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Патент USA US2405673

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Aug. 13, 1946.
E. B. SCHERL
2,405,673
ELECTRIC WELDING
Filed Jan. 20, 1944
ATTORNEY
Patented Aug. 13, 1946
/
UNITED STATES
_ 2,405,673
PATENT OFFICE
2,405,673
ELECTRIC WELDING
Egon‘ B. Scherl, New York, N. Y., assignor to The
Linde Air Products Company, a corporation of
Ohio
Application January 20, 1944, Serial No. 518,915
1
3Claims. '(Cl. 219-10)
This invention relates to the art of electric
welding, and pertains more particularly to im
provements in those methods of electric welding
2
Butt welding of high strength steel by de
positing molten electrode metal at the welding
seam involves the problems mentioned above,
in which metal from an electrode is melted and
and the problems are particularly acute if the
deposited upon one or more metal workpieces to 5 workpieces are of heavy section, as is the case,
form a Joint or a metal overlay.
'
for instance, in welding heavy armor plate.
To form an adequate bond between the de
In order to take full advantage of the plate
posited metal and the workpiece it is necessary
strength‘, the weld metal should be equal in
that some metal of the workpiece be melted and
strength to the plate, and many alloy steel elec
coalesced with molten electrode metal. The high 10 trode compositions have been devised to accom
temperatures attained in electric welding assure
plish this end. Welds prepared with most of
considerable melting or "penetration” of the
these special electrodes are more frequently prone
workpiece, the extent of such penetration ‘being ‘to cracking than are, for example, those made
‘ greatest in those methods which achieve rapid
with mild steel. Probably, this is a result of the
welding speeds through the use of heavy welding 15 ?ne-grained character of the weld metal in the
currents.
alloy steel deposits, which is likely to produce
For some purposes, for instance the joining of
high contraction stresses. The cracks usually
mild steel workpieces, deep penetration of the
occur in a martensitic zone immediately adjacent
workpiece and thorough intermingling of molten
to the face of the weld deposit.
electrode metal with the molten workpiece metal 20 Preheating of the workpieces mitigates to some
is desirable as it assures a clean, sound weld
extent this susceptibility to cracking, as does the
deposit substantially homogeneous in chemical
practice of using a large-diameter electrode with
and-physical properties with the unmelted por
a heavy current to rapidly lay down a large
tions of the workpiece. Thus, in the welding
bead. Such measures are not always practicable
method described for instance in Patent 2,043,960,
nor entirely successful, and others have been
which comprises depositing metal from a bare
sought. For instance, considerable success in
electrode carrying a relatively heavy current and '
avoiding cracks has been achieved by the use of
blanketing the end of the electrode under a deep
electrodes of such composition that the metal
layer of- granular mineral-like material, the
in the fused zone of the weld is, upon solidi?ca
weight ratio of melted workpiece metal to meltedv 30 tion, austenitic in character and therefore in
electrode metal is ordinarily between‘ 1:1 and
herently ductile. In choosing the electrode com
2:1 and may be higher.
'
position, dilution by melted metal of the work
But it is not always advantageous to penetrate
piece must be carefully considered to insure the
the workpiece deeply.- The heat effects of a rel
proper structural nature of the weld. It is ap
atively large mass of molten ‘metal upon the un 35 parent that such dilution is wasteful of relatively
melted metal in areas adjacent the weld may be
expensive alloying ingredients such‘ as chromium,
undesirable, leading to undue softening or undue
nickel, and manganese, and if very great may
hardening and in the latter case even to em
require the use of such highly alloyed electrode
brittlement and cracking. Such embrittlement
materials that the problem of fabricating the
and ‘cracking is most likely to ‘be encountered 40 electrodes becomes very difficult and even im
when. welding heavy plates of high carbon al~
practically expensive. No ready method has
loyed steel.
heretofore
been found to reduce the dilution to
In some/welding operations use is made of an
a very low proportion. It is the principal object
electrode fcomposition materially different from
that of the workpiece. In such instances, a high 45 of this invention to provide a method to reduce
the dilution of electrode metal by workpiece
ratio of melted workpiece to melted electrode
metal. Another object is a method to decrease
greatly dilutes the deposit, thereby counteract
the penetration of a steel workpiece during elec
in: to a degree the desired effects of the electrode
tric welding.
composition. This problem is encountered, for
In its simplest and broadest form the inven
instance, in the art of depositing on a steel ‘base 50
a protective overlay of non-ferrous metal or
tion is a method which comprises applying to a
highly alloyed ferrous metal which has relatively
metal welding electrode heat'in addition to that
greater resistance to wear or / chemical attack
or both; but it is also encountered in numerous
other arts.
derived from the welding current. The addi
tional heat may be derived from electric currents
55 induced or conducted into the electrode or‘ from
2,405,053
3
4
the cross-section areas of portions of the weld
(fused metal) above and below the plate surface
any other, appropriate source such as a 833
?ame.~
were measured with a planimeter, with the re
In the accompanying drawing:
Fig. 1 is an elevation, partly schematic and
partly in section, of a typical apparatus suitable
for the practice of the method of this invention;
Fig. 2 shows, partly schematically, a modi?ed
form of part of such apparatus;
sults listed in the table.
