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GB/T 40307-2021 (GB/T40307-2021, GBT 40307-2021, GBT40307-2021)
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GB/T 40307-2021: PDF in English (GBT 40307-2021)

GB/T 40307-2021
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 19.100
CCS J 04
Non-Destructive Testing - Test Method for Texture by
Neutron Diffraction
ISSUED ON: MAY 21, 2021
IMPLEMENTED ON: DECEMBER 01, 2021
Issued by: State Administration for Market Regulation;
Standardization Administration of PRC.
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Normative References ... 4
3 Terms and Definitions ... 4
4 Principle ... 5
5 Apparatus ... 6
6 Preparation for Measurement ... 8
7 Measurement ... 13
8 Data Processing and Analysis ... 14
9 Test Report ... 16
Bibliography ... 18
Non-Destructive Testing - Test Method for Texture by
Neutron Diffraction
1 Scope
This Document specifies the method for detecting the texture of materials on the
reactor by neutron diffraction technology.
This Document is applicable to the detection of texture of polycrystalline materials.
2 Normative References
The following documents are essential to the application of this Document. For the
dated documents, only the versions with the dates indicated are applicable to this
Document; for the undated documents, only the latest version (including all the
amendments) is applicable to this Document.
GB/T 12604.8 Terminology for Non-Destructive Testing - Neutron Testing
GB/T 26140 Non-Destructive Testing - Standards Test Method for Determining
Residual Stresses by Neutron Diffraction
3 Terms and Definitions
For the purposes of this Document, the terms and definitions given in GB/T 12604.8
and GB/T 26140 and the following apply.
3.1 Texture
The crystal grains in the polycrystalline sample are arranged in different directions with
different orientation characteristics, which is manifested as the preferred orientation
structure of the sample.
NOTE: The neutron detection method can obtain pole figures of multiple crystal planes, obtain
accurate orientation directions, and obtain quantitative data of texture intensity.
3.2 Neutron diffractometer for texture measurement
Neutron radiation detection device for measuring texture of materials.
3.3 Pole figure
The projection map of the orientation distribution of the selected crystal plane of each
crystal grain in the material in the sample coordinate system.
NOTE: The sample coordinate system refers to the rectangular orthogonal coordinate system
established according to the sample shape, which is the basic expression form of texture
intensity.
3.4 Inverse pole figure
The projection map of the orientation distribution of the selected crystal plane of each
crystal grain in the material in the crystal coordinate system.
NOTE: The crystal coordinate system refers to the rectangular coordinate system established
in accordance with the crystal orientation, which is the basic expression form of texture intensity.
3.5 Pole density
Polycrystalline materials are projected to the polar equator, and the weighted density
distribution of the crystal grain volume represented by each point on the sphere.
3.6 Orientation distribution function
An optimized azimuth expression form of the three-dimensional spatial distribution of
crystal elements.
4 Principle
After being irradiated by neutron rays, a polycrystalline sample with regularly arranged
atoms shall produce coherent scattering at a specific angle. This process is called
Bragg diffraction, and the process is given by Formula (1):
Where:
d – interplanar spacing, in nm;
θ – 1/2 diffraction angle, in °;
λ – neutron wavelength, in nm.
The texture shall cause the Bragg diffraction peaks of the sample in the three-
dimensional space and cause the changes in intensity. The texture intensity of the
material is obtained by collecting the diffraction peaks of different spatial angles in the
three-dimensional space and analysing the diffraction peaks.
The monochromator is a device that uses crystals to select and reflect rays. The
monochromator is mainly composed of single crystal, focusing device, adjustment
table and other components. The energy range of the neutron beam selected by the
monochromator should be 5meV~25meV; and the corresponding neutron wavelength
range is 0.1nm~0.3nm. The monochromator should have vertical focusing or horizontal
and vertical double focusing capabilities to increase the neutron fluence rate at the
sample. The monochromators commonly used in neutron diffractometer for texture
measurement include: silicon monocrystalline monochromator, pyrolytic graphite
monocrystalline monochromator, monocrystalline germanium monochromator, and so
on.
5.2.3 Euler ring
The Euler ring is used to realize the assembly and positioning of the sample, and to
provide the rotation of the sample in the three-dimensional space coordinate. The Euler
ring shall realize the sample rotation azimuth φ and the Euler ring rotation azimuth χ
according to the set pace and ensure the angular accuracy. Among them, the φ angle
should be in the range of 0°~360°, the χangle should be in the range of 0°~360°, and
the angular accuracy should be better than 0.1°.
