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The aim of the paper is focusing on the brazeability of stainless steel AISI 304 and copper Cu-ETP (electrolytically tough pitch) dissimilar materials by electron beam. The thickness of base materials was 1 mm. Cusil eutectic brazing alloy (72Ag-28Cu, AWSBAg-8) in the form of thin foil was used as filler material. Overlapped joints were manufactured using defocused vertical electron beam. The effect of beam current on braze appearance, microstructure, and microhardness of brazed joints was investigated. The scanning electron microscopy indicated the possibility of obtaining defect-free joints. The results show that the binary Ag-Fe equilibrium diagram is expectedly the microstructure even at the moderate cooling and solidification rates expected under the used electron beam brazing conditions and parameters. Beam current is the main brazing parameter influencing the joint quality. Optimum brazing parameters were as follows: beam current 6 mA, brazing speed of 5 mm/s, and 50 passes at constant accelerating voltage (U = 55 kV), focusing current (If = 990 mA) across the upper material length—Cu.

The scope of this study was to ascertain the weldability of Nickel 201 alloy sheets using an electron beam welding method. Weld joints of the Nickel 201 alloy sheets 2,0 mm thick were welded by electron beam without an additional material at a flat position. The influence of electron beam welding parameters on weld quality and mechanical properties of test joints was studied. The study of quality and mechanical properties of the joints were determined by metallographic evaluation, tensile and hardness tests.

Production of multi-rifled seamless steel tubes employing cold draw process using multi-rifled mandrel is quite a modern technology. The important characteristic of the tube drawing process, unlike the tube with internal rifling, is the corner filling which influences the dimension accuracy of the internal shape of the tube. In this study, the influence of drawing tool dimensions and mandrel shape on to final rifling filling was investigated. Draw process has been simulated by using the three-dimensional rigid-plastic finite element method (FEM) by using DEFORM 3D software. The results of numerical simulation show that the shape of drawing tools and process conditions have a significant influence on the forming process and final shape and properties of the workpiece.

Study of weld joints of nonferrous, Inconel 625 alloy sheets using a new generation disk laser as the green welding technology for the effective manufacturing were carried out, and the results are presented in this paper. Weld joints of the Inconel 625 alloy sheets 2,0 mm thick were welded by laser without an additional material at a flat position, using a high purity argon as the shielding gas. The influence of laser welding parameters on weld quality and mechanical properties of test joints was studied. The influence of welding speed and laser power to the joint quality was investigated. The study of quality and mechanical properties of the joints were determined by metallographic evaluation, tensile and hardness tests.

This work deals with the study of ultrasonic soldering of SiC ceramics by use of Zn-Al-In solder destined for higher application temperatures. The structure and properties of this soldering alloy were assessed. The Zn5Al1In solder consists of βZn matrix, where the βZn + αAl a (In) eutectics in the form of oblong and spherical clusters are non-uniformly distributed. The tensile strength of soldering alloy attained the value of 52 MPa. The soldered joint of SiC/Zn5Al1In/SiC was fabricated at the temperature of 420 °C at simultaneous acting of ultrasonic vibrations. The bond was formed owing to the formation of two new thin layers of Al + Si and Zn + C on the surface of SiC substrate. The average shear strength of SiC/Zn5Al1In/SiC joint attained 49 MPa. The fracture has occurred not only in the solder bulk but also in a close vicinity of SiC substrate. In this zone, similarly as on the fractured surface in the solder zone, the presence of In was identified, in which a considerable measure affected the resultant strength values.

With the instrumentality of a newly developed fretting test bench for planar contacts, a state-of-the-art method of inter-mediate imaging helps to understand fretting wear mechanisms of different materials and lubricants. The test bench uses application like planar surfaces unlike the usual point or elliptical contact in model testing (with the tribological test chain). Applications considered prone to fretting wear have large planar contacts – like bearing seats and shaft hub connections – and contact pressures normally perceiv ed as low or uncritical. This article examines a method to evaluate a targeted observation of the surfaces. The method uses a movable upper sample to open the contact and to document an interim status of the test by image recording. Among other things, this is to obtain time-lapse recordings of the progressive wear and tear. Just opening the contact can already influence the tribological system and the result of a test. It is shown whether and how this opening process has an impact on tests with continuous contact.

A study of weld joints of nonferrous, Nickel 201 alloy sheets using a new generation disk laser as the green welding technology for effective manufacturing was carried out, and the results are presented in this paper. Weld joints of the Nickel 201 sheets 2.0 mm thick were welded by laser without an additional material at a flat position, using high purity argon as the shielding gas. The influence of laser welding parameters on weld quality and mechanical properties of test joints was studied. The influence of welding speed and laser power to the joint quality was investigated. The study of quality and mechanical properties of the joints were determined by metallographic evaluation, tensile and hardness tests.

