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This standard is drafted in accordance with the rules given in GB/T 1.1-2020 Directives for standardization—Part 1: Rules for the structure and drafting of standardizing standards.
This standard is Part 1 of GB/T 3074. The following parts of GB/T 3074 have been published:
——GB/T 3074.1 The test method for flexural strength of carbon materials;
——GB/T 3074.2 Method for the determination of the elastic modulus of graphite electrodes;
——GB/T 3074.3 Method for the determination of the oxidation resistance of graphite electrodes;
——GB/T 3074.4 Method for the determination of the coefficient of thermal expansion (CTE) of graphite electrodes.
This standard replaces GB/T 3074.1-2008 Method for the determination of the flexure strength of graphite electrodes. In addition to a number of structural adjustments and editorial changes, the following main technical changes have been made with respect to GB/T 3074.1-2008:
——The scope has been modified (see Clause 1; Clause 1 of Edition 2008);
——The normative references have been modified (see Clause 2; Clause 2 of Edition 2008);
——The clause “Terms and definitions” has been added (see Clause 3);
——The principle of four-point load method has been added (see Clause 4.2; Clause 3 of Edition 2008);
——The apparatus have been modified (see Clause 5.1, 5.2, 5.3 and 5.4; Clause 4 of Edition 2008);
——The sample size and processing requirements have been modified (see Clause 6; Clause 5 of Edition 2008);
——The test procedures have been modified (see Chapter 7, Chapter 6 of Edition 2008);
—— The formulas for calculating flexural strength of parallelepiped test pieces have been added (see Section 8.2);
——The content of test report has been modified (see Chapter 9; Chapter 8 of Edition 2008);
This standard was proposed by China Iron and Steel Industry Association.
This standard is under jurisdiction of the National Technical Committee on Iron and Steel of Standardization Administration of China (SAC/TC 183).
The previous editions of this standard and standards replaced by this standard are as follows:
——It was first issued as GB/T 3074.1-1982 in 1982, first revised in 2008;
——This edition is the second revision.
Introduction
Carbon materials are widely used in steel, nonferrous metals, aerospace and other fields. Evaluating and judging the quality of carbon materials objectively and fairly plays an important role in enterprise development and trade demand. Its determination method is the basic means of quality characterization, and a reliable and consistent determination method is the guarantee of comparability of detection data.
In order to establish and improve the standard system of determination methods for facilitating quality control and characterization, the GB/T 3074 standard series were formulated. It is proposed to be composed of four parts in terms of the product performance of carbon materials. Part 1 The test method for flexural strength of carbon materials specifies the determination principle, apparatus, samples, test procedures, result calculation and test report of flexural strength of carbon materials, which is applicable to the determination of flexural strength of carbon materials by four-point load method at ambient temperature. Other standards specify the corresponding determination methods of carbon materials in terms of the other physical and chemical properties of carbon materials.
GB/T 3074 consists of the following four parts:
——GB/T 3074.1 The test method for flexural strength of carbon materials;
——GB/T 3074.2 Method for the determination of the elastic modulus of graphite electrodes;
——GB/T 3074.3 Method for the determination of the oxidation resistance of graphite electrodes;
——GB/T3074.4 Method for the determination of the coefficient of thermal expansion (CTE) of graphite electrodes.
This standard is Part 1 of GB/T 3074, which specifies the measuring methods for the flexural properties of carbon materials, and other standards specify the measuring methods for other physical and chemical properties.
The test method for flexural strength of carbon materials
1 Scope
This standard specifies the measuring principle, apparatus, samples, test procedures, result calculation and test report of flexural strength of carbon materials.
This standard is applicable to the determination of flexural strength of carbon materials by four-point load method at room temperature.
2 Normative references
The following documents contain provisions which, through reference in this text, constitute provisions of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced standard (including any amendments) applies.
GB/T 1427 Sample method of carbon material
GB/T 8170 Rules of rounding off for numerical values & expression and judgment of limiting values
3 Terms and definitions
No terms and definitions are listed in this standard.
4 Principle
4.1 Flexural strength is a measure of the maximum load that a material can bear when it is bent and broken by an external force. Its value is the normal stress on the cross section when the sample is bent and broken.
4.2 Four-point load method: Place the sample on two load-bearing blocks, and load them at their center until the sample breaks. The loads are evenly distributed at two points. The flexural strength is calculated according to the load on the sample when it breaks, the distance between the edge of the load and the supporting point, and the diameter (height and width) of the test sample.
5 Apparatus
5.1 Vernier caliper, with a measuring range of 0 mm~200 mm and an accuracy of 0.02 mm.
5.2 Micrometer, with a measuring range of 0 mm~50 mm and an accuracy of 0.01 mm.
5.3 Air drying oven equipped with automatic temperature adjustment device, with the temperature controlled at (110±5)°C.
5.4 Material testing machine: It is recommended that the maximum loading load of the sample shall be at least 5% ~ 90% of the sensor range, with the accuracy level no lower than Grade 1.
5.5 Test clamps: The clamps shall ensure that the force applied to the sample is normal without eccentricity by adjusting the spherical bearing seat or roller bearing assembly. The distance between the top and bottom indenters can be adjusted to meet the needs of samples of different sizes, and the clamps shall be equipped with a device to prevent the sample from sliding. The device is shown in Figure 1.
Foreword i
Introduction iii
1 Scope
2 Normative references
3 Terms and definitions
4 Principle
5 Apparatus
6 Samples
7 Test procedures
8 Result calculation
9 Test Report
