Effect Of Electron Beam Welding Research Articles

Дослідження технології зварювання плавленням складнолегованих титанових сплавів

The subject of this article is peculiarities of weld seam formation of complex titanium alloys during electron beam welding in vacuum and argon arc welding. The purpose of this study is to ensure the required level of mechanical properties of welded structures from complex titanium alloys to improve the structure and properties of welded joints. The task: to investigate the processes that are taking place in the zone of thermal influence and to determine their influence on defects formation; to determine the modes of parts welding made of complex titanium alloy; to study the effect of electron beam welding on the materials properties, such as strength, crack resistance, and corrosion resistance. Research results. The thermal cycle influence of welding and subsequent heat treatment on the structural and phase transformations in the weld metal and the heat-affected zone of complex titanium alloy welded joints was studied. It was established that a structure with a metastable β-phase predominance is formed in the weld metal and the zone of welded joints thermal influence, which contributes to the reduction of plasticity and impact toughness. The best combination of the studied welded joint strength and ductility was obtained after heat treatment, annealing at a temperature of 950 °C for 1 h, and cooling in the furnace. The use of filler wire contributes to obtaining an almost uniform structure and the disintegration of metastable phases in the seam as well as in the zone of thermal influence, and the strength limit is 1250 MPa. Conclusions. The influence of filler wires on the obtained samples structure and properties was studied, and the results were discussed depending on possible practical implementations. This article describes the creation and testing of elements of electron beam welding of complex titanium alloys technological process. This makes it possible to widely use welded combined titanium alloys in products of the appropriate purpose. The obtained scientific and practical results lead to increased mechanical properties of complex titanium alloys welded joints to the level of the base metal.

Особливості електронно-променевого зварювання магістральних трубопроводів з титанового сплаву

Titanium alloys have high strength and satisfactory weldability. They are widely used in the production of aircrafts and other structural elements in the modern aerospace industry. However, due to a high requirement for aviation and rocket-space technology, increasing the reliability and durability of responsible purpose remains an urgent issue. In this study, the results of welding tubular billets with an electron beam are presented. The subject of this article is the features of tubular billets made of complex titanium alloy electron beam welding. The purpose of this work is to ensure that welds of tubular work pieces have a high level of mechanical properties, based on the welding modes experimental testing results. To achieve this goal, the following tasks were set up and solved in this work: to investigate the mechanism of pore formation in welded joints; to study the effect of electron beam welding on the properties of the weld; ensure high indicators of physical and welded joints mechanical properties. The following research results were obtained. It was possible to obtain satisfactory characteristics of the welded joint by welding in the lower position on the substrate and in the horizontal position. The use of heat treatment increases the strength of welded joints to the level of the base metal. Welded seams, regardless of the welding method, have a coarse-grained structure with liquefaction heterogeneity, which is manifested in uneven etching of the seam. Conclusions: Various metallurgical aspects of titanium electron beam welding were studied. During electron beam welding of tubular blanks, pores are formed mainly near the fusion zone and in the seam axis. Edge mechanical processing, speed reduction, work piece rotation, and welded metal remelting dramatically reduce the number of pores in seams welded in the lower position. Crater removal with a stationary work piece avoids root defect formation in the area of annular seam closure. The obtained results have scientific and practical value in the welded joints of tubular blanks mechanical properties improvement.

Numerical investigation of the impact of thermoelectric effect on electron beam welding of dissimilar materials

Electron beam welding of GH4169 and Ni is required in the manufacture of the regenerative cooling system of the liquid rocket motor. The thermoelectric effect is observed during the welding of dissimilar metals; however, there has been a lack of investigation into the influence of this effect on electron beam welding joint formation and its dependence on test plate thickness. The thermoelectric effect of electron beam welding between GH4169 and Ni with varying thicknesses, as well as the influence of induced magnetic fields on electron beam trajectories, are investigated through the establishment of a numerical model incorporating thermal-electric-magnetic coupling.The results show that when the test plate increases from 2.5 mm to 10 mm the peak current density increases from 5.1 × 106 A/m2 to 7.6 × 106 A/m2, and the maximum magnetic flux density increases from 1.49× 10−2 T to 1.77 × 10−2 T. The increase in magnetic flux density results in a greater displacement of the electron beam spot away from the interface between the two materials, thereby causing incomplete fusion defects in the joints. This study elucidates the fundamental physical principles underlying the occurrence of incomplete fusion defects in electron beam welding joints, thereby furnishing essential theoretical underpinnings for enhancing the quality of dissimilar metal electron beam weld joints.

