Boron-deoxidized high-conductivity copper is used for fabrication of heat transfer components that are brazed in a hydrogen atmosphere. This copper has high strength and ductility at elevated temperatures and does not exhibit massive intergranular failure

Schmidt, E. H.

English

NASA Technical Reports Server

July 1966
	 Brief 66-10273 
S
NASA TECH BRIEF 
NASA Tech Briefs are issued to summarize specific innovations derived from the U. S. space 
program and to encourage their commercial application. Copies are available to the public from 
the Clearinghouse for Federal Scientific and Technical Information, Springfield, Virginia 22151. 
Boron—Deoxidized Copper Withstands Brazing Temperatures 
The problem: 
OFHC (Oxygen Free High Conductivity) plate 
copper used for fabrication of components that are 
brazed in a hydrogen atmosphere to heat transfer 
equipment is subject to extensive grain growth and 
a loss of strength at the high brazing temperatures 
(15500 F for an average exposure of 5 to 6 hours). 
• The copper components installed in the heat transfer 
equipment are also required to withstand operating 
temperatures ranging from 500° to 1220° F without 
degradation of their mechanical properties. 
The solution: 
Use a commercially available boron-deoxidized, 
high-conductivity copper (0.005 to 0.015% boron) 
for fabricating the heat transfer components. The re-
sults of comparative tests show that the boron-
deoxidized copper has higher strength and ductility 
than OFHC copper at elevated temperatures and does 
not exhibit massive intergranular failure. 
How it's done: 
OFHC copper and boron-deoxidized copper in the 
form of 5/8-inch-thick plate were used for machining 
of round tensile test specimens, which were then 
annealed at 925 ± 20° F for 5 to 10 minutes in an 
argon atmosphere. One-half of each group of speci-
mens were grain coarsened during a production braze 
cycle at 1910° F. 
Tensile tests were run at room temperature and 
at 200° F, 300° F, 4000 F, 500° F, and 900° F. The 
specimens were heated in air and held at tempera-
ture for 15 minutes prior to tensile testing at a 
cross-head speed of 0.005 inch/inch/minute. Grain-
size and hardness measurements were made for both
copper materials in the fine grained and coarse grained 
conditions. Representative tensile specimens were 
cross-sectioned for metallurgical investigation. The 
following is a summary of the results of the tests on 
the two groups of specimens: 
1. OFHC copper, coarsened on exposure to the 
1910° F braze cycle, exhibited tensile strengths of 
approximately 10,000 psi at 900° F. The yield 
strength remained low (5,000 psi) at all tempera-
tures between room temperature and 900° F. The 
boron—deoxidized copper, exposed to the same 
braze cycle, exhibited slightly higher strength and 
ductility values than OFHC copper. 
2. The braze cycle produced greater grain growth 
in the OFHC copper than in the boron—deoxidized 
copper. 
3. Coarse grained OFHC copper failed intergranu-
larly at temperatures of 400° F and higher. The 
coarse grained boron—deoxidized copper did not 
exhibit massive intergranular failure at any test 
temperature. 
4. There was no significant difference in hardness 
between either copper material when tested in the 
annealed or brazed condition. 
Note: 
Inquiries concerning this innovation may be di-
rected to:
Technology Utilization Officer 
Marshall Space Flight Center 
Huntsville, Alabama 35812 
Reference: B66-10273
(continued overleaf) 
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 owned rights.
https://ntrs.nasa.gov/search.jsp?R=19660000272 2020-03-11T17:38:31+00:00Z
Patent status: 
Inquiries about obtaining rights for the commercial 
use of this invention may be made to NASA, Code 
GP, Washington, D.C., 20546, 
Source: Erwin H. Schmidt 
of North American Aviation, Inc.
under contract to
Marshall Space Flight Center
(M-FS-762)
Category 03 
Brief 66-10273


Boron-deoxidized copper withstands brazing temperatures

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