5.2.4 Detector
The detector is a device for capturing and recording neutron signals. The detector can
detect neutron energy in the range of 5meV~25meV. Commonly used detectors on
neutron diffractometer for texture measurement include 3He counter tube detectors,
3He gas multifilament position sensitive detectors, and so on.
6 Preparation for Measurement
6.1 Neutron wavelength selection and calibration
6.1.1 Confirm the crystal structure information of the sample.
6.1.2 Select the crystal plane to be tested and neutron wavelength of the sample.
6.1.3 According to the selected neutron wavelength, set the monochromator take-off
angle and focus parameters to a neutron beam obtained at that wavelength of the
sample.
6.1.4 After the neutron wavelength is set, the standard calibration sample is used to
measure the diffraction spectrum of multiple crystal planes of the sample; and the
actual neutron wavelength is obtained through the peak position fitting analysis and
calculation of the diffraction spectrum. The calibration of the neutron wavelength and
the error value is given by Formula (2). According to the recommendation of the
International Neutron Scattering Agency, the neutron wavelength resolution Δλ/λtest
should be better than 1×10-2. The commonly used calibration samples include silicon
powder, iron powder, aluminium oxide powder, and so on.
Where:
λ- neutron wavelength, in nm;
λtest – neutron wavelength in test, in nm;
λtheory – neutron wavelength in theory, in nm.
6.2 Calibration of mechanical positioning accuracy
6.2.1 Set the detector rotation angle, Euler ring inclination angle and sample rotation
angle, respectively; and build an angular accuracy detection device at this angular
position.
6.2.2 Drive each rotation angle to control the motor; so that make each rotation angle
that deviates from the set position to the set angle; and the repeatability accuracy is
obtained by measurement.
6.2.3 Arrange the theodolite at the position corresponding to the centre of circle for
each rotation angle; measure the absolute angle value from the beginning of the
rotation angle to the set value; and obtain the absolute accuracy by the measurement.
6.3 Calibration of spectrometer resolution
6.3.1 The resolution of the spectrometer usually refers to the resolution of the
interplanar spacing.
6.3.2 The standard calibration sample is installed in the centre of the sample bench;
and select the measurement crystal plane and its corresponding diffraction angle.
6.3.3 Set the focus parameters and diffraction angle of the monochromator of the
spectrometer; and carry out the collection of the diffraction spectrum of the selected
crystal plane.
6.3.4 Obtain the measured d value of the standard sample according to the diffraction
peak position.
6.3.5 Use the measured interplanar spacing d value and the sample theoretical
interplanar spacing d0 to calculate the spectrometer resolution (Δd/d), which is given
by Formula (3):
2 - regular diffraction peaks on the background;
I --- diffraction peak intensity;
BG - diffraction background, the signal caused by stray neutrons;
2θ - diffraction angle, in °.
Figure 6 -- Background Deduction Method of Diffraction Peaks
8.2 Correction of temperature influence
8.2.1 The experimental temperature change causes the change of the sample lattice
spacing d, which indirectly leads to the change of the diffraction peak intensity.
8.2.2 When the temperature change during the texture detection experiment is within
5°C, the fluctuation of the diffraction peak intensity caused by the temperature change
(uniformly changed to the intensity change) is less than one ten-thousandth, then its
influence is negligible.
8.2.3 When the temperature change during the experiment exceeds 5°C, the change
in interplanar spacing shall be calculated according to the thermal expansion
coefficient of the sample; and the fluctuations of diffraction peak intensity caused by
this change shall be included in the texture intensity error analysis. The temperature
of the sample shall be monitored during measurement.
8.3 Data analysis
8.3.1 Polar density distribution function
The polar density distribution function phkl (χ, φ) is given by Formula (6):
Where:
χ- rotation azimuth of Euler ring, in °;
φ – rotation azimuth of sample, in °;
Ihkl (χ , φ) - integrated intensity of the (hkl) crystal plane diffraction peak of the
specimen in the (χ, φ) direction.
8.3.2 Calculation of orientation distribution function and texture strength
Confirm the orientation direction y of the sample. The orientation direction y of the
sample is related to the Euler angleχ and φ; and their relationship satisfies Formulas
......
 
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.