Appropriate brazing metals and temperatures facilitate the welding or brazing of base metals with tungsten inert gas equipment. The highest quality bond is obtained when TIG welding is performed in an inert atmosphere

Wisner, J. P.

English

NASA Technical Reports Server

October 1965
	 Brief 65-10319 
NASA TECH 
NASA Tech Briefs are issued by the Technology Utilization Division to summarize specific 
technical innovations derived from the space program. Copies are available to the public from 
the Clearinghouse for Federal Scientific and Technical Information, Springfield, Virginia, 22151. 
Refractory Metals Welded or Brazed With Tungsten Inert Gas Equipment 
The problem: To weld or braze certain metals, in-
cluding refractory metals, which are difficult or im-
possible to join by conventional welding or brazing 
methods. In order to obtain satisfactory bonds be-
tween such metals, using tungsten inert gas JIG) 
welding equipment, the welding or brazing (with ap-
propriate brazing or filler metals) must be performed 
at prescribed temperatures and under protective at-
mospheres for some metal combinations. 
The solution: Appropriate brazing metals, brazing 
temperatures, and welding temperatures are pre-
scribed for a number of base metals that cannot be 
satisfactorily bonded by conventional methods. When 
the prescribed temperatures and specific brazing 
metals are used, the base metals can be firmly welded 
or brazed with TIG equipment. Inert atmosphere 
chambers must be used for certain metal combina-
tions. 
How it's done: When a brazing metal is used, the 
operation is performed at a temperature above the 
melting point of the brazing metal but below the melt-
ing points of the base metals to be joined. At this tem-
perature, the molten brazing metal flows into the base-
metal seam and forms a tight metal-to-metal bond on 
cooling. Brazing metals consisting of columbium-l% 
zirconium at approximately 4,400 1 F or titanium at 
approximately 3,300° F have been used to join tan-
talum to tungsten, tungsten to molybdenum, and 
molybdenum to tantalum. Molybdenum has been 
joined to stainless steel using the following brazing 
metals at the indicated approximate temperatures: 304 
stainless steel at 2500°F; silver solder at 1200° to 
1900°F; Inconel at 2500°F; gold-silver solder at 
1900 0 17; and oxygen-free, high-conductivity copper at 
1980° F.
The following metals have been brazed using spe-
cific silver solder formulations at 1200° to 1900°F: 
beryllium copper to beryllium copper; stainless steel to 
stainless steel; brass to stainless steel; copper to stain-
less steel; and aluminum to stainless steel. 
To join two base metals by welding (without the use 
of a brazing metal or a flux) the welding temperature 
is kept for a short time at or above the melting point of 
the lower melting metal, but below the melting point 
of the other metal. The molten surface layers of the 
lower melting metal wet the second metal and form a 
metal-to-metal bond on cooling. This welding opera-
tion is preferably carried out in an inert-gas medium 
to protect the weld puddle from the atmosphere. The 
following pairs of base metals have been welded by 
this method. (The approximate temperature at which 
the second metal in each pair wets the first metal is 
given in parentheses.): Tungsten to columbium 
(4500, F); molybdenum to stainless steel (2700,F); 
stainless steel to copper (2000 0 F); molybdenum to 
cpper (2000°F); and tantalum to copper (2000°F). 
Notes: 
1. The highest quality bond is obtained when TIG 
welding is performed in an inert-gas welding cham-
ber or under an inert-gas blanket. 
2. Metal plating on small parts or on localized areas 
of large parts can be performed using TIG equip-
ment as prescribed above. 
3. Inquiries concerning this innovation may be di-
rected to: 
Technology Utilization Officer 
Lewis Research Center 
21000 Brookpark Road 
Cleveland, Ohio, 44135 
Reference: B65-10319
(continued overleaf) 
This document was prepared under the sponsorship of the National 
Aeronautics and Space Administration. Neither the United States 
Government nor any person acting on behalf of the United States
Government assumes any liability resulting from the use of the 
information contained in this document, or warrants that such use 
will be free from privately owned rights.
https://ntrs.nasa.gov/search.jsp?R=19650000317 2020-03-11T17:21:23+00:00Z
Patent status: NASA encourages commercial use 
of this innovation No patent action is contemplated 
by NASA.
Source: John P. Wisner 
(Lewis-219) 
Brief 65-10319	 Category 05


Refractory metals welded or brazed with tungsten inert gas equipment

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