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This paper describes a study of explosively welded titanium-carbon steel S355J2+N plates. Following the welding, plates underwent heat treatment at temperature of 600°C for 90 min with cooling in furnace to 300°C and in air to room temperature. The structure of the bonding was examined by using light, scanning electron (SEM) and transmission electron microscopy. The mechanical properties before and after heat treatment were examined applying three-point bending tests with cyclic loads and hardness measurements. Fracture surfaces were investigated using computer tomography and SEM. It has been found that the bonding areas are characterized by a specific chemical composition, microstructure and microhardness. Between the steel and the Ti cladding, a strongly defected transition zone was formed and melted areas with altered chemical composition were observed. It was also demonstrated that the heat treatment commonly applied to welded steel-Ti plates had a significant and negative impact on the microstructure and mechanical properties of the welded plates due to formation of brittle intermetallic phases.

The aim of this research was to investigate the influence of post-weld heat treatment (PWHT, precipitation hardening) on the microstructure and fatigue properties of an AA2519 joint obtained in a friction stir-welding process. The welding process was performed with three sets of parameters. One part of the obtained joints was investigated in the as-welded state and the second part of joints was subjected to the post-weld heat treatment (precipitation hardening) and then investigated. In order to establish the influence of the heat treatment on the microstructure of obtained joints both light and scanning electron microscopy observations were performed. Additionally, microhardness analysis for each sample was carried out. Fatigue properties of the samples in the as-welded state and the samples after post-weld heat treatment were established in a low-cycle fatigue test with constant true strain amplitude equal to ε = 0.25% and cycle asymmetry coefficient R = 0.1. Hysteresis loops together with changes of stress and plastic strain versus number of cycles are presented in this paper. The fatigue fracture in tested samples was analyzed with the use of scanning electron microscope. Our results show that post-weld heat treatment of AA2519 friction stir-welded joints significantly decreases their fatigue life.

The medium size divertor tokamak ASDEX Upgrade (major and minor radii 1.65 m and 0.5 m, respectively, magnetic-field strength 2.5 T) possesses flexible shaping and versatile heating and current drive systems. Recently the technical capabilities were extended by increasing the electron cyclotron resonance heating (ECRH) power, by installing 2 × 8 internal magnetic perturbation coils, and by improving the ion cyclotron range of frequency compatibility with the tungsten wall. With the perturbation coils, reliable suppression of large type-I edge localized modes (ELMs) could be demonstrated in a wide operational window, which opens up above a critical plasma pedestal density. The pellet fuelling efficiency was observed to increase which gives access to H-mode discharges with peaked density profiles at line densities clearly exceeding the empirical Greenwald limit. Owing to the increased ECRH power of 4 MW, H-mode discharges could be studied in regimes with dominant electron heating and low plasma rotation velocities, i.e. under conditions particularly relevant for ITER. The ion-pressure gradient and the neoclassical radial electric field emerge as key parameters for the transition. Using the total simultaneously available heating power of 23 MW, high performance discharges have been carried out where feed-back controlled radiative cooling in the core and the divertor allowed the divertor peak power loads to be maintained below 5 MW m−2. Under attached divertor conditions, a multi-device scaling expression for the power-decay length was obtained which is independent of major radius and decreases with magnetic field resulting in a decay length of 1 mm for ITER. At higher densities and under partially detached conditions, however, a broadening of the decay length is observed. In discharges with density ramps up to the density limit, the divertor plasma shows a complex behaviour with a localized high-density region in the inner divertor before the outer divertor detaches. Turbulent transport is studied in the core and the scrape-off layer (SOL). Discharges over a wide parameter range exhibit a close link between core momentum and density transport. Consistent with gyro-kinetic calculations, the density gradient at half plasma radius determines the momentum transport through residual stress and thus the central toroidal rotation. In the SOL a close comparison of probe data with a gyro-fluid code showed excellent agreement and points to the dominance of drift waves. Intermittent structures from ELMs and from turbulence are shown to have high ion temperatures even at large distances outside the separatrix.