The scope of this study is to ascertain the weldability of Inconel 625 alloy sheets using an electron beam welding method. Weld joints of the Inconel alloy sheets 2.0 mm thick were welded by an electron beam without an additional material at a flat position. The influence of electron beam welding parameters on weld quality and mechanical properties of test joints was studied. The study of quality and mechanical properties of the joints were determined by metallographic evaluation, tensile and hardness tests.

Deoxidized oxygen free copper C12200, 1 mm in thickness, was welded to 1-mm thick AISI 304 stainless steel with disk laser. The butt-welded joints were produced with different welding parameters. Full factorial design of experiment (DoE) approach consisting of three factors and two levels was utilized. Laser powers used for welding were 1.3 and 1.9 kW and welding speeds of 20 and 30 mm/s. Two beam offsets were tested, namely, 100 &mu, m toward copper side and 200 &mu, m toward AISI 304 steel. It was found that beam offset possesses the largest influence on the welded joints&rsquo, tensile strength. Tensile strengths attained values more than 3.7 times higher in comparison to the AISI 304 steel beam offset. When lower laser power was used, the higher tensile strength was attained for copper sheet offset. Higher microhardness was observed when laser beam was offset to AISI 304 steel side. The average microhardness of the weld metal was higher than that of the weaker base material, copper sheet. Energy dispersive X-ray spectroscopy (EDS) analysis confirmed the heterogeneity in elemental composition across the welded joint interface, being lower when laser beam was offset to AISI 304 steel side. On the other hand, the copper content dropped to the average composition of weld metal at the distance of about 140 &mu, m from copper-weld metal interface.

The microstructural characterization and properties of solder joints made from lead-free solder alloys SnAg3.0Cu0.5 and SnAg1.0Cu0.5Bi1.0 (composition given in weight %) with Cu plate were studied in this work. The influence of Bi addition to the SAC solder was studied. The melting temperatures, optical microscopy, EDX, and point chemical analyses were observed and evaluated. Thermo-Calc software was used for phase’s composition prediction. Altogether, 1500 cycles were carried out for the thermal cycling test in the range from +150 to − 40 °C where the solder joints’ reliability was assessed due to practice requirement. Optical microscopy and scanning electron microscopy (EDX microanalysis) tests were used for the evolution of microstructure and structural integrity of thermal cycled solder joints.

The joining of Ti and Ni at low temperatures was analysed in this work. For joining pure Ti and Ni coins of 1.5 mm in thickness were used. Reactive multilayer thin films/foils with nanometric period (bilayer thickness), in particular Ni/Al multilayers, have been used to promote joining in two thickness of 28 and 55 nm. The ultrasonic soldering with SnAgTi active solder has been used for “hard-to-solder” material. The structural evaluation of soldered joint was studied by optical microscopy and EDX analysis. The structural analysis was focused to the creation of intermetallic layers in the joint interface. The mechanical properties of solder joints were tested by shear strength.

The work is devoted to the study of direct soldering of a substrate of Al2O3 ceramics with a Cu substrate by use of Bi11Ag2La solder. Soldering was realised by fluxless method in air by activation with power ultrasound. It was found out that lanthanum is during the ultrasonic soldering process distributed to the interface with Al2O3 substrate, enhancing thus the bond formation. The bond with ceramic substrate has adhesive character without formation of a new contact interlayer. The shear strength of joint with Al2O3 ceramics is 20 MPa.

A new method of material and lubricant testing is demonstrated with a planar contact fretting wear tribometer under typical fretting wear conditions. The usual abstraction of contact geometries with an easy-to-align point or line contacts is deliberately dispensed to do justice to the frequently flat contacts of machine elements (shaft-hub connection, bearing seats, etc.). For the study, a new method of targeted observation of the contact surfaces during the test is used, which allows a time-lapse animation of the fretting wear progress of solid lubricant mixtures. Thus, the formation of possible transfer film build-up and the type of wear mechanism occurring can be visualized. This technique represents, in conjunction with additional analytical methods such as microscopy and SEM/EDX, a powerful tool to provide a better insight into the mechanisms of solid lubricant action under fretting conditions. To demonstrate the potential of this approach, a time to damage study is performed on commercial and self-prepared pastes from solid lubricants and white oil, where calcium hydroxide is a commonly employed solid lubricant for the avoidance of fretting wear is compared to other materials.

