Addition of oxyanions to liquid solvents in excess of the number of chloride, bromide, or iodide ions present prevents cracking of titanium-aluminum alloys under exposure to aqueous and other solvent environments. The molar concentration of oxyanion is set from 10 to 100 times higher than concentration of halide ions

Beck, T. R.

English

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September 1970	 Brief 70-10129 
NASA TECH BRIEF 
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 Clearinghouse for Federal Scientific and Technical 
Information, Springfield, Virginia 22151. Requests for individual copies or questions relating to the Tech Brief program may 
be directed to the Technology Utilization Division, NASA, Code UT, Washington, D.C. 20546. 
Stress Corrosion Crack Inhibiting Method for Titanium 
A method is proposed for the prevention of stress 
corrosion cracking of high strength titanium alloys 
under exposure to aqueous and other solvent environ-
ments. It has special pertinence to alloys that contain 
a high weight percent of aluminum. 
The method requires adding a quantity of oxyanions 
to the liquid in excess of the number of chloride, 
bromide or iodide ions present. The oxyanions are 
generally phosphates, chromates, sulfates, nitrates, 
or carbonates. Since the cation does not affect the 
• results, the salts of potassium, sodium, lithium, or 
others may be used. Additionally, organic compounds 
that contain oxyanion -groups, such as nitromethane, 
may be used in organic solvents. 
The amount of additive required is determined by 
the quantity of residual chloride, bromide or iodide 
ions present in the fluid. A significant excess of oxy-
anions should be present relative to the estimated 
amount' of chloride or other harmful ions present. 
Generally, the molar concentration 'of oxyanion is 
set from 10 to 100 times higher than the concentration 
of the halide ions. 
The proposed method is particularly concerned 
with the problem of residual chloride, bromide, or 
iodide ions in titanium metal alloys that are exposed
to inert solvents bearing traces of the same halides. 
Where high concentrations of halide ions (on the order 
of one molar) are present in the solvents, stress cor-
rosion cracking is difficult to prevent. 
Applications may include fuel and storage tanks 
where oxyanions could be added to the contents of 
titanium alloy containers. 
Note: 
Requests for further information may be directed 
to:
Technology Utilization Officer 
NASA Pasadena Office 
4800 Oak Grove Drive 
Pasadena, California 91103 
Reference: TSP70-10129 
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: T. R. Beck of
The Boeing Company
under contract to
NASA Pasadena Office
(NPO- 1027 1) 
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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Stress corrosion crack inhibiting method for titanium

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