This file is based on GB/T1.1-2020 "Standardization work Guidelines Part 1: Standardization document structure and drafting rules" draft provisions。

This document replaces GB/T 28896-2012 "Test method for the determination of quasi-static fracture toughness of welded joints of metal materials", compared with GB/ T28896-2012, in addition to structural adjustment and editorial changes, the main technical changes are as follows:

- Added the formula for estimating tensile strength at low temperatures based on tensile strength at room temperature (see 12.1);

- Added a series of formulas for calculating the crack tip opening displacement δ for deep notches (see 12.2);

- Changed the calculation formula of output estimate V of the double-extender for shallow notch three-point bending specimen, the calculation formula of single-point J integral, the calculation formula of single-point crack tip opening displacement eigenvalue (δ) and the calculation formula of single-point crack tip opening displacement eigenvalue (δ) (see Appendix E),Appendix E of the 2012 edition)。

This document is modified to adopt ISO 15653:2018 "Test method for the Determination of quasi-static fracture toughness of welded joints of Metal materials".。

The technical differences between this document and ISO 15653:2018 and their reasons are as follows:

ISO 12135 has been replaced with normative reference document GB/T21143 to meet our technical requirements (see Chapters 3, 4, 5, 6).2、8.1、8.4、9.1、9.2、第10章、12.2.1、12.2.2、12.3.1、12.3.2、12.3.3、12.3.4, Chapter 13, D.1、D.2、D.5、E.2、E.3)。

-- Changed for deep notch (0.45

In order to be consistent with the standard technical content, the information Appendix E is changed to the normative appendix。

The following editorial changes have been made to this document:

-- Corrected the errors noted in Figure 9;

-- The numbering of formula (11) ~ (15) was changed from formula (11) ~ (15) to formula (12) ~ (16);

-- Changes the formula in Appendix E (E.3) The symbol, will be symbol A。Change to Ap;

An example of "The sum of the cumulative lengths of specific microstructure regions within 75% thickness through the thickness notched sample center" has been added to the information Appendix B;

-- Added references [3]。

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