Duplex steels are an important group of materials which are generally used for applications where resistance to corrosion, or high strength and creep resistance at elevated temperatures, are required. They are used extensively in nuclear plant. Although ultrasonic inspection methods have been routinely used in industry for some three decades, it is well known that cast or welded austenitic components can be difficult, or even impossible, to examine ultrasonically. Development of ultrasonic techniques is therefore in progress in several countries to provide improvements which are being sought on safety and economic grounds.The aim of this paper is a brief description of the relevant metallurgical characteristics given before a consideration of the physical properties of the weld metal and the current theoretical models used to describe ultrasound propagation in it. The paper deals with the steps taken to improve the capabilities of ultrasonic inspection and includes a discussion of the problems of flaw location and sizing.

The non-destructive inspection of duplex steels is a big challenge, being composed of ferrite and austenite, have some particularities. When using ultrasound, for instance, its waves propagate well in ferrite, but suffer strong attenuation, scattering and refraction in austenite. The aim of this work is to use the Phased Array ultrasonic inspection method for the thin (4 mm) duplex steel weld joint inspection. The experimental sample was made ​​of duplex steel shaped tube with an outer diameter of 44 mm and a wall thickness of 3.8 mm welded with a laser beam. The experiment was necessary to verify attenuation of duplex steel. On the base material and the weld joint were made the artificial defects, in which the adjusted sensitivity of the ultrasonic device was set.The result of the measuring was the defect echo coming from the weld root layer. The length (about 25 mm) can only be estimated due to the inaccurate constant velocity of probe motion along the surface.

The use of non-destructive inspection techniques in conventional stainless steels is well established. However the non-destructive inspection of duplex and superduplex steels is a big challenge as those steels, being composed of ferrite and austenite, have some particularities. When using ultrasound, for instance, its waves propagate well in ferrite, but suffer strong attenuation, scattering and refraction in austenite. An extended research is proposed on the inspection of duplex steels, especially in welded joints, which presents the worst problems in those steels (incorrect ferrite/austenite balance and precipitation of deleterious phases). The aim of this work was to use the TOFD ultrasonic inspection method for the thin duplex steel weld joint inspection.

Austenitic steel welds exhibit a heterogeneous and anisotropic structure that causes difficulties in the ultrasonic testing (UT) understanding. Increasing the material knowledge has been an international large and long term research field. The main specificity of the weld material is its oriented grain structure which has to be described as an anisotropic and heterogeneous material. The description of the grain structure regularly progresses from simplified and symmetrical structures to more realistic descriptions. This paper report some result of the weld joints fabricated by laser beam welding, experimental investigation of the ultrasonic inspection of duplex steels. Experimental studies have concentrated on methods of improving signal to noise ratio in these steels and on relating properties such as attenuation to material structure.

The paper deals with the research and development of lead-free solder for microelectronics in consideration of the environmental, economic, and qualitative aspects. The main aim of this paper is to study the influence of In additives to the complex properties of solder joints. The SnCu0.67In2.0 solder alloys were used for the research. They had been confronted with the most commonly used SnAg3.0Cu0.5 solder in the electronics industry in terms of melting temperatures, wetting properties, microstructures, and costs. Thermo-Calc software was used for phase’s composition prediction. The solder joint reliability was assessed to evaluate the thermal cycling test in the range from −40 to 150 °C. Altogether, 1,500 cycles were carried out. Solder joints were exposed to the thermal cycling due to practice requirement. Optical microscopy, scanning electron microscopy (EDX microanalysis), and shear strength test were used for the evolution of microstructure, structural integrity, and mechanical strength of thermal-cycled solder joints. Designed SnCu0.67In2.0 solder alloys reached the most suitable result for microelectronic.

The aim of this paper was the study of laser cladded layers applied in practice from the view of the internal structure of the material changes. In the process of cladding the laser beam was used as the heat source to melt and fuse the cladding alloy LS 30 onto the substrate - steel EN 1.2379.The filler material - wire diameter was 0.4 mm and the maximum height of the coating was 0.3 mm. The basic material was in minimal heat treated, in a very narrow intermediate layer with the character of diffusion joint. The cladded layers were evaluated for resistance to abrasive wear and topography of layers was performed. The proposed technology and the filler material have impact on the topography and roughness of the resulting layers.

