Stress corrosion of titanium and its alloys at elevated temperatures is minimized by replacing trichloroethylene with methanol or methyl ethyl ketone as a degreasing agent. Wearing cotton gloves reduces stress corrosion from perspiration before the metal components are processed

Carpenter, S. R.

English

NASA Technical Reports Server

Sentember 1967
	 Brief 67-10147 
c4ff 
NASA TECH BRIEF 
NASA Tech Briefs are issued to summarize specific innovations derived from the U.S. space program,. 
to encourage their commercial application. Copies are available to the public at 15 cents each 
from the Clearinghouse for Federal Scientific and Technical Information, Springfield, Virginia 22151. 
Degreasing of Titanium to Minimize Stress Corrosion 
The problem: 
Cleaning agents such as trichioroethylene, metha-
nol, methyl ethyl ketone and acetone have been used 
as degreasing agents in the processing of titanium. 
Use of trichioroethylene and high purity (>98%) 
methanol have been found to cause severe stress corro-
sion on titanium and some of its alloys. Even residual 
traces of trichioroethylene can promote appreciable 
stress corrosion, especially when the metal is subjected 
to high temperatures. Other liquids may potentially 
affect titanium due to reactivity of titanium. Even 
perspiration from the hands deposited on titanium 
also contributes to stress corrosion at higher tempera-
tures. 
The solution: 
Limited experience indicates that stress corrosion in 
titanium is lessened by using methanol diluted with at 
least 2% distilled water as a cleaning agent. This is 
not to imply that problems will not arise from the use 
of these cleaning agents. The mechanism which pro-
duces stress corrosion in titanium from various clean-
ing agents is not thoroughly understood. It is, there-
fore, recommended that the possible degradation of 
titanium and its alloys be investigated prior to selec-
tion of a cleaning agent by performing pre-flawed 
sustained load tensile tests in the cleaning environ-
ment. The specimen containing a crack-like flaw 
should be loaded to the operating stress for the service 
structure at the highest temperature in the service 
environment. Clean cotton gloves should be worn 
when handling the metal and its alloys. 
Notes: 
1. Exposure of titanium and its alloys to fumes of 
trichloroethylene (from nearby degreasing areas) 
should be avoided whenever these metals are to be 
processed.
. It should be noted that the stress corrosion suscep-
tibility of titanium alloy varies considerably from 
alloy to alloy. 
3. Additional information on titanium stress corro-
sion is contained in NASA CR-65586, Investigation 
of the Flaw Growth Characteristics of 6A14V 
Titanium used in Apollo Spacecraft Pressure 
Vessels, March 1967. This report is available from 
the Clearinghouse for Scientific and Technical 
Information, Springfield, Virginia 22151, $3.00 
each; microfiche, $0.65. 
. Inquiries concerning this innovation may be di-
rected to:
Technology Utilization Officer 
Lewis Research Center 
21000 Brookpark Road 
Cleveland, Ohio 44135 
Reference: B67-10147 
or to:
New Technology Representative 
General Dynamics/Convair Division 
Mail Zone 103-19 
5001 Kearny Villa Road 
San Diego, California 92112 
Reference: B67-10147 
Patent status: 
No patent action is contemplated by NASA. 
Source: S. R. Carpenter 
of General Dynamics/Convair Division 
under contract to 
Lewis Research Center 
and Gordon T. Smith and Richard N. Johnson 
of Lewis Research Center 
(Lewis-382) 
Category 03 
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.
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Degreasing of titanium to minimize stress corrosion

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