Modified testing system determines tensile properties of irradiated brittle-type metals at cryogenic temperatures. The system includes a lightweight cryostat, split-screw grips, a universal joint, and a special temperature control system

Levine, P. J.

Skalka, R. J.

Vandergrift, E. F.

English

NASA Technical Reports Server

Tensile 
Specimen 
Acrylite 
Window Tensile Testing	 Thermocouple	 Recorder- 
\	 Mechanism [Wires	 /Controller 
Lightweight 
Polystyrene 
Cryostat 
Perforated Gas 
Feeding Coil 
Split-Screw 
Assemblies 
^"_T 
Bottom 
Pull Rod-.. 
Split-Screw 
SPLIT-SCREW GRIPS
New I 
Joint 
Heatin 
Coil 
Helium—
Tank 
Q 
NEW UNIVERSAL JOINT
'J	 II ___ 1 
Tensile	 LfIIl	 I 
Specimen1l	 I 
LN2 Dewar	 Ei 
i	
lI
000 I 
December 1967
	
Brief 67-10617 
toy e
AEC-NASA TECH BRIEF 
TES
AEC-NASA Tech Briefs describe innovations resulting from the research and development program 
of the U.S. AEC or from AEC-NASA interagency efforts. They are issued to encourage commercial 
application. Tech Briefs are published by NASA and may be purchased, at 15 cents each, from 
the Clearinghouse for Federal Scientific and Technical Information, Springfield, Virginia 22151. 
Test System Accurately Determines Tensile Properties

of Irradiated Metals at Cryogenic Temperatures 
The problem: 
Previous radiation-effects tensile testing of brittle-
type metals indicated losses in strength and ductility 
after irradiation at 140°R in liquid nitrogen (LN2). 
The measured properties appeared to be affected by 
premature failure caused by eccentricity of the loading 
system of the tensile testing equipment. A need was 
also apparent for fast, accurate control of specimen 
temperature during testin g at intermediate tempera-
tures (from 190 0 R, up) to determine annealing effects. 
The solution: 
A standard tensile testing system modified by the 
incorporation of (I) a lightweight cryostat, (2) split-
screw grips, (3) a universal joint, and (4) a special 
temperature control system. 
This document was prepared under the sponsorship of the Atomic 
Energy Commission and/or the National Aeronautics and Space 
Administration. Neither the United States Government nor any per-
son acting on behalf of the United States Government assumes any
How it's done: 
The cryostat is made of a lightweight material (ex-
panded polystyrene with a density of I lb/ft 3), which 
reduces misalignment effects formerly caused by the 
greater weight of conventional metal cryostats. It 
contains two acrylite windows, which facilitate view-
ing the split-screw grips and loading the specimen 
under LN2. This system was developed for testing 
metal specimens irradiated at 140 0 R. The specimen 
must be kept under LN2 during irradiation and there-
after until the LN2 is drained from the cryostat at 
the appropriate stage in the test procedure. The cryo-
stat is attached directly to the bottom pull rod by a 
special seal, eliminating the need for complicated 
dynamic seals.
(continued overleal) 
liability resulting from the use of the information contained in this 
document, or warrants that the use of any information, apparatus, 
method, or process disclosed in this document may not infringe pri-
vately owned rights.
https://ntrs.nasa.gov/search.jsp?R=19670000616 2020-03-11T21:26:52+00:00Z
The split-screw grips are precision machined to the 
contour of the test specimen shoulders to reduce mis-
alignment effects due to uneven loading. Unlike con-
ventional split-screw grips, which are threaded to the 
end of the unit, the new grips are made with a guide 
and beveled edge to facilitate rapid and accurate 
seating under LN2. Also, the heads contain precision-
located holes that match precision-located pins in a 
specially designed wrench; this permits rapid assembly 
of the split-screw grips around the specimen and as-
sembly into the main grip body under LN2 without 
jamming. 
To further reduce misalignment effects, a universal 
joint with limited side travel is inserted in the socket 
located on the movable crosshead and is connected 
with the bottom pull rod. Semielliptical design of 
the universal-joint head and the socket seal limits side 
travel to minimize any random stresses or spillage of 
LN2 that might be caused by "flopping" of the uni-
versal joint before slack in the system is taken up. 
In the temperature control system, the specimen is 
surrounded by a coil containing specially sized and 
specially located holes through which either cold gas-
eous nitrogen or preheated gaseous helium may be 
injected through lines leading into the coil from an 
LN2 dewar or a helium tank. Temperature is deter-
mined from a calibrated thermocouple at a control 
point near the specimen and is maintained at the 
desired set point (after the LN2 has been drained 
from the cryostat) by a controller which actuates 
solenoid valves as required.
Notes:	 - 
1. By using this improved test system, misalignments 
may be reduced to less than 5°,, and specimen 
temperature can be controlled within ±2° R at tem-
peratures as low as 1900R. 
2. The system was developed for use in determining 
the radiation effects on cryogenic tensile proper-
ties of beryllium. It should be easily applicable to 
the determination of tensile properties of other 
materials at cryogenic temperatures where mis-
alignment of the testing system is a factor and 
close temperature control is desirable. 
I. Inquiries concerning this innovation may be di-
rected to:
Technology Utilization Officer 
AEC—NASA Space Nuclear Propulsion 
Office 
U.S. Atomic Energy Commission 
Washington, D.C. 20545 
Reference: B67-10617 
Patent status: 
No patent action is contemplated by AEC or 
NASA.
Source: P. J. Levine, R. J. Skalka,

And E. F. Vandergrift 
of Westinghouse Astronuclear Laboratory

under contract to

AEC—NASA Space Nuclear Propulsion Office 
(N UC- 10521) 
Brief 67-10617	 Category 02


Test system accurately determines tensile properties of irradiated metals at cryogenic temperatures

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