Welding Institute (Slovenia)

Roman Ovilava (Wels), based on research results of the past 20 years] Recent archaeological digs in the Roman part of Wels have yielded evidence of a high standard of living, both in the centre and on the outskirts of the settlement, as well as remains of baths to the north.Alongside the known course of the city wall around the approximately 90 ha settlement, an inner road was also identified at several points.Just inside the fortification, a wide ditch has been discovered in some areas, which probably forms part of an earlier defence system.Construction works near a necropolis east of the city unveiled numerous cremation and inhumation burials dating from the 2nd and 3rd centuries AD.In addition, Baiuvarii graves were found near the ancient grave road.About three Roman miles north of Ovilava, remains of a villa rustica in use until the 4th century AD have been found.Further west, burial groups forming part of as yet unknown estates have been uncovered.

The thermal and deformation cycle during welding is directly reflected on the formation of the welded joint and the imperfections that can occur in any specific case. The simulation modelling of the heating and cooling processes makes it possible to determine the temporary and residual stresses in the welded joint. When solving the thermal and deformation tasks, it is essential to use data on the characteristics of the material in the entire temperature range in which the studied processes take place. At the same time, these data are often not available. In order to be able to use simulation solutions in practice, the standard EN ISO 18166 provides for calibration of thermal and deformation models before they are applied to the welded structure. In this study, the calibration of a thermal model applicable to MIG / MAG welding is considered. The heat source is superficial and axisymmetric. The calibration parameters are efficiency, effective radius of the heat source and coefficient determining the deviation from the normal central Gaussian distribution. Experimental data on the bead shape were used for the calibration process. The obtained simulation results for the temperature field are compared with the experimental ones. Sensitivity analysis of the solution with respect to the material characteristics was performed.

Due to the increasing demand for connecting cells in packets to power electric tools, bicycles and electric cars, the issue of the quality of battery cells with busbars joints with the use of external heat electrodes is particularly important. The paper presents the conditions of the joining process and modelling results using the DC source. Modelling was performed using commercially available Sorpas 3D software. It included checking the influence of the busbar shape, clamping force, electrode material, the shape of electrode face, the length of the tungsten inserts in the welding electrodes on the amount of heat and the diameter of the connections. Modelling results revealed in particular increased heat generation and connection diameters for electrodes with a smaller work surface, however, industrial practice shows that the electrode face diameter durability is limited and that the electrodes flatten - the electrode face diameter increases.

Abstract Nickel-based alloys are widely used in industries such as the aircraft industry, chemicals, power generation, and others. Their stable mechanical properties in combination with high resistance to aggressive environments at high temperatures make these materials suitable for the production of components of devices and machines intended for operation in extremely difficult conditions, e.g. in aircraft engines. This paper presents the results of thermal and mechanical tests performed on precision castings made of the Inconel 713C alloy and intended for use in the production of low pressure turbine blades. The tests enabled the determination of the nil strength temperature (NST), the nil ductility temperature (NDT), and the ductility recovery temperature (DRT) of the material tested. Based on the values obtained, the high temperature brittleness range (HTBR) and the hot cracking resistance index were determined. Metallographic examinations were conducted in order to describe the cracking mechanisms. It was found that the main cracking mechanism was the partial melting of grains and subsequently the rupture of a thin liquid film along crystal boundaries as a result of deformation during crystallisation. Another cracking mechanism identified was the DDC (Ductility Dip Cracking) mechanism. The results obtained provide a basis for improving precision casting processes for aircraft components and constitute guidelines for designers, engineers, and casting technologists.

Summary The influence of cutting technologies on the quality, mechanical properties and microstructure of the cut edges of steel is presented. The cutting technologies cover: plasma, laser beam, water jet and oxyfuel flame cutting. During investigation the measurements of perpendicularity tolerance, hardness, mean high of the profile Rz5 and metallographic examination were carry out. The results revealed that the lowest hardness was achieved by water jet cutting, whereas the highest was obtained by plasma cutting under the water surface. The lowest perpendicularity was obtained by plasma cutting under the water surface but the highest was achieved by laser and HD plasma cutting. The conducted experiments revealed moreover that the lowest roughness was achieved by means of plasma cutting over the water surface, whereas the highest by laser beam cutting.

The Ultrasonic Peening (UP) is the most efficient technique for increasing the fatigue life of welded elements as compared to such existing improvement treatments as grinding, TIG-dressing, shot peening, hammer peening, etc. The results of experimental investigation of the efficiency of UP for rehabilitation and repair of welded elements and structures with the goal of preventing the origination and propagation of fatigue cracks are considered in this document. UP treatment was applied to large-scale welded specimens in as-welded condition, after 50 % of expected fatigue life and after repair of fatigue cracks. Also, different techniques for restraining and repair of fatigue cracks were analyzed and compared: overloading; drilling of the crack tips; drilling of the crack tips with installation of high strength bolts; local explosive treatment; local heat treatment; welding with and without UP of weld toe zones. As an example, the practical application of UP for rehabilitation and repair of welded elements of highway and railway bridges are also discussed.

The structure of a novel cyclic peptide (1) produced by Actinomycete sp. has been assigned on the basis of extensive NMR and mass spectral data.

The present paper considers algorithmic optimisation of autogenous manual tungsten inert gas (TIG) welding of four different types of joint using stainless steel sheet of varying thickness from 0.9 to 2.0 mm. First a literature survey is presented, experimental work and the equipment used are described, welding conditions are stated, and the welded joints are represented. Then, experimental results are analysed, assessed, and presented in tables and graphs. Mathematical modelling for the calculation of maximum, minimum, and optimum values of welding current and welding voltage as functions of sheet thickness is described for the four joints. Finally, algorithmic optimisation is described for a particular case, namely, a T joint with a fillet weld. The entire algorithm for optimisation of TIG welding is represented.