Electron Beam Brazing Research Articles

The Effect of Temperature on Electron Beam Brazing of Titanium to Alumina Ceramic

The authors have investigated the effect of temperature on the composition and structure of the joint metal produced by electron beam brazing of titanium and alumina ceramic using a fore-vacuum-pressure, plasma-cathode electron source. We found that for brazing temperatures below the titanium polymorphic α-β transition temperature, conditions favorably affect the performance characteristics of the metal-ceramic joint produced. Based on these studies, a strong, tight metal-ceramic joint between titanium and alumina ceramic was obtained

Electron Beam Brazing of Titanium and Stainless Steel Dissimilar Joints with Ag-Based Filler

In this work, electron beam was used for butt brazing of austenitic stainless steel with grade 2 titanium. Due to its low solidus temperature and high silver content, AWS BAg-21 filler containing Ag, Cu, Sn and Ni was selected. The joints were brazed with a defocused oscillating beam using offset. The resulting brazed joints were subjected to static tensile testing, light microscopy, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) analysis and hardness tests. By using appropriate parameters it was possible to reduce the phenomenon of diffusion of titanium atoms into the joint, which improved the properties of the obtained joints. The maximum tensile strength obtained was 244.2 MPa.

Lutowanie wiązką elektronów na przykładzie stali austenitycznej odpornej na korozję – AISI 304

Electron beam brazing is a joining technology combining the advantages of a precisely controlled heat source and those of vacuum brazing process. The oxide layer decomposes in high-temperature vacuum conditions, which improves the wetting process and, consequently, leads to the obtainment of more favourable properties of the brazed joint. In comparison with brazing in vacuum furnaces, the electron beam brazing process enables the precise heating of selected areas without the necessity of heating the entire element, which, in turn, results in smaller structural changes in the brazed material and the lower consumption of energy. During tests discussed in this article, sheets made of stainless steel AISI 304 were brazed using various copper and silver filler metals. Brazed joints were subjected to microstructural tests and shear strength tests. The results revealed the high efficiency of the electron beam brazing of corrosion-resistant steel sheets using filler metals.

Feasibility study on feeding wire electron beam brazing of pure titanium using an electron gun for space welding

Vacuum electron beam brazing experiments of pure titanium TA2 with automated feeding AgCu28 wire as filler metal were carried out. The beam current and the welding speed could affect the welding heat inputs to affect the surface appearances, the microstructures and the tensile strengths of the brazed welds. The typical chemical microstructures of the brazed welds were composed of Ag-based solid solution, Ti2Cu and TiCu, meanwhile, α-Ti would exist at the interface under the higher beam current. Moreover, the higher welding speed would promote the loss of Ag-based solid solution. Both the uniform distribution of granular Ag-based solid solution and the existence of α-Ti phase could improve the tensile strength of the brazed joint. It implied that the new electron beam gun designed for space welding was dependable for brazing in the open space. It provides experience for the connection of titanium and titanium alloys in the space and provides the theoretical and experimental basis for its application in the space industry.

Quality of dissimilar welded particle-reinforced TRIP/TWIP steels generated by electron beam braze-welding

ZrO2-reinforced high alloy steels have a strong tendency for pore formation during thermal joining and are therefore considered as non-weldable. However, present investigations have shown that it is possible to join particle-reinforced steels by a dissimilar electron beam braze-welding with a beam offset. The joints were characterised by light optical microscopy (OM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) methods, such as electron backscatter diffraction (EBSD), energy dispersive X-ray spectroscopy (EDS) and selected area electron diffraction (SAED). The mechanical properties and the deformation behaviour of the welded material were studied in tensile tests. The quality and type of the joints depend on the dilution of the weld. The welds with a level of dilution between 2 and 10% are free of defects and show an epitaxial growth onto the base material which yields superior mechanical properties compared to the welds without dilution. The welds produced by electron beam brazing exhibited the formation of oxide films which prevented an epitaxial growth of the solidified material. Therefore, a significant impact on the results of the tensile tests was noticed.

