Tomaž VuhererUniversity of Maribor | UM · Laboratory for Welding
Tomaž Vuherer
PhD, IWE, IWI-c
About
144
Publications
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Introduction
Tomaž Vuherer currently works at the Laboratory for Welding, University of Maribor. Tomaž does research in Industrial Engineering, Materials Engineering and Mechanical Engineering. Their current project is 'TIG and Plasma Arc Welding of High Alloy Cr-Ni Austenitic Steels and Pearlitic Steels by Using Activating Fluxes'.
Additional affiliations
January 2010 - May 2017
Publications
Publications (144)
This article contains an advanced analysis of the properties of solid wire electrical contacts produced by ultrasonic welding, both with and without varnish. The main disadvantage of ultrasonic welding of thin wires is the inability to achieve acceptable peel force and tensile strength, which is mainly due to the deformation and thinning of the wir...
A complementary characterisation of the Al-alloy EN AW-5454 was carried out, intended for obtaining the laser hybrid welding parameters of subassemblies in the automotive industry. The investigation included a microstructural examination and the determination of the alloy’s properties using several analytical methods (HV5 hardness measurement, tens...
Despite recent advancements, the wear of conveyor systems in bulk
material handling remains a significant challenge. Addressing this issue
requires enhanced efficiency and reduced maintenance costs. Hard
welding, a process where a wear-resistant material is deposited onto a
softer substrate, is frequently utilized to improve wear resistance,
partic...
A complementary characterisation of the Al-alloy EN AW-5454 was carried out, intended for obtaining the laser hybrid welding parameters of sub-assemblies in the automotive industry. The investigation included a microstructural examination, and determination of the alloy's properties using several analytical methods (HV5 hardness measurement, tensil...
The aim of this work is to study joining Al 2024-T3 alloy plates with different welding procedures. Aluminum alloy AA 2024-T351 is especially used in the aerospace industry. Aluminum plates are welded by the TIG and MIG fusion welding process, as well as by the solid-state welding process, friction stir welding (FSW), which has recently become very...
Cladding with a stick electrode is one of the oldest arc processes for adding a deposit on a base material. The process is suitable for outdoor working, but the disadvantages are low productivity and large dilution rates. In this work, a simple solution is proposed, which would enable cladding of a larger area with one pass and decrease the dilutio...
The production of personal protective equipment (PPE) has increased dramatically in recent years, not only because of the pandemic, but also because of stricter legislation in the field of Employee Protection. The increasing use of PPE, including disposable surgical masks (DSMs), is putting additional pressure on waste collectors. For this reason,...
The application of conventional electric arc welding in argon protection (TIG welding process) has limited possibilities. These limitations are primarily related to the thickness of the welded material and the need to prepare the groove for their welding. Overcoming these limitations in TIG welding was done by using activating flux, so the procedur...
This paper aims to present the effects of the MIG welding on the mechanical properties of a buttwelded joint of dissimilar aluminium alloys 2024-T351 and AA 6082-T6. Aluminium alloy 6082 T6 is well weldable by classical fusion welding processes (MIG and TIG), while aluminium alloy 2024-T351 is almost non-weldable. For the welding of these two Al al...
Polymers and polymer composite materials, due to their properties, are becoming increasingly important materials in industry. They are used in a wide range of applications in space and aerospace, aviation, marine and automotive industry, as well as in production of sports equipment, household appliances, medical equipment, etc. They are expected to...
A hot-rolled clad plate made of 316L stainless steel and S355 carbon steel was produced in a real industrial environment via GMAW welding, vacuuming, preheating to 1240 °C, and hot-roll bonding on four stand plate mills in nine passes with reduction rates between 20-6% per pass. The clad plates were solution annealed to achieve the usual delivery c...
We studied the shear bond strength (SBS) of two PEEK composites (BioHPP, BioHPP plus) with three veneering composites: Visio.lign, SR Nexco and VITA VM LC, depending on the surface treatment: untreated, sandblasted with 110 μm Al2O3, sandblasted and cleaned ultrasonically in 80% ethanol, with or without adhesive Visio.link, with applied Visio.link...