Effect of Electron Beam Welding on the Microstructure and Mechanical Properties of Low-Cost Titanium Alloys

An expansion of titanium to mass production industries, such as the automotive, is prevented by its high extraction and production costs (e.g. extraction of titanium from its ores is 15 times and 3 times higher than that of iron and aluminum, respectively). One possible way to reduce the cost of titanium is to use cheaper alloying elements instead of vanadium or niobium to stabilize the body-centered-cubic β-phase. Iron has been considered for the development of few low-cost titanium alloys, such as the Ti–2.8Al–5.1Mo–4.9Fe, Ti-1.5Al-6.3Mo-4.4Fe and Ti-3.6Fe-0.25O alloys, because of its stabilizing effect of the β-phase. Nevertheless, due to the high density of iron, high quantity of β-stabilizing elements and the formation of TiFe-based brittle intermetallic phases, welding joints of low-cost titanium alloys are prone to formation of cold cracks which is very important limiting factor for obtaining welded joints with a strength of at least 90% compared to the strength of base material. Electron Beam Welding with its higher welding speed and intensity used in the process has its advantages over other welding methods in achieving the higher temperature required for melting and joining titanium alloys and obtaining welds with better mechanical properties. In this work the influence of the electron beam welding thermal cycle on the structure and mechanical properties of low-cost titanium alloys Ti–2.8Al–5.1Mo–4.9Fe, Ti-1.5Al-6.3Mo-4.4Fe and Ti-3.6Fe-0.25O will be studied.

The Effect of Electron Beam Welding on the Microstructure and Microhardness of 3D-Printed Products from Titanium Alloy Ti–6Al–4V

The microstructure of double-sided welded joints of 3D-printed items made of titanium alloy Ti‒6Al–4V by the electron-beam freeform fabrication (EBF3) method has been investigated using the methods of X-ray diffraction analysis, optical metallography, and scanning and transmission electron microscopy. It is found that columnar epitaxial growth of primary β grains with transverse dimensions close to the sizes of primary β grains in the base material occurs in the process of electron-beam welding with a double-sided welded joint. Inside the primary β grains, there are grains of the α-phase with a lamellar shape inherited from the α' martensite, which is formed in the course of transformation β → α'. As in the printed samples, there is a nanocrystalline α"-phase in the metal of the welded joint inside grains of the α-phase and in interlayers of the β-phase. However, the density of particles of this phase in the metal of the welded joint is higher than in the base material. In the metal of the welded joint, tensile macrostresses and elastic residual microstrains also increase. The microhardness of the metal of the welded joint is greater than the microhardness of the base material.

Electron Beam Welding of TMCP steel S700MC

The article discusses tests aimed to determine the effect of electron beam welding on the properties of butt welded joints made in 10 mm thick TMCP steel S700MC. The welding process was performed in the flat position (PA) using an XW150:30/756 welding and surface processing machine (Cambridge Vacuum Engineering). The joints obtained in the tests were subjected to non-destructive tests including visual tests and magnetic particle tests. The joints were also subjected to destructive tests including static tensile tests, bend tests, toughness tests (performed at a temperature of -30°C), hardness tests as well as macro and microscopic metallographic tests. The destructive tests revealed that the joint represented quality level B in accordance with the PN EN ISO 13919-1 standard. The analysis of the destructive test results related to the electron beam butt welded joint (made in steel S700MC) revealed its high mechanical and plastic properties. The toughness tests revealed a decrease in toughness in the HAZ (27 J/cm2) in comparison with that of the base material (50 J/cm2). In addition, the hardness of the HAZ and of the weld increased up to approximately 330 HV; the hardness of the base material amounted to 280 HV.

Effect of post-weld heat treatment on microstructure evolution and pitting corrosion resistance of electron beam-welded duplex stainless steel

The effects of electron beam welding and subsequent post-weld heat treatment at different temperatures on the microstructure evolution and pitting corrosion resistance of duplex stainless steel were investigated. The as-welded joint exhibited poor pitting corrosion resistance, and pitting preferentially occurred at the ferrite grain in the weld. Heat treatment promoted austenite formation, Cr2N dissolution, and eliminated dendritic segregation, consequently improving the corrosion resistance of the welded joint. The optimal solution temperature range was 1050–1110 °C. The austenite in the weld was prone to selective corrosion after heat treatment owing to its lower pitting resistance equivalent number.

Effect of Electron Beam Welding and Heat Treatment on the Structure and Properties of Technical Titanium with an Alloying Dope of Boron

Effect of Electron Beam Welding and Heat Treatment on the Structure and Properties of Technical Titanium with an Alloying Dope of Boron

Effects of Electron Beam Welding on Microstructure, Microhardness, and Electrical Conductivity of Cu-Cr-Zr Alloy Plates

In this study, the effects of electron beam welding on the microstructure, microhardness, and electrical conductivity of precipitation-hardened Cu-0.804%Cr-0.063%Zr (wt.%) alloy plates were investigated. Experiments were carried out following a central composite design of experiments. Five welding schedules yielding the higher hardness were chosen and then were subjected to standard metallographic and various microscopy techniques to reveal the type, morphology, and distribution of the precipitates and to obtain the sub-structural information from the weld zone. X-ray diffraction studies revealed predominant formation of intermetallic phases in the welded zones of some of the samples, which could have resulted in higher hardness and better electrical conductivity compared to those of other ones. Microhardness values in the fusion zone and heat-affected zone were found to be less than that of the parent material. The mechanism of damage in Cu-Cr-Zr plates due to welding was also explained.

