This standard is drafted in accordance with the rules given in the GB/T 1.1-2009.
This standard replaces GB/T 15711-1995 Steel Products — Method for Ecth Test of Tower Sample.
The following technical deviations have been made with respect to the GB/T 15711-1995 (the previous edition).
— standard name is changed to Inspection of Non-metallic Inclusions of Steel — Etching Test Method of Tower Samples;
— addition of reference to the rules of rounding off for numerical values and relevant requirements (see Clause 2, 5.2);
— addition of Clause 3 Terms and Definitions and the definition of hairlines (see Clause 3);
— modification of the number of samples, the number of samples is modified from "three samples are recommended if there is no specific requirements" to "one sample is recommended" (see 4.2; 3.2 in Edition 1995);
— addition of the requirements on the inspection of steel plates, and the sampling positions of flat steel plates and steel plates shall be determined by the purchaser and the supplier through consultation (see 4.3);
— addition of the length of step may be sampled according to the requirements of L1=60 mm, L2=72 mm, L3=90 mm (see Table 1, footnote a);
— Inspection rules are added (see Clause 5);
— addition of description on hairlines inspection (see Clause 5);
— addition of the requirement “If there are two hairlines on the same straight line of the test surface of the sample, and the distance between two hairlines is less than 0.6 mm, that shall be calculated as a hairline (see 6.3);
— addition of the requirements for test report shall be filled according to the requirements of the purchaser (see Clause 7);
This standard was proposed by the China Iron and Steel Association.
This standard is under the jurisdiction of the National Technical Committee on Iron and Steel of Standardization Administration of China (SAC/TC 183).
The previous editions of the standard replaced by this standard are as follows:
— GB/T 15711-1995.
Inspection of Non-metallic Inclusions of Steel — Etching Test Method of Tower Samples
1 Scope
This standard specifies the selection and preparation of test sample, hairlines inspection methods, expression and evaluation of test results and test report of etching test method of tower samples for inspection of non-metallic inclusions of steel.
This standard is applicable to the inspection of the number, length and distribution of hairlines in steel by etching test method for tower samples of steels with diameter, side length or thickness of 16 mm to 150 mm. Other products or specifications may be used as reference.
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 references, the latest edition of the referenced document (including any amendments) applies.
GB/T 226 Test Method for Macrostructure and Defect of Steel by Etching
GB/T 8170 Rules of Rounding Off for Numerical Values & Expression and Judgment of Limiting Values
3 Terms and Definitions
For the purposes of this document, the following terms and definitions apply.
3.1
hairlines
streaks formed by the extension of nonmetallic inclusions along the forging and rolling direction in the process of machining deformation in steel
4 Selection and Preparation of Test Samples
4.1 Sampling method
4.1.1 Tower samples are used in this standard. Unless otherwise specified in the product standard or special agreement, the applicable dimensions of steel tower hairline inspection shall be 16 mm ~ 150 mm in diameter, side length or thickness. Other products and specifications can be inspected through consultation between the purchaser and the supplier.
4.1.2 The samples shall be cut from steels (or billets) in the delivery state.
4.1.3 Samples shall be cut in a cold state. Hot saw, cold saw, flame cutting and shearing may be adopted for sampling. During sample processing, the deformation and heat-affected zone caused by sampling shall be removed.
4.2 Sampling quantity and position
The sampling quantity and position shall be in accordance with the corresponding product standard or special agreement. If no requirements specified in the product standard, it is recommended to take one sample of steel in the delivery state.
4.3 Preparation of samples
4.3.1 The inspection surface of the square or round steel samples as shown in Figure 1. The inspection surface of the flat or steel steel sample as shown in Figure 2. The specific sampling and sample preparation methods shall be determined through consultation between the purchaser and the supplier.
Dimensions in millimeters
Key:
D — diameter or side length of steels;
L — the length of each step;
D1 — the first step, 0.90D;
D2 — the second step, 0.75D;
D3 — the third step, 0.60D.
Figure 1 Tower Sample of Square Steel or Round Steel
Foreword II
1 Scope
2 Normative References
3 Terms and Definitions
4 Selection and Preparation of Test Samples
5 Test Methods
6 Expression and Evaluation of Test Results
