Improving Process Control in Electron Beam Welding Using the Enhanced Modified Faraday Cup

2008 ◽  
Vol 130 (4) ◽  
Author(s):  
T. A. Palmer ◽  
J. W. Elmer
Keyword(s):  
Electron Beam ◽  
Process Control ◽  
Diagnostic Tool ◽  
Electron Beam Welding ◽  
Lawrence Livermore National Laboratory ◽  
National Laboratory ◽  
Welding Parameters ◽  
Full Width ◽  
Faraday Cup ◽  
Beam Characteristics

Process control in electron beam welding is typically based on control of machine settings, such as accelerating voltage, beam current, focus coil current, and vacuum level. These settings, though important, provide little insight into the characteristics of the beam used to make the weld. With the enhanced modified Faraday cup (EMFC) diagnostic tool, these beam characteristics, including the peak power density, full width at half maximum, and full width at 1∕e2 values, can be quantified. The use of this diagnostic tool in an extended production run at Lawrence Livermore National Laboratory (LLNL) is described. Results show that machine performance, in terms of these measured beam characteristics, varies over time when the EMFC is not used to adjust the machine settings. Testing has shown that the variability of the beam characteristics can be measurably decreased with the use of the EMFC diagnostic tool. With the implementation of this diagnostic tool in the process control procedures, every electron beam weld, which encompassed approximately 90 welds over an 18month time frame, met all of the requirements defined in the weld process specification and passed all of the postweld quality control checks. The results also show that variations in each of the measured beam parameters can be controlled at levels below ±2.2%, which is smaller than the 5% tolerance band suggested by ASME for other welding parameters. Such an enhanced level of control allows product throughput to be increased by decreasing the number of rejected parts through the elimination of unexpected variations in beam characteristics. The benefits of integrating this diagnostic tool into future process control regimes are also discussed.

scholarly journals Characterization of a bright, tunable, ultrafast Compton scattering X-ray source

2004 ◽  
Vol 22 (3) ◽  
pp. 221-244 ◽  
Author(s):  
F.V. HARTEMANN ◽  
A.M. TREMAINE ◽  
S.G. ANDERSON ◽  
C.P.J. BARTY ◽  
S.M. BETTS ◽  
...  
Keyword(s):  
Electron Beam ◽  
Laser Pulse ◽  
Compton Scattering ◽  
Electron Beams ◽  
Lawrence Livermore National Laboratory ◽  
National Laboratory ◽  
X Rays ◽  
Full Width ◽  
Half Maximum ◽  
X Ray

The Compton scattering of a terawatt-class, femtosecond laser pulse by a high-brightness, relativistic electron beam has been demonstrated as a viable approach toward compact, tunable sources of bright, femtosecond, hard X-ray flashes. The main focus of this article is a detailed description of such a novel X-ray source, namely the PLEIADES (Picosecond Laser–Electron Inter-Action for the Dynamical Evaluation of Structures) facility at Lawrence Livermore National Laboratory. PLEIADES has produced first light at 70 keV, thus enabling critical applications, such as advanced backlighting for the National Ignition Facility andin situtime-resolved studies of high-Zmaterials. To date, the electron beam has been focused down to σx= σy= 27 μm rms, at 57 MeV, with 266 pC of charge, a relative energy spread of 0.2%, a normalized horizontal emittance of 3.5 mm·mrad, a normalized vertical emittance of 11 mm·mrad, and a duration of 3 ps rms. The compressed laser pulse energy at focus is 480 mJ, the pulse duration 54 fs Intensity Full Width at Half-Maximum (IFWHM), and the 1/e2radius 36 μm. Initial X rays produced by head-on collisions between the laser and electron beams at a repetition rate of 10 Hz were captured with a cooled CCD using a CsI scintillator; the peak photon energy was approximately 78 keV, and the observed angular distribution was found to agree very well with three-dimensional codes. The current X-ray dose is 3 × 106photons per pulse, and the inferred peak brightness exceeds 1015photons/(mm2× mrad2× s × 0.1% bandwidth). Spectral measurements using calibrated foils of variable thickness are consistent with theory. Measurements of the X-ray dose as a function of the delay between the laser and electron beams show a 24-ps full width at half maximum (FWHM) window, as predicted by theory, in contrast with a measured timing jitter of 1.2 ps, which contributes to the stability of the source. In addition,K-edge radiographs of a Ta foil obtained at different electron beam energies clearly demonstrate the γ2-tunability of the source and show very good agreement with the theoretical divergence-angle dependence of the X-ray spectrum. Finally, electron bunch shortening experiments using velocity compression have also been performed and durations as short as 300 fs rms have been observed using coherent transition radiation; the corresponding inferred peak X-ray flux approaches 1019photons/s.

