This standard is developed in accordance with the rules given in GB/T 1.1-2009.
This standard replaces GB/T 2975-1998 Steel and steel products — Location and preparation of samples and test pieces for mechanical testing in whole. The following technical changes have been made with respect to GB/T 2975-1998:
——The specific requirements of the sample identification are added (see Subclause 4.2);
——The “leg” is changed into “flange”, the “midland” into “web” in the terms of steel section. (see Subclause A.2; Subclause A.2 in 1998 Edition;
——The location requirements of impact testing piece in the thickness of steel section flange is modified (see Figure A.3; Figure A.3 in 1998 Edition);
——The requirement for tensile rough specimen of steel plates with the thickness of at 25 mm ≤ t < 0 mm is deleted, the requirement for tensile rough specimen at the thickness of t ≥ 25 mm is unified (see Figure A.10);
——The requirement for tensile rough specimen of steel plate quenched and tempered or rolled in thermo mechanical control process (TMCP) is added (see Subclause A.6.2.2 and footnote b of Figure A.10).
——The location requirement of impact rough specimen at the thickness of greater than 40 mm steel plates is refined, and the selected requirement at the thickness of 28 mm ≤ t < 40 mm is added (see A.6.3 and Figure A.11; SubclauseA.4.4 in 1998, Edition);
——The minimum thickness and diameter of the machining allowance of the steel products will be changed from 20 mm to 12.5 mm, and the corresponding content -“selection of the laser cutting machining allowance“ is added. (see Annex B).
This standard has been redrafted and modified in relation to International Standard ISO 377: 2017 Steel and steel products—Location and preparation of samples and test pieces for mechanical testing.
Technical deviations, together with their justifications between this standard and ISO 377:2017 are as follows (The terms involved in these differences have been indicated with a vertical single line (|) at the outer margin).
——The adjustments of technical difference are made for the normative references in this standard so as to adapt to the technical conditions in China. The adjustment is mainly reflected in Clause 2 "Normative references" with the specific adjustments as follows:
GB/T 15574 identical to the international standard is used to replace ISO 6929 (see Clause 3);
GB/T 20832 identical to the international standard is used to replace ISO 3785 (see Subclause 5.2);
——In order to make this standard more operational, consistent with the previous version of the national standard, the requirements for the steel section with a slope flange are refined (see Subclause A.2.1.2);
——The sampling requirements of T-section steel is changed, based on the domestic application [see Figure A.1c)];
——The requirement of “Bend test piece shall reserve a previous surface” is added in the A.1.3 (see Subclause A.1.3);
——Subclause A.6.1 “General requirement” is added, the sampling requirement of tensile and impact is specified comprehensively: “the direction and location of test piece at steel plates shall be specified in the product standard".
——The requirement for test piece of rolled steel plates is added (see Subclause A.6.1.3).
For convenience of use, this standard includes the following editorial changes:
——To keep consistent with the symbol in the Figure, the symbol "T" for wall thickness in (Subclause A.1) is changed to "t";
——Annex B “Selection of rough specimen machining allowance” is added.
This standard was proposed by the China Iron and Steel Association.
This standard is under the jurisdiction of SAC/TC 183 National Technical Committee on Iron and Steel of Standardization Administration of China.
The previous editions of this standard are as follows:
——GB/T 2975-1993, GB/T 2975-2008.
Steel and steel products — Location and preparation of samples and test pieces for mechanical testing
1 Scope
This document specifies requirements for the identification, location and preparation of samples and test pieces intended for mechanical tests on steel sections, bars, rod, flat products and tubular products as defined in GB/T 15574.
This standard is applicable to sampling and preparation of test pieces for mechanical testing of steel and steel products. If agreed in the order, this document can also apply to other metallic products. These samples and test pieces are carried out in conformity with the methods specified in the product standard, material standard or testing standard.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated reference, the latest edition (including all the amendments) applies.
GB/T 15574 Steel products Vocabulary (GB/T 15574-2006, ISO 6929: 2013, NEQ)
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
For the purpose of this standard, the terms and definitions specified in GB/T 15574 as well as the followings apply.
3.1
test unit
number of pieces or the tonnage of products to accept or reject together, on the basis of the verification tests carried out on sample products in accordance with the requirements of the product standard or order.
Note: see Figure1.
3.2
sample product
item (e.g. bar, sheet, coil) selected from test unit for inspection or testing.
Note: see Figure1.
3.3
sample
sufficient quantity of material taken from the sample product for the purpose of producing one or more test pieces.
Note 1: see Figure1.
Note 2: in certain cases, the sample can be the sample product.
3.4
rough specimen
part of a sample having undergone mechanical treatment, for the purpose of producing a test piece
Note: see Figure1.
3.5
test piece
part of a sample or rough specimen, with specified dimensions, machined or unmachined, brought to a required condition for submission to a given verification test.
Note 1: see Figure1.
Note 2: in certain cases, the test piece can be the sample or the rough specimen.
