Three-Dimensional Electron-Beam Deflection and Missed Joint in Welding Dissimilar Metals

1997 ◽  
Vol 119 (4) ◽  
pp. 832-839 ◽  
Author(s):  
P. S. Wei ◽  
F. K. Chung
Keyword(s):  
Electron Beam ◽  
Electrical Contact ◽  
Three Dimensional ◽  
Electron Gun ◽  
Beam Deflection ◽  
Beam Power ◽  
Dissimilar Metals ◽  
Electrical Contact Resistance ◽  
Paraboloid Of Revolution

Three-dimensional deflection of the electron beam resulting in a missed joint due to thermoelectric magnetism generated while welding dissimilar metals is systematically investigated. The incident energy rate distribution is assumed to be Gaussian and the deep and narrow welding cavity induced is idealized as a paraboloid of revolution. With a three-dimensional analytical solution for the temperature and by solving Maxwell’s electromagnetic equations, thermoelectric currents, magnetic flux densities, and deflections of the beam are found. The predictions agree with available experimental data. The results find that missed joints can be reduced by increasing the dimensionless accelerating voltage-to-Seebeck e.m.f. parameter, Peclet number, and effective electrical contact resistance parameter, and decreasing dimensionless beam power, magnetic permeabilities, and electrical conductivity ratio between metals 1 and 2. Tilting workpieces and shifting the electron gun from the joint line are also feasible. A three-dimensional analysis is required for a successful determination of beam deflection.

Electron Beam Deflection When Welding Dissimilar Metals

1990 ◽  
Vol 112 (3) ◽  
pp. 714-720 ◽  
Author(s):  
P. S. Wei ◽  
T. W. Lii
Keyword(s):  
Electron Beam ◽  
Incident Angle ◽  
Electrical Contact ◽  
Beam Deflection ◽  
Beam Power ◽  
Dissimilar Metals ◽  
Electrical Contact Resistance ◽  
Energy Beam ◽  
Relative Magnetic Permeability ◽  
The Difference

High-intensity electron beam deflection due to thermoelectric magnetism generated during the welding of dissimilar metals is systematically and analytically investigated. A simple thermoelectric model is proposed and the temperature field, penetration depth of the fusion zone, magnetic field, and motion of an electron are determined. Deviation of the fused zone from a joint is affected by the incident angle of the energy beam, the difference in Seebeck coefficients of workpieces, relative magnetic permeability, beam power, welding speed, thermal and electrical conductivities, and the effective electrical contact resistance. Their effects are clearly interpreted in this study. Analytical results for the deviation of the fused zone from the joint between the materials to be welded show good agreement with available experimental data.

Molten Region around the Cavity Generated by a Moving Electron Beam

2011 ◽  
Vol 421 ◽  
pp. 169-172
Author(s):  
Yu Hsiang Tsai ◽  
Ching Yen Ho
Keyword(s):  
Electron Beam ◽  
Three Dimensional ◽  
Source Model ◽  
Beam Power ◽  
Image Method ◽  
Adiabatic Condition ◽  
Paraboloid Of Revolution ◽  
Line Source Model ◽  
Infinite Temperature ◽  
Molten Region

In this paper analytical predictions of the molten region around the cavity produced by a moving electron beam are provided. A three-dimensional analytical model is used to predict the molten and heat-affected regions surrounding a paraboloid of revolution-shaped cavity. This work avoids the defect of the infinite temperature at the cavity base for the line-source model. Introducing a new image method, an analytical solution is provided by satisfying exactly the adiabatic condition at the top surface. The molten region is governed by dimensionless parameters related to beam power per unit penetration and the depth and shape of the cavity in this work. A three-dimensional molten region is computed and presented in this paper. The effect of beam power per unit penetration on the molten region is also discussed.

Shape of Fusion Zone for the Welding Keyhole Induced by an Electron Beam

2013 ◽  
Vol 773-774 ◽  
pp. 812-817
Author(s):  
Ching Yen Ho ◽  
Yu Hsiang Tsai
Keyword(s):  
Electron Beam ◽  
Fusion Zone ◽  
Three Dimensional ◽  
Source Model ◽  
Beam Power ◽  
Image Method ◽  
Adiabatic Condition ◽  
Paraboloid Of Revolution ◽  
Dimensional Shape ◽  
Three Dimensional Shape

In this paper analytical predictions of the fusion zone shapes around the welding cavity produced by a moving electron beam are provided. A three-dimensional analytical model in the molten and heat-affected regions surrounding a paraboloid of revolution-shaped cavity is used to predict the shapes of the fusion zones. This work avoids the defect of the infinite temperature at the cavity base for the line-source model. Introducing a new image method, a new analytical solution is provided by satisfying exactly the adiabatic condition at the top surface. The shape of a fusion zone is governed by dimensionless parameters related to beam power per unit penetration, and the depth and shape of the cavity in this work. A three-dimensional shape of fusion zone is computed and presented in this paper. The effect of beam power per unit penetration on the shape of fusion is also discussed.