Joining of TWIP-matrix composites by electron beam brazing

Zirconia reinforced, high alloy TWIP steels offer unique mechanical properties, due to the combination of stress- and deformation-induced phase transformations within the matrix and particles. However, these composites are considered as non-weldable, due to the strong evaporation of zirconia during fusion welding. In this work, an alternative approach for the joining of zirconia reinforced TWIP steels by electron beam brazing is presented. The electron beam was chosen as heat source due to its outstanding reproducibility of parameters, the independence of energy input from the materials surface, the inert vacuum atmosphere, and the flexibility of the energy transfer function. For the experiments, a stainless steel and a Fe-Cr-Mn-Ni-based TWIP steel reinforced with zirconia were brazed as butt joints with a Ni-based filler. The samples were characterized by light optical microscopy and EBSD measurements to evaluate the microstructure. Furthermore, Martens hardness and tensile tests were performed to characterize the mechanical properties of both, the fusion zone and the joints. It was shown that TWIP matrix composites with zirconia particles can be successfully brazed with Ni filler. With an optimized energy transfer function, the distortion of the butt joints can be minimized. After brazing with Ni-based filler, the brazing zone contains ≈ 35 to 50% brittle phases. During tensile tests, rupture took place within the brazing zone alongside the brittle phases. Nevertheless, the samples exhibited a maximum tensile strength of 358 MPa.

The use of electron-beam technology to produce bimetallic contacts for electrical plants

The process of producing compounds of VM-80 tungsten–copper alloy with BrX1Tsr chrome–zircon bronze using the methods of electron-beam brazing, surfacing, and welding is considered as applied to creating billets for producing bimetallic electrical contacts. The structures of the bimetallic contact and the main processes of electron-beam brazing, surfacing and welding of the specified materials are studied; the microstructure and mechanical properties of joints produced by the methods of electron-beam brazing and surfacing are investigated; and practical recommendations are given for the performance of further thermal treatment so as to improve the mechanical properties of obtained compounds. The results of this work may be of interest for specialists in the area of electrical-equipment design.

Electron beam brazing of Zr62Al13Ni7Cu18 bulk metallic glass with Ti metal

Electron beam brazing (EBB) of 2 mm thick Zr62Al13Ni7Cu18 bulk metallic glass (BMG) plate to Ti metal has successfully been accomplished by employing optimized electron beam brazing parameters and providing high cooling rate during solidification. The beam was irradiated 0.3 mm on the BMG side from the interface to avoid significant change in the chemical composition of weld metal in comparison to the base BMG. The welded joint was characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and X-ray radiography techniques. The welded joint was found to be very sound with no crystallization or defects around the interface. Finally, microhardness profile across the welded joint was determined indicating a little increase in the hardness of the weld metal in comparison to that of BMG.

Energy Density Distribution and Temperature Closed-Loop Control in Electron Beam Processing

Various electron beam (EB) processing methods such as EB brazing, surface modification, heat treatment, etching, evaporation coating and quick manufacture, etc. require that the energy distribution and processing temperature be controlled. In this study, the energy distribution control was realized by EB scanning trajectory pattern control, and the temperature control was realized by the combined use of fuzzy logic and PID control. These were integrated into one system. To obtain large deflection angle of EB, an external deflection coil was used. The scanning trajectory pattern was the synthesization of deflections of EB in X and Y directions, and each of the deflections was controlled by an analog. Because of high energy density of the EB, and consequently high sensitivity of weldment temperature to the beam current, closed-loop control of processing temperature is indispensable, which was realized in this paper. Satisfactory transient and steady-state specifications were obtained. The brazing of a specially designed specimen verified the effectiveness of the method.