3.6
reference condition
condition of a sample, rough specimen or test piece having undergone a heat treatment to represent the intended final condition of the product.
Note: in such cases, the sample, rough specimen or test piece is called the reference sample, reference rough specimen or reference test piece.
Key:
1——test unit (Subclause 3.1);
2—— sample product (Subclause 3.2);
3—— sample (Subclause 3.3);
4——rough specimen (Subclause 3.4);
5——test piece (Subclause 3.5);
Figure 1 Examples of terms defined in Clause 3.
4 General requirements
4.1 Representative testing
Sample, rough specimens and test pieces selected in accordance with Annex A shall be considered to be representative of the product.
Note: as a result of their production sequence, e.g. melting, casting hot or cold forming or both, heat treatment, etc., steel products are not homogeneous. The mechanical properties of samples taken from other locations can be different.
4.2 Identification of sample products, samples, rough specimens and test pieces
4.2.1 Sample products, samples, rough specimens and test pieces shall be marked to ensure traceability to the original product and their location and orientation in that product. For this purpose, if, during the preparation of any one or more of the samples, rough specimens or test pieces, removal of the marks cannot be avoided, transfer of these marks shall be carried out before the existing marks are removed. In the case of specific inspection and where requested by the purchaser, the transfer of the marks shall be carried out in the presence of the purchaser’s representative.
4.2.2 In the case of fully automatic in line preparation and testing systems, marking of samples, rough specimens and test pieces is not necessary if an adequate control system exists, which defines the procedures to follow in the event of system failure.
5 Preparation of samples and selection of test pieces
5.1 Selection and dimensions of samples and location of test pieces
The sample shall be selected so that the test piece can be located as indicated in Annex A. The sample shall have sufficient dimensions to allow sufficient test pieces required for carrying out specified tests, and for any retests that are necessary.
5.2 Direction of axis of test pieces
The direction of the test piece axis relative to the principle direction of working shall be as specified in the appropriate product standard or order. The designation of the test piece axis shall be in accordance with GB/T 20832.
5.3 Condition and separation of samples
5.3.1 General
The material or product standard shall specify whether the test is intended to determine the properties:
a) In the as-delivered condition (see Subclause 5.3.2);
b) In the reference condition (see Subclause 5.3.3).
5.3.2 Testing in the as-delivered condition
5.3.2.1 A sample intended for testing in the as-delivered condition shall be separated from the product either:
a) After the forming or heat treatment processes or both have been completed;
b) Before the heat treatment process, in which case the heat treatment of the separated sample shall be carried out under the same conditions as that of the product.
5.3.2.2 Separation of the sample shall be carried out in such a manner so as not to change the characteristics of that part of the sample used to provide the test pieces. If flattening or straightening of the sample is unavoidable in the preparation of the test piece, the flattening or straightening shall be carried out cold unless otherwise specified in the product standard.
5.3.3 Testing in the reference condition
5.3.3.1 Sample
5.3.3.1.1 A sample intended for testing in the reference condition shall be separated from the product at the stage of manufacture specified in the product standard or order.
5.3.3.1.2 Separation of the sample shall be carried out in such a manner so as not to change the characteristics of that part of the sample used to provide the test pieces after heat treatment. Flattening or straightening, if necessary, can be carried out either hot or cold before any heat treatment. When carried out hot, it shall be at a temperature below the final heat treatment temperature.
5.3.3.2 Rough specimen
A rough specimen intended for testing in the reference condition shall be prepared as follows:
a) Mechanical treatment prior to heat treatment: when the sample is made smaller for the process of heat treatment, the product standard shall specify the dimensions to which the rough specimen shall be reduced and the reduction process e.g. forging, rolling, machining.
b) Heat treatment: the heat treatment of the rough specimen shall take place in an environment where the uniformity of the temperature is adequately ensured and the temperature is measured by means of a calibrated instrument. The heat treatment shall be in accordance with the requirements of the product standard or of the order.
6 Preparation of test pieces
6.1 Cutting and machining
Cutting and machining of samples and rough specimens for the preparation of test pieces shall be carried out taking such precautions as necessary to avoid superficial work hardening and heating of the material likely to change the mechanical characteristics. The machining allowance sampling by burnt-cutting and cold shearing may refer to Annex B. After machining, any marks left by the tool that can interfere with the results of the test shall be removed, either by grinding (with ample coolant supply) or by polishing. Provided that the chosen method of finishing maintains the dimensions and shape of the test piece within the tolerances specified in the standard for the appropriate test. The tolerances on the dimensions of the test pieces shall be those specified in the standards for the appropriate test methods.
6.2 Reference heat treatment
When the required reference heat treatment is being carried out on the test piece, the provisions for heat treatment shall be the same as for the rough specimen [see Subclause 5.3.3.2 b)].
Foreword i
1 Scope
2 Normative references
3 Terms and definitions
4 General requirements
5 Preparation of samples and selection of test pieces
6 Preparation of test pieces
Annex A (Normative) Location of test pieces and samples
Annex B (Informative) Selection of rough specimen machining allowance