scholarly journals Development of Welding P92 Pipes Using the Reduced Pressure Electron Beam Welding Process for a Study of Creep Performance

2014 ◽  
Author(s):  
Nick Bagshaw ◽  
Chris Punshon ◽  
John Rothwell
Keyword(s):  
Electron Beam ◽  
Heat Input ◽  
Power Plants ◽  
Electron Beam Welding ◽  
Welding Process ◽  
Welding Parameters ◽  
Pipe Material ◽  
Reduced Pressure ◽  
Type Iv ◽  
Type Iv Cracking

Boiler and steam piping components in power plants are fabricated using creep strength enhanced ferritic (CSEF) steels, which often operate at temperatures above 550°C. Modification of alloy content within these steels has produced better creep performance and higher operating temperatures, which increases the process efficiency of power plants. The improved materials, however, are susceptible to type IV cracking at the welded regions. A better understanding of type IV cracking in these materials is required and is the basis of the Technology Strategy Board (TSB) UK funded VALID (Verified Approaches to Life Management & Improved Design of High Temperature Steels for Advanced Steam Plants) project. In order to study the relationship between creep performance and heat input during welding, several welds with varying amounts of heat input and resultant HAZ widths were produced using the electron beam welding process. The welding parameters were developed with the aid of weld process modeling using the finite element (FE) method, in which the welding parameters were optimized to produce low, medium and high heat input welds. In this paper, the modeling approach and the development of electron beam welds in ASTM A387 grade P92 pipe material are presented. Creep specimens were extracted from the welded pipes and testing is ongoing. The authors acknowledge the VALID project partners, contributors and funding body: Air Liquide, Metrode, Polysoude, E.ON New Build & Technology Ltd, UKE.ON, Doosan, Centrica Energy, SSE, Tenaris, TU Chemnitz, The University of Nottingham, The Open University and UK TSB. Paper published with permission.

Influence of Electron Beam Technological Movements on Aluminium Alloy AW2099 Welded Joints Properties

2020 ◽  
Vol 994 ◽  
pp. 36-43
Author(s):  
Ján Urminský ◽  
Milan Marônek ◽  
Jozef Bárta ◽  
Michaela Lopatková ◽  
Róbert Hrušecký
Keyword(s):  
Electron Beam ◽  
Welded Joints ◽  
Electron Beam Welding ◽  
Welding Current ◽  
Welding Parameters ◽  
Porosity Formation ◽  
Surface Appearance ◽  
Current Focusing ◽  
Acceleration Voltage ◽  
Beam Oscillation

The electron beam welding (EBW) parameters have significant influence on weld surface appearance and porosity formation. Besides basic welding parameters, such as acceleration voltage, welding current, focusing current and welding speed, the beam oscillation during EBW plays an important role in weld metal formation and directly impacts the final welded joints properties. The influence of technological movements during EBW on the properties of aluminium-lithium alloy welded joints was studied. The same frequency and different amplitude as well as same amplitude and different frequency were chosen. The other welding parameters were constant.

scholarly journals The importance of EBIT data for Z-pinch plasma diagnostics

2008 ◽  
Vol 86 (1) ◽  
pp. 267-276 ◽  
Author(s):  
A S Safronova ◽  
V L Kantsyrev ◽  
P Neill ◽  
U I Safronova ◽  
D A Fedin ◽  
...  
Keyword(s):  
Electron Beam ◽  
Lawrence Livermore National Laboratory ◽  
National Laboratory ◽  
Theoretical Models ◽  
High Energy ◽  
High Energy Density ◽  
Strong Electron ◽  
Model Calculations ◽  
X Ray ◽  
Z Pinch

The results from the last six years of X-ray spectroscopy and spectropolarimetry of high-energy density Z-pinch plasmas complemented by experiments with the electron beam ion trap (EBIT) at the Lawrence Livermore National Laboratory (LLNL) are presented. The two topics discussed are the development of M-shell X-ray W spectroscopic diagnostics and K-shell Ti spectropolarimetry of Z-pinch plasmas. The main focus is on radiation from a specific load configuration called an “X-pinch”. In this work the study of X-pinches with tungsten wires combined with wires from other, lower Z materials is reported. Utilizing data produced with the LLNL EBIT at different energies of the electron beam the theoretical prediction of line positions and intensity of M-shell W spectra were tested and calibrated. Polarization-sensitive X-pinch experiments at the University of Nevada, Reno (UNR) provide experimental evidence for the existence of strong electron beams in Ti and Mo X-pinch plasmas and motivate the development of X-ray spectropolarimetry of Z-pinch plasmas. This diagnostic is based on the measurement of spectra recorded simultaneously by two spectrometers with different sensitivity to the linear polarization of the observed lines and compared with theoretical models of polarization-dependent spectra. Polarization-dependent K-shell spectra from Ti X-pinches are presented and compared with model calculations and with spectra generated by a quasi-Maxwellian electron beam at the LLNL EBIT-II electron beam ion trap.PACS Nos.: 32.30.Rj, 52.58.Lq, 52.70.La

scholarly journals Effect of Electron Beam Welding Parameters on Temperature and Stress Field of AISI P20 Tool Steel in Vacuum Roll-cladding Process

