Welding technique uses very small quantities of explosive ribbon to accomplish small-scale lap-welding of aluminum plates. Technique can perform small controlled welding with no length limitations and requires minimal protective shielding

Bement, L. J.

English

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W e I d I n g
	 S e $ U p Ex p1 Os iv e 
Metal To Be We Bose Plate 
•'	 -r 
Pull Tests
Pull Tests 
1972
	 B72-10002 
NASA TECH BRIEF 
Langley Research Center 
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 National Technical Information 
Service, Springfield, Virginia 22151. Requests for individual copies or questions relating to the Tech Brief program may 
be directed to the Technology Utilization Office, NASA, Code KT, Washington, D.C. 20546. 
Small-Scale Explosive Welding of Aluminum 
I	 I 
:	 :	
Area Welded 
Weld 
A new welding technique is being developed which 
uses very small quantities of a new explosive ribbon to 
accomplish small-scale lap-welding of aluminum plates. 
This simple technique can perform small controlled 
welding with no length limitations and requires minimal 
protective shielding. 
The explosive, lead-sheathed RDX ribbon, has been 
specially designed to NASA specifications. The highest 
ribbon rating used in the present investigation is 5.32 
g/m (25 grains/ft) which is 0.89-mm (0.035-in) thick. 
Sheet stocks of 2024-T3 AlcIad, 2024-0, 6061-0, 7075-0, 
and 1100 in thicknesses from 0.84 to 3:18 mm (0.033 
to 0.125 in) have been welded to 6.35 mm (0.250 in) 
plates of the same alloy and in other combinations 
thereof. Also, 6061-T6 has been welded to the above 
alloys and to 6061-T6, and 7075-T6 has been welded to 
2024.T3 Alclad and to 6061-T6.
The surfaces to be welded are first prepared by 
chemical cleaning (except for commercially-pure alum-
inum, which is simply wiped with a solvent) and then 
positioned with a separation of 0.25 mm (0.010 in) by 
use of two parallel spacers 2.54 cm (1 in) apart. Welding 
is accomplished by igniting an explosive ribbon lying on 
the metal directly above the 0.25-mm (0.010 in) 
channel. 
The explosion generates a pressure of several billion 
N/rn 2 (several million psi) with which it drives a zone 
of the metal into the plate and forms a molecular bond 
at the interface, as shown in the figure. Welding under 
these conditions is essentially a high-velocity "cold-
working" process which does not affect the temper of 
the metal. 
Shear pull tests have been performed on welds of all 
combinations of the alloys mentioned which used RDX 
(continued overleaf) 
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Aeronautics and Space Administration. Neither the United States 	 information contained in this document, or warrants that such use 
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ribbon ratings of 1.5, 2.1, 3.2, 4.3, and 5.3 gm/rn (7, 
10, 15, 20 and 25 grains/ft). Results show that weld set-
ups (explosive quantity/metal thickness) can be optimized 
to provide weld strength up to 90 percent of the tensile 
strength of the parent metal. This lower weld strength is 
caused by the pressure-induced indentation which de-
creases the cross-sectional area of the metal. 
This technique has a further capability in the welding 
of plates of equal thicknesses. In this case, the plate is 
first separated by as little as 0.25 mm (0.010 in). A 
ribbon explosive is then placed on each side of the 
stacked plate directly opposite each other and the explo-
sion is initiated. The plates are driven together, and, on 
impact, a weld is produced in the same manner described 
earlier. Since the two explosive ribbons are directly 
opposing, no unbalancing forces are created and, conse-
quently, no displacement occurs. 
In addition to explosive welding under normal atmo-
spheric conditions, satisfactory results were also obtained 
under a vacuum of 2 x 10 Torr.
Note: 
Requests for further information may be directed to 
Technology Utilization Officer 
Langley Research Center 
Langley Station Mail Stop 139A 
Hampton, Virginia 23365 
Reference: TSP72-10002 
Patent status: 
Inquiries about obtaining rights for the commercial 
use of this invention may be made to Patent Counsel, 
NASA Langley Research Center, Hampton, Virginia 
23365.
Source: L. J. Bement
Langley Research Center 
(LAR-10941) 
B72.10002	 Category 04


Small-scale explosive welding of aluminum

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