Point-Cathode Electron Gun Using Electron-Beam Bombardment for Cathode Tip Heating

1990 ◽  
Vol 48 (1) ◽  
pp. 198-199
Author(s):  
Ryo Iiyoshi ◽  
Susumu Maruse ◽  
Hideo Takematsu
Keyword(s):  
Electron Beam ◽  
Tungsten Wire ◽  
Local Heating ◽  
Electron Gun ◽  
Original Position ◽  
Beam Power ◽  
Radius Of Curvature ◽  
High Brightness ◽  
Beam Focusing ◽  
Time Operation

Point cathode electron gun with high brightness and long cathode life has been developed. In this gun, a straightened tungsten wire is used as the point cathode, and the tip is locally heated to higher temperatures by electron beam bombardment. The high brightness operation and some findings on the local heating are presented.Gun construction is shown in Fig.l. Small heater assembly (annular electron gun: 5 keV, 1 mA) is set inside the Wehnelt electrode. The heater provides a disk-shaped bombarding electron beam focusing onto the cathode tip. The cathode is the tungsten wire of 0.1 mm in diameter. The tip temperature is raised to the melting point (3,650 K) at the beam power of 5 W, without any serious problem of secondary electrons for the gun operation. Figure 2 shows the cathode after a long time operation at high temperatures, or high brightnesses. Evaporation occurs at the tip, and the tip part retains a conical shape. The cathode can be used for a long period of time. The tip apex keeps the radius of curvature of 0.4 μm at 3,000 K and 0.3 μm at 3,200 K. The gun provides the stable beam up to the brightness of 6.4×106 A/cm2sr (3,150 K) at the accelerating voltage of 50 kV. At 3.4×l06 A/cm2sr (3,040 K), the tip recedes at a slow rate (26 μm/h), so that the effect can be offset by adjusting the Wehnelt bias voltage. The tip temperature is decreased as the tip moves out from the original position, but it can be kept at constant by increasing the bombarding beam power. This way of operation is possible for 10 h. A stepwise movement of the cathode is enough for the subsequent operation. Higher brightness operations with the rapid receding rates of the tip may be improved by a continuous movement of the wire cathode during the operations. Figure 3 shows the relation between the beam brightness, the tip receding rate by evaporation (αis the half-angle of the tip cone), and the cathode life per unit length, as a function of the cathode temperature. The working life of the point cathode is greatly improved by the local heating.

scholarly journals Photon flux determination of a liquid-metal jet X-ray source by means of photon scattering

2019 ◽  
Vol 34 (7) ◽  
pp. 1497-1502 ◽  
Author(s):  
Malte Wansleben ◽  
Claudia Zech ◽  
Cornelia Streeck ◽  
Jan Weser ◽  
Christoph Genzel ◽  
...  
Keyword(s):  
Electron Beam ◽  
Liquid Metal ◽  
Power Density ◽  
Photon Flux ◽  
Beam Power ◽  
Photon Scattering ◽  
X Ray ◽  
Metal Anode ◽  
Metal Jet

Liquid-metal jet X-ray sources promise to deliver high photon fluxes, which are unprecedented for laboratory based X-ray sources, because the regenerating liquid-metal anode is less sensitive to damage caused by an increased electron beam power density.

scholarly journals Determination of Nonconductive Coating Thickness Using Electrical Contact Conductance and Surface Profile

Coatings ◽  
2018 ◽  
Vol 8 (9) ◽  
pp. 310 ◽  
Author(s):  
Kyungmok Kim ◽  
Jaewook Lee
Keyword(s):  
Coating Thickness ◽  
Electrical Contact ◽  
Surface Profile ◽  
Steel Specimen ◽  
Vertical Displacement ◽  
Relative Displacement ◽  
Optical Microscope ◽  
Electrical Contact Resistance ◽  
Contact Conductance

This paper describes a method to determine the thickness of a nonconductive coating by identifying the transition of material by a change in electrical properties. A slide-hold-slide test was conducted with a worn specimen including an electrodeposited coating layer. Relative displacement was imposed between a metallic stylus tip and a worn steel specimen. After an initial sliding, the tip was held for a certain time to measure electrical contact resistance. During the test, the vertical displacement of the stylus tip was also recorded to draw a surface profile of the worn specimen. Coating thickness on the specimen was determined with a surface profile at the transition of electrical contact conductance. Optical cross-section measurement of the specimen was applied to identify actual coating thickness. Measured results reveal that calculated coating thicknesses are in good agreement with measured values by an optical microscope. The proposed method allows determination of both nonconductive coating thickness and surface profile in a single measurement.