This study presents a comprehensive experimental investigation of the high-cycle fatigue (HCF) behaviour of the ductile aluminium alloy AA 5083-H111. The analysed specimens were fabricated in the rolling direction (RD) and transverse direction (TD). The HCF tests were performed in a load control (load ratio R = 0.1) at different loading levels unde...
The impact and fracture toughness of a nanostructured, kinetically activated bainitic steel was determined using Standard methods. Prior to testing, the steel was quenched in oil and aged naturally for a period of 10 days in order to obtain a fully bainitic microstructure with a retained austenite content below 1%, resulting in a high hardness of 6...
Welded structures place increasing demands on the level of increased resistance to fracture. A large number of fractures of welded structures, which occur during exploitation at a stress level below of the allowable, indicates the danger of brittle fracture. The assessment of brittle fracture susceptibility was analyzed by testing Sharpy specimens,...
An investigation of the fatigue behaviour of the re-entrant auxetic structures made of the aluminium alloy AA 7075-T651 is presented in this study. The analysed auxetic structures represent a new class of cellular structures that show anomalous deformation responses such as negative Poisson’s ratio. In the proposed work, the influence of the unit c...
In the last decades, advances in steel manufacturing made possible the use of high-strength steel (HSS) and ultra-high strength steel (UHSS) for several applications, such as bridges, cranes, offshore structures, oil pipelines and automotive parts. Capacity of withstanding loads with reduced cross-section and minimum weight could be efficiently inc...
Heat-affected zones (HAZs) in real welds are usually quite narrow, and consequently most standard mechanical tests are difficult or even impossible. Therefore, simulated microstructures are often used for mechanical tests. However, the most often used weld thermal cycle simulator produces only a few millimeters wide area of simulated microstructure...
This study presents the experimental and computational investigation of a damage evaluation of the ductile aluminium alloy AA 5083-H111. The Compact Tensile (CT) specimen was selected for experimental testing and computational analysis. The proposed computational model is based on the inelastic energy approach, including the damage initiation and d...
MIG / MAG welding with solid or flux cored welding wire and TIG welding are most important arc processes for industrial application. In last period, laser welding become more and more important in industrial welding and cladding applications. Optimum selection of welding process for specific application include more important parameters like produc...
A very important segment, which occurs as a result of welding, is the occurrence of residual stresses in welded structures. The effects of residual stresses can be beneficial or harmful to the structure, depending on their size, sign, and stress distribution in relation to the stresses caused by the external load itself. Therefore, the examination...
In order to assess the integrity of welded pressure vessel containing a crack, the behavior of three-point bending specimens made of HSLA steel welded joint are tested at -40°C, and their fracture behaviour analyzed, as a conservative measure of crack resistance. Specimens were made of low-alloyed steel NIONIKRAL 70, welded by SAW process. Surface...
Hydroxyapatite (HAp) has long been considered the gold standard in the biomedical field, considering its composition and close resemblance to human bone. However, the brittle nature of hydroxyapatite (HAp) biomaterial, constrained by its low fracture toughness (of up to 1.2 vs. 2-12 MPa m 1/2 of human bone), remains one of the significant factors i...
The fabrication of biomaterials to be used in segmental bone defects, mimicking the bone's organic-inorganic architecture and mechanical properties to induce osteogenesis, persists as a key challenge. The purpose of this study was to elucidate the effect of a lightweight, morphologically graded, and multiphase self-standing scaffold structure prepa...
The presented paper deals with the mechanical properties of Friction Stir Welded (FSW) AA2024-T351-joints. The material’s response to the static and fatigue strength (S−N curve) is summarised from previous work and referenced, while the testing methods and results for the fatigue and fracture mechanics’ parameters regarding to the fatigue crack gro...
In order to ensure a quality welded joint, and thus safe operation and high reliability of the welded part or structure achieved by friction stir welding, it is necessary to select the optimal welding parameters. The parameters of friction stir welding significantly affect the structure of the welded joint, and thus the mechanical properties of the...