This investigation presents the results of research on low cycle fatigue properties of Sc-modified AA2519-T62 extrusion. The basic mechanical properties of the investigated alloy have been established in the tensile test. The low cycle fatigue testing has been performed on five different levels of total strain amplitude: 0.4%; 0.5%; 0.6%; 0.7% and 0.8% with cycle asymmetry coefficient R = 0.1. For each level of total strain amplitude, the graphs of variations in stress amplitude and plastic strain amplitude in the number of cycles have been presented. The obtained results allowed to establish Ramberg-Osgood and Manson-Coffin-Basquin relationships. The established values of the cyclic strength coefficient and cyclic strain hardening exponent equal to k’ = 1518.1 MPa and n’ = 0.1702. Based on the Manscon-Coffin-Basquin equation, the values of the following parameters have been established: the fatigue strength coefficient σ’f = 1489.8 MPa, the fatigue strength exponent b = −0.157, the fatigue ductility coefficient ε’f = 0.4931 and the fatigue ductility exponent c = −1.01. The fatigue surfaces of samples tested on 0.4%, 0.6% and 0.8% of total strain amplitude have been subjected to scanning electron microscopy observations. The scanning electron microscopy observations of the fatigue surfaces revealed the presence of cracks in striations in the surrounding area with a high concentration of precipitates. It has been observed that larger Al2Cu precipitates exhibit a higher tendency to fracture than smaller precipitates having a higher concentration of scandium and zirconium.

The progressive increase in the amount of glass waste produced each year in the world made it necessary to start the search for new recycling methods. This work summarizes the experimental results of the study on mortar samples containing dispersed reinforcement in the form of glass fibers, fully made from melted glass waste (bottles). Mortar mixes were prepared according to a new, laboratory-calculated recipe containing glass fibers, granite as aggregate, polycarboxylate-based deflocculant and Portland cement (52.5 MPa). This experimental work involved three different contents (600, 1200, and 1800 g/m3) of recycled glass fibers. After 28 days, the mechanical properties such as compressive, flexural, and split tensile strength were characterized. Furthermore, the modulus of elasticity and Poisson coefficient were determined. The initial and final setting times, porosity, and pH of the blends were measured. Images of optical microscopy (OM) were taken. The addition of glass fibers improves the properties of mortar. The highest values of mechanical properties were obtained for concrete with the addition of 1800 g/m3 of glass fibers (31.5% increase in compressive strength, 29.9% increase in flexural strength, and 97.6% increase in split tensile strength compared to base sample).

The paper describes an investigation of an explosively welded Mg/Al/Ti multilayer composite. Following the welding, the composite was subjected to hot-rolling in three different temperatures: 300 °C, 350 °C and 400 °C, with a total relative strain of 30%. The rolling speed was 0.2 m/s. The investigation of the composite properties involves microhardness analysis and mini-specimen tensile tests of the joints. The composite Mg/Al and Al/Ti bonds in the as-welded state and after rolling in 400 °C were subjected to microstructure analysis using scanning electron (SEM) and transmission electron microscopy (TEM). In the Al/Ti interface, the presence of melted zones with localized intermetallic precipitates has been reported in the as-welded state, and it has been stated that hot-rolling results in precipitation of intermetallic particles from the melted zone. The application of the hot-rolling process causes the formation of a continuous layer in the Mg/Al joint, consisting of two intermetallic phases, Mg2Al3 (β) and Mg17Al12 (γ).

The aim of this research was to investigate the effect of friction stir welding (FSW) parameters on microstructure and mechanical properties of Sc-modified AA2519 extrusion joints. The workpiece was welded by FSW in non-heat-treated condition with seven different sets of welding parameters. For each obtained joint macrostructure and microstructure observations were performed. Mechanical properties of joints were investigated using tensile test together with localization of fracture location. Joint efficiencies were established by comparing measured joints tensile strength to the value for base material. The obtained results show that investigated FSW joints of Sc-modified AA2519 in the non-heat-treated condition have joint efficiency within the range 87–95%. In the joints obtained with the lowest ratio of the tool rotation speed to the tool traverse speed, the occurrence of imperfections (voids) localized in the stir zone was reported. Three selected samples were subjected to further investigations consisting microhardness distribution and scanning electron microscopy fractography analysis. As the result of dynamic recrystallization, the microhardness of the base material value of 86 HV0.1 increased to about 110–125 HV0.1 in the stir zone depending on the used welding parameters. Due to lack of the strengthening phase and low strain hardening of used alloy the lack of a significantly softened zone was reported by both microhardness analysis and investigation of the fractured samples.