Line-Source Processing of SOI Structures with Laser and Electron Beam

1984 ◽  
Vol 33 ◽  
Author(s):  
Leslie J. Palkuti ◽  
Chan-Sui pang
Keyword(s):  
Electron Beam ◽  
Single Crystal ◽  
Three Dimensional ◽  
Process Window ◽  
Beam Power ◽  
Temperature Cycle ◽  
Halogen Lamp ◽  
Substrate Heating ◽  
Aspect Ratios ◽  
Laser Systems

ABSTRACTLine-shaped laser and electron beams in combination with halogen-lamp substrate heating were used to fabricate single-crystal SOI films. Electron-beam and laser systems were developed to achieve a minimum beam cross section of 10–100 microns and aspect ratios up to 70. Unseeded SOI films were fabricated with a (100) textured single-crystal structure. Seeded films were recrystallized with 20 × 80-micron single crystal islands with no low-angle grain boundaries. A process window of 1 to 10 percent in electron-beam power was measured. Single-crystal films were obtained at a line-scan velocity up to 2 cm/s suggesting a potential throughput of about 100 wafers per hour. The high scan velocity allows for minimizing the high-temperature cycle to under 30 seconds that the wafer is exposed to during recrystallization. This short temperture cycle is compatible with the fabrication of three dimensional devices, since unwanted diffusion and substrate damage are minimized.

Scanning system development and digital beam control method for electron beam selective melting

2015 ◽  
Vol 21 (3) ◽  
pp. 313-321 ◽  
Author(s):  
Chao Guo ◽  
Jing Zhang ◽  
Jun Zhang ◽  
Wenjun Ge ◽  
Bo Yao ◽  
...  
Keyword(s):  
Electron Beam ◽  
Large Deflection ◽  
Control Method ◽  
Three Dimensional ◽  
Beam Deflection ◽  
Scanning System ◽  
Content Type ◽  
Metal Parts ◽  
Digital Scanning ◽  
Electron Beam Selective Melting

Purpose – The purpose of this paper is to correct the beam deflection errors and beam defocus by using a digital scanning system. Electron beam selective melting (EBSM) is an additive manufacturing technology for metal parts. Beam deflection errors and beam defocus at large deflection angles would greatly influence the accuracy of the built parts. Design/methodology/approach – The 200 × 200 mm2 scanning area of the electron beam is discretized into 1001 × 1001 points arranged in array, based on which a digital scanning system is developed. To correct the deflection errors, the electron beam scans a 41 × 41 testing grid, and the corrective algorithm is based on the bilinear transformation from the grid points’ nominal coordinates to their measured coordinates. The beam defocus is corrected by a dynamic focusing method. A three-dimensional testing part is built with and without using the corrective algorithm, and their accuracies are quantitatively compared. Findings – The testing grid scanning result shows that the accuracy of the corrected beam deflection system is better than ± 0.2 mm and beam defocus at large deflection angles is eliminated visibly. The testing part built with using the corrective algorithm is of greater accuracy than the one built without using it. Originality/value – Benefiting from the digital beam control method, the model-to-part accuracy of the system is effectively improved. The digital scanning system is feasible in rapid manufacturing large and complex three-dimensional metal parts.

scholarly journals Моделирование электронно-оптических систем со сходящимся ленточным пучком для лампы бегущей волны терагерцевого диапазона частот

2018 ◽  
Vol 44 (17) ◽  
pp. 78
Author(s):  
А.А. Бурцев ◽  
А.В. Данилушкин
Keyword(s):  
Electron Beam ◽  
Cross Section ◽  
Three Dimensional ◽  
Pulse Mode ◽  
Electron Gun ◽  
Three Dimensional Model ◽  
Collector Current ◽  
Current Voltage ◽  
Beam Thickness ◽  
Sheet Electron Beam

AbstractA converging sheet electron beam with a cross section of 0.05 × 2 mm and current density of 200 A/cm^2, which is formed by an electron gun, is modeled using the synthesis and analysis methods at the condition of magnetic shielding of the cathode. The deformation in the cross section of the beam in the focusing magnetic field is analyzed based on a computer three-dimensional model of an electron optical system with a sheet electron beam. The current-voltage characteristic of an electron gun is studied experimentally in the pulse mode. A collector current of 200 mA is obtained with the beam thickness being 70 μm.

Fusion Zone Shapes in Electron-Beam Welding Dissimilar Metals

2000 ◽  
Vol 122 (3) ◽  
pp. 626-631 ◽  
Author(s):  
P. S. Wei ◽  
Y. K. Kuo ◽  
J. S. Ku
Keyword(s):  
Electron Beam ◽  
Fusion Zone ◽  
Electron Beam Welding ◽  
Beam Power ◽  
Strong Mixing ◽  
Width Ratio ◽  
Dissimilar Metals ◽  
Measured Concentration ◽  
Joint Plane ◽  
The Difference

Experiments on welding dissimilar metals, such as aluminum or copper to iron with an electron-beam welder, are conducted. It is found that the observed depth-to-width ratio of the fusion zone in aluminum can be greater than unity while that in iron is around unity. The former is attributed to the formation of a cavity resulting from a high vapor pressure. The difference in depths increases with beam power. The observed depth-to-width ratios of fusion zones in welding copper to iron can be greater than unity. A unique maximum depth is near the joint plane, as a result of strong convective mixing and high incident flux, even though the melting temperatures are different. Strong mixing is confirmed by measured concentration profiles across the fusion zones of dissimilar metals. To a first approximation fusion zone depths with depth-to-width ratios greater than or identical to unity are determined from scale analyses of heat conduction equations in welding the same metals with a high and low-power-density beam, respectively. The propositions are verified by experimental results. [S0022-1481(00)00103-1]

Sign in / Sign up

Export Citation Format

Share Document