The high-strength low-alloy steel S1100QL is used in the most demanding mechanical engineering applications. Typical structures made of this steel are hydraulically extendable pallet cranes in mobile lifting machinery, which require high strength-to-weight ratio. The high yield strength and toughness of S1100QL steel is achieved through proper chem...
Appropriate post weld heat treatment (PWHT) is usually obligatory when creep resistant steels are welded for thermal power plant components that operate at elevated temperatures for 30-40 years. The influence of different PWHTs on the microstructure, hardness, and impact toughness of simulated heat affected zone (HAZ) subzones was studied. Thereby,...
The modification of a metal implant surface with a biomimetic coating of bone-like anisotropic and graded porosity structures to improve its biological anchorage with the surrounding bone tissue at implanting, is still a high challenge. In this paper, we present an innovative way of a gelatin (GEL) dip-coating on Ti-6Al-4V substrates of different s...
In this investigation, a T-joint numerical welding simulation of thick steel plates is performed to estimate transient temperature distributions, residual stress field and model deflections. A sequential simulation method is applied in the numerical simulation, where the thermal analysis is done by using the EBD technique to simulate the weld wire...
The aim of this study is to analyze how the process parameters affect the mechanical properties of butt joints obtained by friction stir welding (FSW). The experimental study was performed by the FSW of sheets having a thickness equal to 6 mm and made of aluminum alloys AA2024 T351, varying the process parameters, namely rotational speed and weldin...
The nanocomposites were prepared by synthesizing (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO)-oxidized cellulose nanofibrils (TCNFs) or cellulose nanocrystals (CNCs) with hydroxyapatite (HA) in varying composition ratios in situ. These nanocomposites were first obtained from eggshell-derived calcium and phosphate of ammonium dihydrogen orthophos...
The aim of this paper is to analyze the influence of the dominant parameters of Friction Stir Welding (FSW) on the mechanical
properties of welded joints. Experimental investigations were carried out on 6-mm-thick plates made of the aluminum alloy AA
2024 T351. The rotation speed of the FSW tool was a constant 750 min-1, and the welding speed was (...
The presented paper deals with the mechanical and fatigue properties of the alloyed aluminium alloy AA-2024 welded by the Friction Stir Welded (FSW) process. Using the optimized tool and welding procedure, 6 mm thick plates made of about quoted material were connected. In the first part of the paper, the influence of welding speed on the microstruc...
This paper presents a method for estimating the residual-strength of welded pressure vessel made of HSLA steel which contains a surface axial crack. In order to analyze the behavior of the structure, a set of specimens were extracted from the welded plates using the same welding procedure as used for welding of the vessel. Before the fatigue precra...
The paper presents the results of structural and mechanical testing of the alloyed aluminum alloys AA 2024 welded by the FSW process. Investigations were conducted on the welding machine, built on the base of the conventional, vertical milling machine. The goal of the research was to know the relationship between welding parameters and mechanical a...
This work investigates the feasibility of manufacturing a near net shape structural part directly on a subassembly for application in crane construction without post-machining. Single- and multi-pass welding experiments, using the Cold Metal Transfer process (CMT), were executed to identify and verify suitable process parameters. The obtained param...
Modern thermal power plant operating on fossil fuels has to be highly efficient and should emit low levels of CO2. One of possible ways to fulfil these requirements is to increase thermal power plant peak service temperature. P92 steel enables service temperature of up to 650 °C. It is stronger, more resistant to creep and enables higher service te...
Numerous structural components made of high strength low-alloyed steels are often exposed to lowcycle
fatigue loading during their exploitation life. In order to study the fatigue behavior of one grade
of structural steels produced in Yugoslavia during the eighties of the last century, a push-pull constant
amplitude strain-controlled fatigue tests...
The article describes two methods for measuring residual stresses that differ in the method of measurement. The first method, a method of energy X-ray diffraction, uses atomic planes as measurement sheets and it operates based on the principle of X-ray diffraction.The second method, the hole drilling method, measures residual stresses with resistan...
