it used up the entire raw material extracted in the iron ore mines of the Felcsík basin. This study presents the reconstructed ground-plan of the ironworks, its layout on the shores of the Mădăraș creek, and the chemical composition and microstructure of the samples discovered during exploration of the location by means of XRF analysis, EDS analysis and metallography. The analysis of the pig iron, the steel and the slag although performed on individual samples, still provides a good approach regarding the products of the ironworks, their chemical composition and microstructural characteristics.

Open access
Roaming of Materials Scientists in Biology: Structural Colours of Butterfly Wings

Abstract

The photonic nanoarchitectures occurring in the wing scales of Lycaenid butterflies were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and UV-VIS spectroscopy. We found that the males of all the nine investigated species possess photonic nanoarchitectures built according to the same general “plan”, but each species exhibits species-specific features which results in species-specific colours reproduced generation by generation with a high degree of accuracy.

Open access
Role of the Features of Focused Laser Beam at Pulsed Laser Cutting

Abstract

In this article investigation of the roles of two important factors of focused laser beam, the focal spot diameter and the Rayleigh length as determining variables of the beam quality were made. The equations of these two factors are based on those most commonly used in the literature. The exchange between three different beam quality numbers were shown. It is proven on the basis of the scientific literature, that the beam quality degrades compared to the original data given by the factory of laser. The causes of the beam quality degradation are lens aberrations in the optical path of the given laser, and the shifting of the beam propagation ratio (M2) to higher values. A new equation for estimation of the new, lowest value for M2 factor is presented, based on the comparison of the laser cut material thickness to the depth of focus, which is two times the Rayleigh length.

Open access