Experimental investigations, input-output modeling and optimization for electron beam welding of Cu-Cr-Zr alloy plates

Precipitation-hardened Cu-0.804Cr-0.063Zr alloy is a potential material to be used for the fabrication of heat sinks in International Thermonuclear Experimental Reactor (ITER) applications. The softening temperature of these alloys is 500 °C, which makes it suitable for the fabrication of components subjected to high heat flux. During welding, the precipitates get completely dissolved in the melted zone, which results in lower hardness and softening temperature. The aim of this study was to understand the effects of electron beam welding (EBW) on weld bead geometry and mechanical properties of this alloy. Accelerating voltage, beam current, welding speed, and focusing distance were selected as input variables, and bead geometric parameters like bead width, bead penetration, and microhardness values of the fusion and heat-affected zones were considered as outputs. Statistical regression analysis was conducted to determine input-output relationships. All the above input parameters were found to have significant contributions toward bead penetration and microhardness of fusion zone. However, accelerating voltage did not have significant contribution toward bead width. Optimization was done to obtain minimum weldment area after satisfying the conditions of maximum bead penetration and minimum deviation of the hardness of fusion zone from that of parent material. This constrained optimization problem was solved using a genetic algorithm along with a penalty function approach for handling the functional constraints. A good agreement was obtained between the results predicted by the optimization tool and that of real experiments. Thus, the genetic algorithm (GA) could accurately establish input-output relationships of this process.

Electron beam assisted joining of nanograin-sized Fe–Co–V magnetic foils: Study and optimization of magnetic properties of weld joints

Fe–Co–V alloys are of interest due to their excellent magnetic properties. These alloys are frequently used in the active parts of rotors of synchronous hysteresis motors. Welding of these alloys is however a great challenge because of various phase transitions occurring during solidification. These phase transitions change the microstructural, physical and mechanical properties of Fe–Co–V alloys. In this research work, the effect of electron beam welding on the magnetic properties of nanograin-sized Fe–Co-7.15wt%V foils was studied. Microstructural observation and texture analysis were carried out in order to clarify the changes of magnetic properties in the welded area. It was found that the magnetic properties of the welded area experience significant decrease due to the formation of large grains that have unfavorable orientation in the fusion zone. Also, a statistical analysis of the electron beam welding of this alloy was done using response surface methodology. The analysis considered the effect of beam current (0.7–1.7 mA), beam voltage (40–50 kV), welding speed (150–500 mm/min) and focused position (−20 to 0 mm) on the energy product ((BH)max) of welded samples. The experimental design was based on four-factor, five-level central composite rotatable design using linear and quadratic polynomial equations for proposing the mathematical model.

Effect of Electron Beam Welding on Microstructure and Mechanical Properties of Spray-Deposited Al-Zn-Mg-Cu Alloy

In this study, Al-8.6Zn-2.6Mg-2.2Cu (wt,%) alloy was synthesized by the spray atomization and deposition technique. Electron beam welding (EBW) joint in the spray-deposited Al-8.6Zn-2.6Mg-2.2Cu alloy is composed of fusion zone, heat affected zone and base metal region. The microstructure of the fusion zone has been found to be very fine equiaxed grains, and the microstructure of the heat affected zone is mainly composed of α-Al and Al/MgZn2 eutectic microstructure. Extensive microhardness measurements were conducted in the weld regions of the nuggets exhibited a hardness loss in the fusion zone due to the loss of strengthening phases. Tensile properties test results indicated that tensile strength of these welds approached 82.3~85.3% of the base metal. The analysis of fracture surface has confirmed that the specimen fractured within the weld region during tensile test.

Measurement and Simulation of Residual Stresses of Electron Beam Welding Joint of Pure Aluminum

The effects of electron beam welding on the residual stresses of welded joints of pure aluminum plate 99.60 are studied by through-hole-drilling and blind-hole-drilling method. Meanwhile, based on the thermal elastic-plastic theory, and making use of ANSYS finite element procedure, a three - dimensional finite element model using mobile heat source of temperature and stresses field of electron beam welding in pure aluminum is established. The welding process is simulated by means of the ANSYS software. The results show that the main residual stress is the longitudinal residual stress, the value of the longitudinal residual stress is much larger than the transverse residual stress. But the residual stress in the thickness is rather small. And in the weld center, the maximum value of residual stresses is lower than its yield strength. The simulation results about the welded residual stresses are almost identical with the experimental results by measuring. So the research result is important to science research and engineering application.