The investigation of the fatigue behaviour of an auxetic cellular structure made of Al-alloy 7075-T651 is presented in this study. The complete fatigue process of the analysed cellular structure is divided into the crack initiation (N i )and crack propagation (N p )period, where the total fatigue life (N t )is defined as the sum of N i and N p . Th...
V članku sta opisani dve različne metodi za mjerjenje zaostalih napetosti, ki se razlikujeta po principu merjenja. Prva metoda uporablja atomske ravnine, kot merilne lističe in deluje na principu odboja rentgenske svetlobe. Ta metoda se imenuje energetska rentgenska difrakcija. Druga metoda meri zaostale napetosti z uporovnimi merilnimi lističi, ki...
The paper deals with the numerical simulation and experimental investigations of a buried‐arc welding process on a butt‐welded plate sample. In the numerical investigations, the finite element analysis is carried out by applying the element birth and death technique in the thermal analysis, while the mechanical analysis is performed simultaneously...
Weld joints consist of base material, heat affected zone (HAZ) and weld metal. Load carrying capacity of the weld joints depends
on the weakest part of the microstructure in welded joint, especially at cyclic loading. Weld joint usually can consist small defects,
which are much smaller of sensitivity of NDT methods for weld joint inspection. In tho...
Weld cladding or weld overlay is a frequently used method for repair welding of damaged surfaces and for production of different surface coatings. The conventional coated electrodes have a circular cross-section. In order to increase the productivity and to decrease dilution and the depth of the heat affected zone (HAZ), the geometry of the electro...
The paper analyses the impact of the tool geometry on the friction stir welding (FSW) method on fracture toughness values of the base metal (BM) and weld metal (WM) of a butt welded joints of a high strength aluminium alloy. Values of fracture toughness were obtained using single-edge notched bend (SENB) specimens with fatigue pre-crack sampled fro...
Structural components which are loaded in cyclic load mostly fail due to fatigue. The fatigue strength of metals as
well as weld joint regions in metals depends on mechanical properties especially hardness, the size of defect and
the size of grains. Resistivity of the fine grain HAZ prepared against fatigue crack initiation will be explained in thi...
This paper will present the analyses of influence of application of activating flux on the mechanical properties of the welded joint in plasma welding of austenitic 316L class steel. In addition to standard mechanical tensile test, hardness measurements, Charpy impact test, using elastic-plastic fracture mechanics, the opening of the crack tip at t...
The paper presents the results of structural and mechanical testing of the alloyed aluminum alloys AA 2024 welded by the FSW process. Using the optimized tool and welding, 6 mm thick plates were connected. In this paper, the influence of rotation speed and welding speed on the macrostructure and cross section micro hardness of FSW welded joints of...
Since dielectric elastomer actuators are commonly used as artificial muscles, different approaches in material parameters identification have been used. Most dielectric actuators are parametrized with the help of continuum mechanics. Alternatively, rheological models can be used. Unfortunately, in basic rheological models, frequency dependence of v...
Beyond providing barrier function, the advanced materials in guided tissue regeneration (GTR) concept are further prompt to foster regeneration of distinct interfacing tissues. Herein we develop chitosan (CHT)/gelatin (GEL) bilayer membranes via successive solvent– and freeze–casting procedures and genipin (GEN) cross-linking chemistry. By utilizin...
Weld joint mostly fail in the critical zone known as heat affected zone. At structural components which are represented to cyclic load, fatigue is the reason for the failure of these components. The fatigue strength of metals as well as weld joint regions in metals depends on mechanical properties, the size of defect and the size of grains. Mechani...
The paper analyses the impact of the tool geometry on the friction stir welding (FSW) method on fracture toughness values of the base metal (BM) and weld metal (WM) of a butt welded joints of a high strength aluminium alloy. Values of fracture toughness were obtained using single-edge notched bend (SENB) specimens with fatigue pre-crack sampled fro...
This paper presents the application of activating flux on plasma welded joint on austenitic steel 316L and its influence on mechanical properties of the joint. In addition to standard mechanical tensile tests, hardness measurements, Charpy impact tests, and standardized SENB tests, using elastic-plastic fracture mechanics, were performed as well as...