2021 ◽  
Author(s):  
lanyu mao ◽  
Zongan Luo ◽  
Yingying Feng ◽  
Xiaoming Zhang
Keyword(s):  
Electron Beam ◽  
Stress Field ◽  
Tool Steel ◽  
Welding Speed ◽  
Electron Beam Welding ◽  
Welding Process ◽  
Welding Current ◽  
Temperature Fields ◽  
Welding Parameters ◽  
Aisi P20

Abstract Vacuum roll-cladding (VRC) is an effective method to produce high quality ultra-heavy AISI P20 plate steel. In the process of VRC, reasonable welding process of electron beam welding (EBW) can significantly avoid welding cracks and reduce the cost. In this paper, the electron beam welding process of AISI P20 tool steel was simulated by using a combined heat source model based on finite element method, and the temperature field and stress field under different welding parameters were studied respectively . The results showed that welding parameters have a greater effect on weld penetration than that of weld width, which making the aspect ratio increases with the increase of welding current, and decrease with the increase of welding speed. The weld morphologies were consistent with those of the modeling and the measured thermal heat curves were good agreement with those of simulated, which was verified the feasibility and effectiveness of temperature fields. The results of stress fields under different welding parameters indicat ed that lower welding speed and higher welding current resulting in lower residual stress at welded joint, which means lower risk of cracking after EBW. The results of this study have been successfully applied to industrial production.

Microstructural Evolution and Mechanical Properties of Electron Beam–Welded Ti70/TA5 Dissimilar Joint

2020 ◽  
Vol 143 (2) ◽  
Author(s):  
Donghui Wang ◽  
Shaogang Wang ◽  
Wen Zhang
Keyword(s):  
Mechanical Properties ◽  
Electron Beam ◽  
Electron Beam Welding ◽  
Dissimilar Joint ◽  
Welding Parameters ◽  
Tem Analysis ◽  
Β Phase ◽  
Α Phase ◽  
Joint Fracture ◽  
Phase Transmission

Abstract The dissimilar titanium alloys Ti70/TA5 are welded by using electron beam welding. The microstructure and mechanical properties of the welded joints are systematically investigated, and the welding parameters are optimized. Results show that the fusion zone (FZ) is mainly α’ martensite, and the heat-affected zone (HAZ) in the Ti70 side consists of fine α’ martensite, residual α phase, and original β phase, while the HAZ in the TA5 side is composed of coarser α phase, serrated and acicular α phase. Transmission electron microscope (TEM) analysis demonstrates that the martensite in the FZ presents the lath-like morphology. There are high-density dislocations within martensite, which has a certain orientation relationship with the β phase. Under the appropriate welding procedure, the tensile strength of the dissimilar joint is close to that of the TA5 base metal. The joint fracture dominantly presents the characteristic of ductile fracture. During welding, electron beam scanning is beneficial to improving the solidification of molten pool and grain refinement; thus, the mechanical property of the welded joint is increased to a certain extent.

A HIGH-DENSITY ELECTRON BEAM AND QUAD-SCAN MEASUREMENTS AT PLEIADES THOMSON X-RAY SOURCE

2007 ◽  
Vol 22 (23) ◽  
pp. 4317-4323
Author(s):  
J. K. LIM ◽  
J. B. ROSENZWEIG ◽  
S. G. ANDERSON ◽  
A. M. TREMAINE
Keyword(s):  
Electron Beam ◽  
Optical Transition ◽  
Beam Quality ◽  
Lawrence Livermore National Laboratory ◽  
National Laboratory ◽  
High Density ◽  
Interaction Point ◽  
Beam Spot ◽  
X Ray ◽  
Parameter Values

A recent development of the photo-cathode injector technology has greatly enhanced the beam quality necessary for the creation of high density/high brightness electron beam sources. In the Thomson backscattering x-ray experiment, there is an immense need for under 20 micron electron beam spot at the interaction point with a high-intensity laser in order to produce a large x-ray flux. This has been demonstrated successfully at PLEIADES in Lawrence Livermore National Laboratory. For this Thomson backscattering experiment, we employed an asymmetric triplet, high remanence permanent-magnet quads to produce smaller electron beams. Utilizing highly efficient optical transition radiation (OTR) beam spot imaging technique and varying electron focal spot sizes enabled a quadrupole scan at the interaction zone. Comparisons between Twiss parameters obtained upstream to those parameter values deduced from PMQ scan will be presented in this report.

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