The effects of Bi and In additions on intermetallic phase formation in lead-free solder joints of Sn–3.7Ag–0.7Cu; Sn–1.0Ag–0.5Cu–1.0Bi and Sn–1.5Ag–0.7Cu–9.5In (composition given in weight %) with copper substrate are studied. Soldering of copper plate was conducted at 250 °C for 5 s. The joints were subsequently aged at temperatures of 130–170 °C for 2–16 days in a convection oven. The aged interfaces were analyzed by optical microscopy and energy dispersive X-ray spectroscopy (EDX) microanalysis. Two intermetallic layers are observed at the interface – Cu 3 Sn and Cu 6 Sn 5 . Cu 6 Sn 5 is formed during soldering. Cu 3 Sn is formed during solid state ageing. Bi and In decrease the growth rate of Cu 3 Sn since they appear to inhibit tin diffusion through the grain boundaries. Furthermore, indium was found to produce a new phase – Cu 6 (Sn,In) 5 instead of Cu 6 Sn 5 , with a higher rate constant. The mechanism of the Cu 6 (Sn,In) 5 layer growth is discussed and the conclusions for the optimal solder chemical composition are presented.

The tin-based alloy Sn-1.5Ag-0.7Cu-9.5In (composition in wt.%) is a potential candidate for lead-free soldering at temperatures close to 200°C due to the significant amount of indium. Samples of Sn-1.5Ag-0.7Cu-9.5In were prepared by controlled melting of the pure elements, followed by quenching to room temperature. The samples were analyzed by scanning electron microscopy/energy-dispersive x-ray spectroscopy (SEM/EDS) and electron backscatter diffraction. The solidified melt consisted of four different phases. Solidification behavior was monitored by heat-flux differential scanning calorimetry (DSC). The phase equilibrium has been further investigated by thermodynamic calculations. The observed phase compositions as well as DSC signals are reasonably explained using the calculation of phase diagrams (CALPHAD) approach.

Ovdje se analizira utjecaj dodavanja Bi na stvaranje intermetalne faze u bezolovno lemljenim spojevima od Sn-Ag-0.5Cu0.5Bi (SAC0,5B) i Sn-Ag-0.5Cu-1.0Bi (SAC1,0B), sastav dan u težinskim %, na bakrenoj podlozi. Lemljenje bakrene ploče je provedeno na 255 °C u trajanju od 5 s. Spojevi su zatim ostavljeni na temperaturi od 100 °C, 130 °C i 160 °C u trajanju od 1, 3, 7, 15 dana u konvekcijskoj peći. Međupovršine su tada analizirane optičkim mikroskopom i energetskom disperzivnom rendgenskom spektrometrijskom mikroanalizom (EDX, JEOL-JXA-840A). Dva intermetalna sloja su zapažena na međupovršini - Cu3Sn i Cu6Sn5. Sloj Cu6Sn5 je nastao tijekom lemljenja. Sloj Cu3Sn je nastao tijekom sazrijevanja u čvrstom stanju. Dodavanjem Bi smanjuje se nastanak Cu3Sn jer se tako sprječava širenje Sn duž granica zrna. U članku se dalje raspravlja mehanizam nastanka sloja Cu6Sn5 i daju se zaključci za optimalni kemijski sastav lemila., The effects of Bi addition on the intermetallic phase formation in the lead-free solder joints of Sn-Ag-0.5Cu0.5Bi (SAC0,5B) and Sn-Ag-0.5Cu-1.0Bi (SAC1,0B), composition given in weight (measured in %), with copper substrate are studied. The soldering of the copper plate was conducted at 255 °C for 5 s. The joints were subsequently aged at temperatures of 100 °C, 130 °C and 160 °C for 1, 3, 7, 15 days in a convection oven. The aged interfaces were analysed by the optical microscopy and energy dispersive x-ray spectrometry (EDX, JEOL-JXA-840A) microanalysis. Two intermetallic layers are observed at the interface – Cu3Sn and Cu6Sn5. Cu6Sn5 is formed during soldering. Cu3Sn is formed during solid state ageing. Bi decreases the growth rate of Cu3Sn since it can possibly inhibit Sn diffusion along the grain boundaries. The mechanism of the Cu6Sn5 layer growth is discussed and the conclusions for the optimal solder chemical composition are presented.

The aim of this article is study the influence of Bi on the microstructure evolution of lead-free solder joints in microelectronics. The key factors affecting the reliability of electronic products are the interfacial reactions in solder joints, the secondary products of which are brittle intermetallic compounds. Formation and growth of intermetallic compounds are dependent from the chemical composition of solder and base material, from the effects time of the moltent solder on the base material and from the operating temperature. It is very important to mention that these reactions occur not only near the contact of the base material and molten solder in the process of melting and cooling the soldered joint, but they continue even after the solder solidifies.