The fatigue properties of friction stir welds (FSW) in 2024-T351 alloys have been investigated. In this paper, the influence of rotation speed and welding speed on the fatigue properties of friction stir welds (FSW) in EN AW-2024 T351 an aluminum alloy is investigated. The paper presents the results of structural and mechanical testing of the alloy...
Influence of welding speed on mechanical properties of two weld joints welded by Friction Stir Welding (FSW) were studied in this paper. In this research homogenized and artificially aged multicomponent Al-Zn-Mg-Cu alloy was used as a base material. Tensile tests, hardness measurements, instrumented impact Charpy tests, fracture mechanics SENB test...
The goal of this investigation was to find out the influence of usage of the two active powders, which were made by two different producer, on properties of welded joints on stainless steel 316 L welded by A-plasma welding process. The 6 mm thick plates of stainless steels 316 L were used for welding. Investigation reveal that the all welded joints...
Aluminijum je posle čelika najznačajniji građevinski material, iako nema dugu istoriju primene u građevinarstvu. Građevinske konstrukcije od aluminijuma potencijalno mogu naći veliku primenu zahvaljujući dobroj korozionoj postojanosti, lakoći legure, otpornosti na krti lom itd. U ovom radu opisan je uticaj zavarivanja trenjem sa mešanjem na struktu...
Determining the time of execution is very important in the early stages of each project (e.g. making offers, design phase etc.), especially in the stage of planning. This paper presents our approach to estimating the welding time for the purposes of planning the manufacturing processes. The approach is based on the knowledge of welding experts from...
Nanostructured hydroxyapatite (HAp) is most favorable candidate biomaterial for bone tissue engineering because of its bioactive and osteoconductive properties. Herein, we report for the first time ultrasound assisted facile and economic approach for the synthesis of nanocrystalline hydroxyapatite (Ca10 (PO4 )6 (OH)2 ) using recycled eggshell bio-w...
In this paper, the influence of rotation speed and welding speed on the impact strength, microstructure and cross section micro hardness of FSW welded joints of Al-Zn-Mg-Cu high strength aluminium alloy is studied. Rotation speed was varied from 750 min−1 to 850 min−1 and welding speed from 60 mm/min to 80 mm/min. It was found that the energy of cr...
Bone is composed of organic and inorganic material such as collagen and hydroxyapatite (HAp)
minerals forms hierarchical structure over a range from micro to nanoscale. The structure of bone
consists of self-arranged collagen fibres and HApnano crystals at nanometre length scale. The
mechanical properties of bone are characterized by the hierarchic...
Digital identification and evaluation of the fatigue damage accumulation kinetics on the surface of the fatigue sensor from steel 17Mn1Si is performed using the digital image processing method. The accumulation of defects was assessed based on the analysis of the diagnostic results for individual stages of cyclic deformation. It is established that...
In the present study, a three-dimensional numerical simulation of a T-joint fillet welding of two plates is performed using simplified material properties. To investigate the influence of the temperature-dependent thermo-mechanical material properties of carbon steel on the transient temperature distributions and weld-induced residual stresses and...
The analysis of the energy of fracture of specimens from steel OSL, which is widely used for the manufacture of railway axles under shock loading, is performed. The nature and quantitative parameters of the typical stages of the processes of plastic and brittle fracture, depending on the test temperature and stiffness of the stress state at the tip...
Bioceramic hydroxyapatite (HAp) is the major constituent of human hard tissue, and as such well-known and valuable implant material suitable for orthopedic and dental applications. The performance of HAp materials depends on its chemical compositions and structures. In the present study we have investigated the optimization of mechanical properties...
Metastable austenite stainless steel AISI 316L is sensitive to cold deformation, where transformation from austenite to martensite occurred. The bending deformation as the formation process leads to tensile and compression troughout the thickness of the billet. Tensile testing of the specimen causes differences in the true stress-strain along the c...
In the current paper, the main regularities in fracture of the railway axle steel have been found. It is established that the energy intensity of the steel fracture is connected with the deformational manifestations at the meso and macrolevels. As a part of the methodology of mesomechanics, the deformation behavior of the locomotive axis material h...