-
Test
Volume of Volume of
Total area Haiti's {gale electrode
Current [used metal,
late
sq. inch
81)‘1' inc'h
Fig. 3 shows, partly ‘schematically, another
-modi?ed form of part of the apparatus oi! Fig. 10
1, and
"
.
..
plate
metal in
metal in
weld,
per cent
weld,
per cent
Ampere:
1 .... -.
800
1.09
‘0.37
34
Fig. 4 is a cross section of a steel workpiece
2 ____ __
500
0. 41
0. 19
45
55
containing deposits made, respectively, without
3 .... ..
500
0.40
'
0.31
78
22
66
and with preheated electrodes.
Thus, it can be seen that by the method of
Referring to the Figs. 1 to 3, in a preferred 15
form the invention comprises applying additional > the invention (Test 3), at 500 amperes the de
posit above the plate was far greater than at
heat to a bare metal electrode I0, for example
the same amperage without electrode preheat
vof austenitic steel, while the end of such elec
(Test 2) and nearly as great as at 800 amperes
trode is melted and deposited under a heavy
blanket ll of comminuted mineral-like material 20 without preheat (Test 1). Even more impor
tantly, the deposit made according to the inven
at the seam between steel plates l2, I3, for ex~
tion contained 3.5 times as much electrode metal
ample alloyed high-carbon steel plates such as
as plate metal, as compared with electrode metal
armor plates. Although, as previously indicated,
to plate metal ratios of 1 to 1.2 and 1 to 1.94 in
5 the invention is not limited to this preferred form,
Tests 2 and 1, respectively.
‘9 for simplicity of presentation that form is select
Fig. 4 is a scale drawing of the deposits made
ed as an example for detailed description herein.
in'Test 1 (42) and Test 3 (4|) on the steel work
'
The welding current, either alternating or
piece 40, showing the considerable decrease in
direct, is transmitted from a conventional source
penetration of the workpiece brought about by
to the electrode ID by conventional means, for
instance a collet l4, and ?ows to the workpiece 30 the application of preheat to the electrode.
The dilution of electrode metal by metal of the
plates to which the return lead of the current
workpiece may be reduced materially and by a
source is attached. As illustrated in Fig. 1, a
supplementary heating electric current either al
ternating or_direct, is passed through a portion
of the electrode I0 between the collet I4 and a
second collet [5. The magnitude of the sup
; plementary heating current may be controlled by
controlled extent by varying the temperature to
which the electrode is ‘preheated. In general,
the higher the temperature of theelectrode the
lower the penetration of the workpiece and the
lower the percentage dilution of deposited elec
trode metal, all other factors such as amperage
a variable resistance I6 or other appropriate
of the welding current and size and rate of travel
means, and the welding current may be con
trolled in customary manner or by a variable re 40 of the electrode being constant.
sistor l1.
Alternatively, as shown in Fig. 2, the electrode
I claim:
-
1. In the art of electrically melting and de
positing metal from an electrode onto a-metal
may be heated inductively by a suitable coil 20
workpiece and simultaneously melting metal-of
carrying high frequency alternating electric cur
rents. A second alternative, illustrated in Fig. 45 the workpiece and coalescing such melted metal
with the deposited metal by passing an electric
‘"23, is the use of one or, preferably, several ?ames
melting current through said electrode to said
"directed upon the electrode. These ?ames may
workpiece and maintaining a gap between the
comprise any combustible gas or vapor with any
electrode and workpiece, the improvement which
appropriate oxygen-bearing gas, but are prefer
consists in the step of applying only to said elec
ably oxy-acetylene ?ames.
50
trode heat, in addition to the heat derived from
Typical results of the use of this invention,
the electric melting current, in an amount su?l
in comparison with results obtainable by pre
cient to increase the ratio of_melted electrode
viously known procedures, are illustrated by the
metal to melted workpiece metal.
following series of tests. In these tests, the weld
2. The improvement claimed in claim 1, fur
ing method described in Patent 2,043,960 was fol 55
ther characterized in that said additional heat is
lowed, using steel electrodes one-quarter inch in
diameter advanced along the surface of a steel
applied by high frequency alternating electric
. plate at a speed of sixteen inches per minute
I and at a welding current indicated in the ac
' current induced only in said electrode adjacent
the melting end thereof.
a
_
.
companying table. Upon completion of the 60 3. The improvement claimed in claim 1, fur
ther characterized in that said additional heat
welds, the plates and welds were cut transversely
to the lines of the welds, the cut ends were etched
to reveal the metallographic macrostructure of
the deposit and surrounding plate areas, and
I
is applied by high temperature ?ames.
~ EGON B. 'SCHERL.
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