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This standard is drafted in accordance with the rules given in GB/T 1.1-2009.
This standard is a revision of YB/T 5338-2006 Retained austenite in steel—Quantitative determination—Method of X-ray diffractometer.
The following main technical changes have been made with respect to YB/T 5338-2006:
a) The word “retained” in the standard name is deleted;
b) The application scope of the standard is expanded;
c) The clause “Terms and definitions” is added;
d) The whole powder pattern fitting method is added;
e) The name of the method is added. The method of YB/T 5338-2006 is defined as “five-line six-pair method”, and the added method is defined as “whole powder pattern fitting method”, and the preconditions for the application of various methods are specified;
f) The specific contents of whole powder pattern fitting method are added: principle and calculation equation, test conditions, refinement process and result judgment, etc.;
g) Some of the names and symbols are modified: “martensitic phase” and “austenite phase” are modified to “alpha phase” and “gamma phase”, respectively; the symbols “M” and “A” are modified to “α” and “γ” respectively;
h) The scanning speed of the diffractometer at 2θ angle is modified from “not more than 1 °/min” to “≤ 2 °/min”.
This standard was proposed by China Iron and Steel Industry Association.
This standard is under the jurisdiction of National Technical Committee on Iron and Steel of Standardization Administration of China (SAC/TC 183).
Quantitative determination of austenite in steel—
Method of X-ray diffractometer
1 Scope
This standard is applicable to the determination of the austenitic contents in the quantitative determination, low carbon steel and medium or low carbon low alloy steel by the X-ray diffractometer method. For other steel grades, this standard may be referred to.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated reference, only the edition cited applies. For undated references, the latest edition of the normative document referred to applies.
GB/T 30067 Standard terminology relating to metallography
JY/T 009 General rules for X-ray polycrystalline diffractometry
3 Terms and definitions
For the purposes of this document, the terms and definitions given in GB/T 30067 and the following apply.
3.1
alpha phase
body-centered cubic solid solution of carbon or other elements in α-Fe, including martensite, ferrite, etc.
3.2
gamma phase
face-centered cubic solid solution of carbon or other elements in γ-Fe, that is, austenite
3.3
texture
polycrystalline orientation structure with preferred orientation
Note: Preferred orientation means that many grain orientations are concentrated and distributed near one or some specific positions
3.4
whole powder pattern fitting
method that in the whole diffraction pattern range, on the premise of a crystal structure model, the polycrystalline diffraction pattern is calculated by combining the structural parameters, instrument parameters and peak shape function. By adjusting these structural parameters and peak shape function, the calculated polycrystalline diffraction pattern can be consistent with the actual pattern, so as to obtain the actual structural parameters of the sample
3.5
comprehensive stability of X-ray diffractometer
the measured maximum relative fluctuation of the intensity count value of diffraction ray every 15 min for a continuous day when the sample, diffraction conditions and diffraction ray remain unchanged, after the diffractometer is stable
4 Apparatus and their requirements
The comprehensive stability of X-ray diffractometer shall meet the requirements of Equation (1), and the count per second (CPS) shall not be more than 5 × 103, and the cumulative intensity shall not be less than 1 × 106 each time.
Allowable comprehensive stability=(N_max-N_min)/N ̅ ≤1% (1)
where,
Nmax——the maximum count value;
Nmin——the minimum count value;
¯N——the average count value.
5 Preparation of specimen
5.1 Dimensions of specimen
The specimen shall be flat, and the measuring surface dimension shall be 20 mm × 20 mm or more, which may be appropriately changed according to specific conditions. However, under the corresponding slit system, it shall be ensured that the X-ray irradiation area at the selected diffraction position shall not exceed the measured surface of the specimen.
Foreword i
1 Scope
2 Normative references
3 Terms and definitions
4 Apparatus and their requirements
5 Preparation of specimen
6 Inspection methods
7 Test conditions
8 Result calculation
9 Test report
