Electron-beam generator produces high quality welds without vaporization by relying on the mobility and hydrodynamic properties of the material in its liquid phase. The power density of the beam is relative to the speed of the workpiece, producing an inclined weld-front

Schumacher, B.

English

NASA Technical Reports Server

June 1970
	
Brief 70-10127 
NASA TECH BRIEF 
NASA Tech Briefs announce new technology derived from the U .S. space program. They are issued to encourage commercial 
application. Tech-Briefs are available on a subscription basis from the Clearinghouse for Federal Scientific and Technical 
Information, Springfield, Virginia 22151. Requests for individual copies 'or questions relating to the Tech Brief program may 
be directed to the Technology Utilization Division, NASA, Code UT, Washington, D.C. 20546. 
Improved Electron-Beam Welding Technique 
Workpiece 
Elongated Beam 
Formation of an Inclined Weld-Front
with an Electron Beam 
In electron-beam welding, the projected beam and 
the workpiece are moved relative to each other to pro-
duce the welded joint. Either the beam is moved along 
a stationary workpiece or the workpiece is moved 
under a stationary beam. An electron beam, even of 
very high energy density, can penetrate the workpiece 
only a very short distance—of the order of several hun-
dred microns. To produce a joint of* appreciable pene-
tration, the usual practice has been to maintain the 
beam at a sufficiently high energy density to vaporize 
material along the joint being welded. The beam then 
penetrates through the vapor and produces a channel 
filled with vapor which becomes liquid and solidifies 
after the beam has movedto a succeeding position. A 
beam channel or hole is formed at the start of the 
welding seam and for this reason, the process has been 
called the "key-hole" process. The "key-hole" proc-
ess has the disadvantages that it requires high beam 
energy and high energy density. The energy density 
must be sufficient not only to melt the material at the 
joint but also to vaporize it. While the power cost to 
achieve this high energy must be considered, a more 
important factor is that the high energy, which the 
incremental parts of the joint receive from the beam, 
produces imperfections in the weld by reason of vari-
ations in beam power and small in homogeneities in the 
work. In fact, it has been realized that in order to pro-
duce high-quality welded seams, a delicate balance 
must be maintained between beam-power input and 
the melting vaporization rate of the work, i.e., welding 
speed. 
It has been demonstrated that by relying on the mo-
bility and the hydrodynamic properties of the material 
when it is in a liquid phase, an electron beam generator 
can be used to produce high quality welds without 
vaporizing the workpiece material; the liquid phase 
state permits more beam energy to be transferred to 
the weld-front. The welding is accomplished with the 
electron beam impinging on the workpiece and the 
beam and workpiece moving relative to each other. 
The power density of the beam, relative to the speed 
of the workpiece, is such that the material is melted 
but not vaporized; thus, an inclined weld-front, shown 
in the figure, is produced. The angle of inclination of 
(continued overleaf) 
Now
This document was prepared under the sponsorship of the National	 Government assumes any liability resulting from the use of the 
Aeronautics and Space Administration. Neither the United States	 information contained in this document, or warrants that such use 
Government nor any person acting on behalf of the United States
	 will be free from privately ownedrights.
https://ntrs.nasa.gov/search.jsp?R=19700000123 2020-03-17T00:25:20+00:00Z
the weld-front depends on the diameter of the beam 
on the workpiece and the desired depth or penetration 
of the weld (usually the depth is 100% penetration). At 
the start of a weld, there is slight vaporization of the 
workpiece and at the end, the weld terminates in a 
sloped crater (if stopped before the end of the metal 
part is reached) or in a sloped notch. At successive 
regions of the melt-iron, the liquid work material 
moves out of the path of the beam so that the beam 
progressively impinges on unmelted material. 
The electron beam may also be swept back and forth 
along the direction of movement of the workpiece by 
applying an oscillatory voltage to the control coils. 
This produces, in effect, an elongated beam with a 
substantially higher angle of inclination, a, than for 
an axially symmetric beam. 
Several hundred welds were made in the described 
manner to improve this weld technique. The welds 
were made with the electron beam generator set to pro-
ject an axially symmetric beam pattern on the work-
piece. The beam voltage was set at 150 kV and the 
beam power was at different magnitudes (3, 4, 5 and
7 kW) for different sets of welds. The beam power was 
measured with a Faraday cup; scatter losses, created 
by gas in the beam-transfer column, were found not 
to affect the beam power which produced the weld. 
Most welds were of the bead-through-plate variety 
made on 2219-T87 aluminum. 
Note: 
Requests for further information may be directed to: 
Technology Utilization Officer 
Marshall Space Flight Center 
Huntsville, Alabama 35812 
Reference: B70-10127 
Patent status: 
Inquiries about obtaining rights for the commer-
cial use of this invention may be made to NASA, Code 
GP, Washington, D.C. 20546. 
Source: B. Schumacher of
Westinghouse Electric Corp. 
under contract to
Marshall Space Flight Center 
(MFS-207 14)
. 
Brief 70-10127	 Category 08


Improved electron-beam welding technique

Abstract

Similar works

Full text

Available Versions

NASA Technical Reports Server