Numerical Simulation of Temperature Field and Stress Field of Electron Beam Brazing Stainless Steel Radiator

Aiming at the radiator with tube-to-plate structure applied usually in aeroplane, a two-dimensional model for finite element analysis was established in this work. By ANSYS software, the temperature field and stress field of electron beam brazing (EBB) 1Cr18Ni9Ti stainless steel radiator by two kinds of process were numerically simulated. The calculated results of temperature field show, by the stage-by-stage heating process, the uniform temperature distribution of radiator faying face was obtained. The temperature of most regions is between 1042~1051°C, which is in the range of brazing temperature. The calculation results of stress field indicate, for radial residual stress, the obvious stress concentration region was found in faying face by direct-heating process; while there was no stress concentration in faying face by stage-by-stage heating process. For circumferential residual stress, compared the stage-by-stage heating process with direct-heating process, the peak value of tensile stress reduces by 11.2%. Compared circumferential residual stress with radial residual stress by two kinds of brazing process, the peak value of circumferential tensile stress is higher than radial tensile stress. So the dangerous position of faying face is along circle direction, namely, the heating direction of scanning electron beam. Consequently, the temperature difference between different positions in faying face must be controlled well during heating. The reduction of temperature difference can fall the peak value of tensile stress and improve the distribution of residual stress.

Scanning electron beam brazing of thin-wall capillary tube–sheet structure

This paper is aimed at research on brazing technological parameters of thin-wall capillary tube–sheet joints with vacuum scanning electron beam (VSEB) heating system, which is a full automatic closed-loop control system and can be used to program and generate any expected scanning tracks by computer virtual technique. As the new method is adopted, general brazing defects such as erosion, burning through, jam will be prevented effectively. Therefore various thin-wall tube–sheet structures can be brazed successfully, and welding quality and brazing productivity have been raised immensely.

Microstructure and Mechanical Property of Electron Beam Brazing and Vacuum Brazing Joints of Stainless Steel

By means of optical microscope(OM), scanning electron microscope(SEM), X-ray diffraction(XRD) and shear test, the microstructure and mechanical property of 1Cr18Ni9Ti stainless steel brazed joints with BNi-2 filler by electron beam brazing(EBB) and vacuum brazing(VB) are investigated respectively. The results show that, the microstructures of brazed joint with BNi-2 by EBB are mainly solid solutions of Ni. And the microstructures of brazed joint by VB are composed of two parts: one part is a solid solution of Ni, which lies adjacent to base metal; another part is chemical compound structures present in the centre zone of brazing seam. The shear strength of brazed joint by EBB is higher than that of by VB. This is closely related with the microstructures of brazed joint.

Investigation of contact phenomena at cubic boron nitride-filler metal interface during electron beam brazing

Abstract The physical and chemical processes which occur at the cubic boron nitride (CBN)-filler metal interface during electron beam brazing are investigated. Contact angles of wettability of multicomponent adhesion-active Cu-based alloys on CBN and steel are determined. The distribution of chemical elements at the CBN-brazing filler metal interface was investigated using an electron microscope and electron probe microanalyser. The titanium concentration is found to abruptly enhance at the interface as against the content of this element in a brazing filler metal, and Ti and Cu diffuse in a superhard material. A mutual diffusion of solid and liquid phase components results in the formation of a narrow transition layer 2–3 μ m thick that consists of titanium-boron compounds and solid solutions. A qualitative elemental composition is analysed for structure components at different brazing alloy zones. It is established that a phase containing up to 62 wt.% Ti can be formed near a CBN- brazing filler metal interface during an electron beam brazing.

Comparison of thick ETP and OF copper joints produced by electron beam, high‐power laser and traditional silver brazing

Synopsis As part of an extensive range of tests carried out by Ansaldo Ricerche to develop fabrication technology for a nuclear fusion reactor, some specific work has been done on the welding of thick copper electrical conductors. This has been done in order to offer the electrical engineering industry some valid alternatives to the traditional silver brazing system which is often employed, even although there are sometimes limits to its use. In these investigations, after a series of setting‐up tests, some joints were made by electron beam and high‐power laser welding of two types of 10 mm thick copper: ETP (electrolytic tough pitch) and OF (oxygen‐free). These joints were compared, by means of mechanical tests, electrical measurements, non‐destructive testing and metallographic examination, with similar joints welded by traditional silver brazing. The results show that the joints welded by electron beam and laser guarantee better mechanical strength properties and quality.

A laboratory technique for electron beam brazing

A laboratory technique for electron beam brazing