Effect of electron beam welding on fracture behaviour of thick TC4-DT alloy

Fracture toughness of a damage tolerant Ti6Al4V (TC4-DT) alloy and its electron beam welded joint was investigated using compact tension specimens. Moreover, tensile test, microhardness test and microstructure examination were carried out. The result indicates that the weld metal is strength overmatching. The tensile strength and microhardness of the weld metal are higher than those of the base metal, but the ductility and the energy absorbed before fracture are lower. In addition, the fracture toughness K1c of the base metal is relatively high. The fracture toughness of the weld metal decreases compared with the base metal. It is expected that the toughness reduction of the weld metal is mainly related to the as solidified coarse β columnar grain structure containing martensite in comparison with the bimodal structure of the base metal. Moreover, fractographic observation shows that the fracture mode of both weld and base metals is found to be ductile.

Effect of electron beam welding on the microstructures and mechanical properties of thick TC4-DT alloy

Electron beam welding (EBW) was applied to 50 mm thick damage-tolerant Ti–6Al–4V (TC4-DT) alloy, and microstructure, microhardness and tensile properties of the defect-free welded joints were examined. The results indicated that the microstructure of the base metal is composed of primary α phases and the lamellar (α + β) bimodal structure. For the EBW joint, martensite basketweave microstructure is formed in fusion zone (FZ). Moreover, the heat affected zone (HAZ) near FZ consists of acicular martensite and a small portion of primary α phase. The HAZ near base metal consists of primary α phase and transformed β containing aciculate α. It is found that the boundary of the two portions of the HAZ was dependent on the β phase transus temperature during weld cooling. Microhardness values for FZ and HAZ are higher than that of base metal, and there are the peak values for the HAZ near the weld metal. The fracture locations of all the EBW tensile specimens are in base metal, and the ultimate tensile strength of the joints may reach about 95% of the base metal. In addition, with the depth increasing along the weld thick direction, the grain size of the FZ decreases and microhardness increases.

Investigations into the effects of electron beam welding on thick Ti–6Al–4V titanium alloy

Electron beam welding (EBW) of titanium alloy Ti–6Al–4V is not an easy task and finding the correct welding parameters is one of the critical activities when the product is intricate in shape. The procedure adopted to weld 17.5 mm thick joint in a spherical titanium gas bottle using EBW is presented here. Available EBW machine was capable of welding full penetration joint only up to 12.5 mm in titanium. Single sided partial penetration weld yielded poor result in production welding due to repeated defects like lack of fusion, root porosities, weld bead depression, under cut, etc. A two-pass double side welding technique was developed, and a joint thickness of 21 mm was decided so that a partial penetration weld can be attempted with lesser beam power. The extra material kept at the root of the weld can be machined off after welding. Single pass was made from one side of the joint producing a partial penetration weld with a penetration of nearly 19 mm. The second pass was made from the reverse side of the joint producing a similar partial penetration weld with almost the same penetration as that of the first weld. Trial welds were carried out and considerable difficulties were encountered in developing the welding procedure for establishing a defect free weld. Fusion zone voids and root porosities were observed and techniques were developed which eliminated their occurrence. Systematic weld qualification was carried out on coupon level and mechanical property and microstructure evaluations were carried out to ensure the joint integrity. Based on the technology developed and parameters arrived, the final specimen was welded. After passing through non-destructive tests, it was subjected to hydraulic proof pressure test with strain gauges and acoustic emission sensors for validating the capability of the technology developed. It has qualified all the test requirements as per the specifications and has been used for aerospace applications.

The effect of electron beam welding on various properties of three austenitic stainless steels

The influence of electron beam welding on various properties of semistable austenitic stainless steels: 304L, 316 (low nitrogen), and 21-6-9 were investigated. Tensile tests performed on transverse butt joints gave joint efficiences approaching 95% of theoretical efficiencies. The joint ductility for all steels, however, was 50 to 70% that of unwelded samples. Hardness testing revealed that the parent matrix was harder than the heat affected zone (HAZ) which in turn was harder than the fusion zone. Microstructural examination showed that the residual 11% cold-working had induced a partial martensitic transformation in the HAZ. The formation of (Fe, Cr)23(C, N)6 precipitate is responsible for the observed change in mechanical properties in the fusion zone. Electron microprobe analysis showed that a redistribution of the metallic elements (Ni, Cr, Mo) occurred in the fusion zone but that the nonmetals (P, S, Si) were relatively unaffected by the fusion process. Corrosion sensitivity tests showed that only the 304L steel was susceptible to corrosion cracking. Microstructural observations of failed surfaces of this steel reveal that fracture begins in a semi-brittle mode at the weld root and continues through the HAZ in a ductile manner.