GB/T 2975-2018Steel and steel products - Location and preparation of samples and test pieces for mechanical testing (English PDF)

Foreword

This Standard is drafted in accordance with stipulations in GB/T 1.1-2009. This Standard serves as a replacement of GB/T 2975-1998 Steel and Steel Products - Location and Preparation of Test Pieces for Mechanical Testing. In comparison with GB/T 2975-1998, there are several main changes of technical content as follows:

---Specific requirement of sample designation is added (please refer to 4.2);

---The term "leg part" is modified into "flange"; the "waist part" is modified into "ventral shield" in section steel (please refer to A.2 in Version 1998);

---The requirement of sampling location of impact test piece along the thickness direction of flange of section steel is modified (please refer to Figure A.3 in Version 1998);

---The requirement of taking tensile billet sample of steel plate under the thickness of 25 mm <= t < 50 mm is deleted; the requirement of taking tensile billet sample of steel plate under the thickness of t >= 25 mm is unified (please refer to Figure A.10);

---The requirement of taking tensile billet sample of tempered or thermomechanical rolled (TMCP) steel plate is added (please refer to A.6.2.2 and footnote b of Figure A.10);

---The requirement of sampling location of impact billet of steel with thickness that is more than 40 mm is refined; optional requirements of sampling of steel plate under the thickness of 28 mm <= t < 40 mm are added (please refer to A.6.3 and Figure A.11; A.4.4 in Version 1998);

---The minimum thickness or diameter of steel products under machining allowance is modified from 20 mm into

12.5 mm; relevant content of "the selection of laser-cutting machining allowance" is increased (please refer to Appendix B). This Standard is modified in accordance with the re-drafting law and ISO 377.2017 Steel and Steel Products - Location and Preparation of Samples and Test Pieces for Mechanical Testing. In comparison with ISO 377.2017, there are several technical differences. Please see the technical differences and the causes for these differences below. Clauses that involve these differences are already indicated through longitudinal single line () in the blank of the outer margin.

---In terms of normative references, certain adjustment with technical differences is made in this Standard, so that it can adapt to the technical conditions in China. The condition of such adjustment is intensively reflected in Chapter 2 "Normative References". Please see the specific adjustment below. GB/T 15574, which adopts equivalent international standards, is applied as a replacement of ISO 6929 (please refer to Chapter 3); GB/T 20832, which adopts equivalent international standards, is applied as a replacement of ISO 3785 (please refer to Chapter 5.2).

---In order to make this Standard more operable and maintain consistency with the previous version of international standard, the requirement of sampling of section steel with slanted flange is refined (please refer to A.2.1.2);

---In accordance with the domestic application, the requirement of sampling of T- shaped steel is modified [please refer to Figure A.1c)];

---The requirement that "bending sample shall at least retain an original surface" is added to A.1.3 (please refer to A.1.3);

---General requirements, comprehensive stipulated tensile and impact sampling requirements are added to A.6.1; "the requirement that the direction and location of steel plate sampling shall be stipulated in product standard" is added to A.6.1;

1 Scope

GB/T 2975 specifies where in a steel product a test sample is taken from and how the test piece is prepared from it. It is one of the most frequently cited standards in the Chinese steel system, and the reason is that a tensile or impact result depends as much on where the piece came from as on the steel itself: the properties of a plate differ through its thickness and between its centre and its edge, those of a bar between surface and core, and those of a tube along and across the weld. The document fixes the sampling location for each product form, plate and strip, section, bar, wire rod, tube, forging and casting, the orientation of the test piece relative to the direction of rolling, the number of samples, the removal of the sample without altering its properties, and the machining of the test piece for the tensile, impact, bend, hardness and other mechanical tests. This is the clear-print edition. For a mill, a fabricator or a testing laboratory, this is what makes a certificate mean the same thing to both parties.

This Standard specifies the designation, sampling location and preparation requirements of mechanical testing of section steel, steel bar, steel wire rod, steel plate and steel pipe defined in GB/T 15574.

2 Normative References

The following documents are indispensable to the application of this Standard. In terms of references with a specified date, only versions with a specified date are applicable to this Standard. The latest version (including all the modifications) of references without a specified date is also applicable to this Standard.

GB/T 15574 Steel Products Classification ( GB/T 15574-2016, ISO 6929.2013, IDT)

GB/T 20832 Metallic Materials - Designation of Test Specimen Axes in Relation to Product Texture ( GB/T 20832-2007, ISO 3785.2006, IDT)

3 Terms and Definitions

The following terms and definitions, and the terms and definitions defined in GB/T 15574 are applicable to this document. Rough specimen is sample material that goes through machining and thermal treatment under proper circumstances for the preparation of sample. Reference condition refers to the condition of sample material, rough specimen or test piece after going through thermal treatment; it represents the ultimate expected condition of products.

4 General Requirements

Sample, rough specimen and test piece that are taken in accordance with Appendix A shall be deemed to be representative of the product.

5 Sample Preparation and Test Piece Selection

The selection of sample shall comply with the locations indicated in Appendix A. Sample shall be in a sufficient dimension, so that sufficient test pieces can be taken for stipulated test and necessary re-inspection. In accordance with the stipulation in product standard or contract, the conditions of sample can be divided into. Rough specimen used in test under reference condition shall be prepared in accordance with the following methods.

6 Test Piece Preparation

When thermal treatment under reference condition needs to be conducted on test piece, the thermal treatment condition shall be the same as the requirement of rough specimen [please refer to