This document is developed in accordance with the rules given in GB/T 1.1-2020 Directives for standardization - Part 1: Rules for the structure and drafting of standardizing documents.
This document replaces GB/T 24179-2009 Metallic materials - Residual stress determination - The indentation strain-gage method. In addition to structural adjustment and editorial changes, the following main technical changes have been made compared with GB/T 24179-2009:
a) The term "coefficients of calibration" has been changed to "strain calculation function" (see Clause 3 herein; Clause 3 of Edition 2009);
b) Some symbols and explanations have been changed (see Clause 4 hereof; Clause 4 of Edition 2009);
c) The principle description has been changed (see Clause 5 hereof; Clause 5 of Edition 2009);
d) The description of the piecewise linear relationship Equation (2) has been deleted and Equation (3) has been deleted (see Clause 5 of Edition 2009);
e) The 60 Ω strain rosette resistance value has been deleted (see 6.2.1 of Edition 2009);
f) The requirement for film base thickness has been changed (see 6.2.1 hereof; 6.2.1 of Edition 2009);
g) The upper limit of the pressure head diameter has been changed (see 6.2.3 hereof; 6.4.1 of Edition 2009);
h) The normative reference to GB/T 230.2 has been deleted (see 6.4.1 of Edition 2009);
i) The specific regulations for the heat treatment stress relief process of calibration test plates have been added (see 8.2.1 hereof);
j) Clarify the use of at least 7-8 stress levels for calibration to obtain more accurate strain functions, and increase the requirement that the maximum applied stress during calibration shall be less than the material's elastic limit rather than the yield limit (see 8.3.3 hereof; 8.2.3 of Edition 2009);
k) The calibration steps for non-principal stress directions have been changed (see 8.5 hereof, 8.4 of Edition 2009);
l) The test report has added "Model of strain ometer, strain gauges, and indentation generation equipment used" (see Clause 9; Clause 9 of Edition 2009).
Attention is drawn to the possibility that some of the parts of this document may be the subject of patent rights. The issuing body of this document shall not be held responsible for identifying any or all such patent rights.
This document was proposed by China Iron and Steel Industry Association.
This document is under the jurisdiction of National Technical Committee on Iron and Steel of Standardization Administration of China (SAC/TC 183).
This document was firstly issued in 2009; and this edition is the first revision.
Metallic materials - Residual stress determination - Indentation strain-gage method
1 Scope
This document specifies the basic principle, measuring equipment and materials, measuring procedures, determination of stress calculation function and test report for measuring residual stress on the surface of metal materials by indentation strain-gage method.
This document is applicable to the determination of residual stress on the surface of various metal materials with hardness not greater than 50 HRC.
2 Normative references
The following documents contain requirements which, through reference in this text, constitute provisions of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB/T 231.2 Metallic materials - Brinell hardness test - Part 2: Verification and calibration of testing machines
JJG 623 Resistance strain gauge indicators
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
strain increment
Δε
amount of strain change (output) produced by the superposition of the strain changes induced by the residual stress field and the spherical indentation after the indentation is produced on the material surface
3.2
strain calculation function
relationship function between strain increment and elastic strain
Note: It is related to the material to be measured, the shape of strain rosette and the size of spherical indentation. It can generally be obtained by calibration test and used for stress calculation, which can also be referred to as stress calculation function for short.
Foreword i
1 Scope
2 Normative references
3 Terms and definitions
4 Symbols and definitions
5 Principles
6 Measuring equipment and materials
7 Measuring procedures
8 Determination of stress calculation function
9 Test report
Annex A (Normative) Stress calculation methods under different measurement conditions
Annex B (Informative) Calculation method for weld stress (mismatch with base metal strength)
Annex C (Informative) Numerical calibration method of strain function
Bibliography
