ASTM E915-96

Standard Test Method for Verifying the Alignment of X-Ray Diffraction Instrumentation for Residual Stress Measurement

SCOPE
1.1 This test method covers the preparation and use of a flat stress-free test specimen for the purpose of checking the systematic error caused by instrument misalignment or sample positioning in X-ray diffraction residual stress measurement, or both.  
1.2 This test method is applicable to apparatus intended for X-ray diffraction macroscopic residual stress measurement in polycrystalline samples employing measurement of a diffraction peak position in the high-back reflection region, and in which the [theta], 2[theta], and [psi] rotation axes can be made to coincide (see Fig. 1).  
1.3 This test method describes the use of iron powder which has been investigated in round-robin studies for the purpose of verifying the alignment of instrumentation intended for stress measurement in ferritic or martensitic steels. To verify instrument alignment prior to stress measurement in other alloys, base metal powder having the same crystal structure as the alloy should be prepared in similar fashion and used to check instrument alignment at the appropriate diffraction angle.  
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

General Information

• Status: Historical
• Publication Date: 31-Dec-1995
• Technical Committee: E28 - Mechanical Testing
• Drafting Committee: E28.13 - Residual Stress Measurement

Relations

• Replaced By: ASTM E915-96(2002) - Standard Test Method for Verifying the Alignment of X-Ray Diffraction Instrumentation for Residual Stress Measurement
• Effective Date: 10-Apr-1996

Standards Content (Sample)

Designation: E 915 – 96 An American National Standard
AMERICAN SOCIETY FOR TESTING AND MATERIALS
100 Barr Harbor Dr., West Conshohocken, PA 19428
Reprinted from the Annual Book of ASTM Standards. Copyright ASTM
Standard Test Method for
Verifying the Alignment of X-Ray Diffraction Instrumentation
1
for Residual Stress Measurement
This standard is issued under the fixed designation E 915; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
3, 4
1. Scope the diverging or parallel beam types.
3.2 Application of this test method requires the use of a flat
1.1 This test method covers the preparation and use of a flat
specimen of stress-free material that produces diffraction in the
stress-free test specimen for the purpose of checking the
angular region of the diffraction peak to be used for stress
systematic error caused by instrument misalignment or sample
measurement. The specimen must be sufficiently fine-grained
positioning in X-ray diffraction residual stress measurement, or
so that large numbers of individual crystals contribute to the
both.
diffraction peak produced. The crystals must provide intense
1.2 This test method is applicable to apparatus intended for
diffraction at all angles of tilt, c, which will be employed (see
X-ray diffraction macroscopic residual stress measurement in
Note 1).
polycrystalline samples employing measurement of a diffrac-
tion peak position in the high-back reflection region, and in
NOTE 1—Complete freedom from preferred orientation in the stressfree
which the u,2u, and c rotation axes can be made to coincide specimen is, however, not critical in the application of the technique.
(see Fig. 1).
4. Procedure
1.3 This test method describes the use of iron powder which
has been investigated in round-robin studies for the purpose of 4.1 Instrument Alignment:
4.1.1 Align the X-ray diffraction instrumentation to be used
verifying the alignment of instrumentation intended for stress
measurement in ferritic or martensitic steels. To verify instru- for residual stress measurement in accordance with the instruc-
tions supplied by the manufacturer. In general, this alignment
ment alignment prior to stress measurement in other alloys,
base metal powder having the same crystal structure as the must achieve the following, whether the u,2u, and c axes are
variable or fixed (see Fig. 1):
alloy should be prepared in similar fashion and used to check
instrument alignment at the appropriate diffraction angle. 4.1.1.1 The u,2u, and c axes shall coincide.
4.1.1.2 The incident X-ray beam shall be centered on the c
1.4 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the and 2u axes, within a focusing range, which will conform to the
desired error and precision tolerances (see sections 5 and 6).
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica- 4.1.1.3 The X-ray tube focal spot, the c and 2u axes, and the
receiving slit positioned at 2u equals zero degrees shall be on
bility of regulatory limitations prior to use.
a line in the plane of diffraction. Alternatively, for instrumen-
2. Referenced Documents
tation limited to the back reflection region, the diffraction angle
2.1 ASTM Standards: 2u shall be calibrated.
E 11 Specification for Wire-Cloth Sieves for Testing Pur- 4.1.1.4 The proper sample position shall be established,
2
poses using whatever means are provided with the instrument, such
that the surface of the sample is positioned at the u and c axes
3. Significance and Use
, within the focal distance range which will conform to the
3.1 This test method provides a means of verifying instru-
desired error and precision tolerances (see sections 5 and 6).
ment alignment in order to quantify and minimize systematic 4.1.1.5 The angle c must be determined accurately.
experimental error in X-ray diffraction residual stress measure-
4.2 X-Ray Optics:
ment. This method is suitable for application to conventional 4.2.1 When the Ka characteristic radiation doublet is used
diffractometers or to X-ray diffraction instrumentation of either
for stress measurement, it is desirable to select incident and
receiving X-ray beam optics that will produce maximum
1
This test method is under the jurisdiction of ASTM Committee E-28 on
3
Mechanical Testing and is the direct responsibility of Subcommittee E28.13 on Hilley, M. E., Larson, J. A., Jatczak, C. F., and Ricklefs, R. E., eds., Residual
Residual Stress Measurement. Stress Measurement by X-ray Diffraction, SAE J784a, Society of Automotive
Current edition approved Apr. 10, 1996. Published June 1996. Originally Engrs., Inc., Warrendale, PA (1971).
4
published as E 915 – 83. Last previous edit
...