GB/T 15970.7-2017Corrosion of metals and alloys -- Stress corrosion testing -- Part 7: Slow strain rate testing (English PDF)

Foreword

GB/T 15970 "Corrosion of metals and alloys - Stress corrosion test" is divided

into the following parts.

- Part 1. General guidance on testing procedures;

- Part 2. Preparation and use of bent-beam specimens;

- Part 3. Preparation and use of U-bend specimens;

- Part 4. Preparation and use of uniaxially loaded tension specimens;

- Part 5. Preparation and use of C-ring specimens;

- Part 6. Preparation and use of pre-fractured specimens;

- Part 7. Slow strain rate testing;

- Part 8. Preparation and use of specimens to evaluate weldments;

- Part 9. Preparation and use of pre-fractured specimens for tests under

rising load or rising displacement.

This part is the part 7 of GB/T 15970.

This part was drafted in accordance with the rules given in GB/T 1.1-2009.

This part replaces GB/T 15970.7-2000 "Corrosion of metals and alloys - Stress

corrosion testing - Part 7. Slow strain rate testing". As compared with GB/T

15970.7-2000, the main technical changes are as follows.

- MODIFY the normative references;

- ADD the definition of plastic strain to failure;

- MODIFY the definition of elongation to fracture, reduction of area, strain

rate;

- ADD the descriptions for the number of specimens in each group;

- ADD the requirements for reagents;

- DELETE the description that "If the total test time of the test at a very slow

strain rate is required, it is needed to preload the specimen";

- ADD the description of important parameters of environmental factors;

- ADD the descriptions for the factors which affect the potential of the metal

electrode;

- ADD the provisions for the auxiliary electrodes that generate external

currents;

- ADD the requirements for the ratio of solution volume to specimen's surface

area;

- ADD the sensibility of the use of plastic strain to failure to assess the stress-

corrosion-fracturing;

- ADD the descriptions for testing the plastic strain to failure;

- ADD the expression formula of the plastic strain to failure and the limitations

of the use of the formula;

- MODIFY the method of determining the critical stress or strain value;

- ADD the description of the test results;

- DELETE the contents of the original Appendix A;

- CHANGE the original Appendix B into Appendix A.

This part uses the redrafting methods to modify and adopt the ISO 7539-7.2005

Corrosion of metals and alloys - Stress corrosion testing - Part 7. Method for

slow strain rate testing.

As compared with ISO 7539-7.2005, this part has structural changes and adds

the clause 6.

The technical differences between this part and ISO 7539-7.2005 and their

reasons are as follows.

- ADJUST the relevant standards in the normative references, to adapt to

Chinese technical documents (see clause 2);

- MODIFY the definition of elongation to fracture, reduction of area, strain

rate, post-break elongation, part shrinkage and strain rate, to be consistent

with the definition given in GB/T 228.1-2010 (see clause 3);

- ADD the descriptions for the number of specimens per group, to clarify the

number of specimens and reduce the risk of use (see clause 5);

- ADD the requirements for the reagents, to provide a reproducible chemical

environment, thereby ensuring the consistent test results (see clause 6);

- ADD the requirements for the ratio of solution volume to specimen's surface

area, to ensure that the specimen is exposed to sufficient corrosive solution

Corrosion of metals and alloys - Stress corrosion

testing - Part 7. Slow strain rate testing

1 Scope

This part of GB/T 15970 specifies a slow strain rate test procedure, for studying

the susceptibility of metals and alloys to stress-corrosion-fracturing, including

hydrogen-induced failure.

The term "metal" as used in this part also includes alloys.

This part applies to boards, rods, wires, belts, tubes and their welded

assemblies.

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) are applicable to this standard.

GB/T 6682 Water for analytical laboratory use - Specification and test

methods

GB/T 15970.1 Corrosion of metals and alloys - Stress corrosion testing - Part

1 General guidance on testing procedures (GB/T 15970.1-1995, idt ISO

7539-1.1987)

GB/T 15970.4 Corrosion of metals and alloys - Stress corrosion testing - Part

4 Preparation and use of uniaxially loaded tension specimens (GB/T

15970.4-2000, idt ISO 7539-4.1989)

GB/T 15970.6 Corrosion of metals and alloys - Stress corrosion testing - Part

6 Preparation and use of pre-fractured specimens for tests under constant

load or constant displacement (GB/T 15970.6-2007, ISO 7539-6.2003, IDT)

3 Terms and definitions

The terms and definitions as defined in GB/T 15970.1 as well as the following

terms and definitions apply to this document.

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