GB/T 229-2020 in English

《GB/T 229-2020金属材料 夏比摆锤冲击试验方法》由TC183（全国钢标准化技术委员会）归口，TC183SC4（全国钢标准化技术委员会力学及工艺性能试验方法分会）执行，主管部门为中国钢铁工业协会。

This standard is developed in accordance with the rules given in GB/T 1.1-2009.

This standard replaces GB/T 229-2007 Metallic materials - Charpy pendulum impact test method, and the following main technical changes have been made with respect to GB/T 229-2007:

- notch-free test pieces are added in the scope, and requirements are made for terms and definitions, symbols and interpretation, dimensional deviation and test piece installation (see Clause 1, 3.2.1, Table 1, Table 2, 8.1 and Annex A);

- some of the terms and definitions are modified and added (see 3.1.3, 3.2.1, 3.2.2 of this standard, and 3.2.1 and 3.2.2 of 2007 edition);

- symbol B of sample thickness, angle symbol α when pendulum is released, explanation of angles of rise β1 and β2, symbol KN of nominal initial potential energy, symbol M of torque, symbol ρ of energy loss caused by pointer friction, symbol ρ' of energy loss caused by bearing friction and air resistance, and correction symbol ρβ of energy loss caused by angle of rise β are added, and symbol of shear fracture appearance is changed to SFA. The symbol of transition temperature symbol Tt27 corresponding to the specified absorbed energy value of 27 J, transition temperature symbol Tt50% us corresponding to 50% absorbed energy of the upper shelf, transition temperature symbol Tt50%SFA corresponding to 50% shear fracture and transition temperature symbol Tt0.9 corresponding to lateral expansion 0.9 mm are added (see table 1 of this standard, and that of 2007 edition);

- the principle of impact test is added (see Clause 5 of this standard and Clause 5 of 2007 edition);

- the determination of friction loss is added (see 8.2);

- the requirements of test temperature are added (see 8.3.3 of this standard, and 8.2.3 of 2007 edition);

- mandatory information and optional information are added in the test report [see 9.1 g), 9.2 j) and k)];

- informative Annex E “Measurement uncertainty of an absorbed energy value, K” (see Annex E) is added;

- the informative Annex about high temperature or low temperature compensation value is deleted (see Annex E of 2007 edition).

This standard has been redrafted and modified in relation to IEC 148-1:2016 Metallic materials - Charpy pendulum impact test - Part 1: Test method

Compared with ISO 148-1: 2016, there are structural differences in this standard, with 8.9 test results added.

There are some technical differences between this standard and ISO 148-1:2016, which are marked with perpendicular single line (｜) in the outside page margin of the provisions concerned.

The technical differences and their causes are as follows:

—— In Clause 1, notch-free test pieces are added to adapt to China's national conditions;

——the adjustments of technical differences are made for the normative references in this standard so as to adapt to the technical conditions of China. The adjustments are mainly reflected in Clause 2 "Normative references", which are shown in the following:

 ISO 148-2 is replaced by GB/T 3808, which is modified in relation to the international standard (see 7.2 and E.2.1.2);

 GB/T 2975 is added for reference (see 6.4);

 GB/T 8170 is added for reference (see 8.9);

 JJG 145 is added for reference (see 7.2);

 ISO 268-1 is deleted (see Table 2 of ISO 148 -1).

- The symbol KT and its interpretation missing in ISO standard are added in Table 1, and the symbol and interpretation of notch-free test pieces are correspondingly as notch-free test pieces are added in the scope. The unit of β1 and β2 is defined as "°", and the unit of K1, K2 and KN is defined as "J" to avoid confusion.

- the last two paragraphs of Clause 5 are changed to notes, because they further explain the principle;

- “And test pieces with other thicknesses may also be used upon agreement.” is added in 6.1.2 to expand the applicable scope of this standard;

 
- “The samples shall be cut according to relevant product standards or GB/T 2975.” is added in 6.4 to facilitate practical operation;

- in Table 2, the dimensions and tolerances of U-notch test piece with ligament width of 8 mm are added, the notes of notch-free test pieces were added, the included angle tolerance between adjacent longitudinal faces of test pieces is adjusted, and the tolerance grades of two kinds of notches are deleted to meet the national conditions of China;

- for the convenience of application, the symbols KW2 and KW8 for the striking edge of the notch-free test piece pendulum are added in 7.3;

- for the convenience of operation of notch-free test pieces, the provisions on the installation position of notch-free test pieces and the inspection before the test are added in 8.1;

- the detailed requirements on bearing friction and wind resistance loss are added in 8.2.2 for the implementation of this standard;

- the requirements of the lower limit of use and resolution of the testing machine are added in 8.5, and Note 2 is added to explain, so as to increase the operability of the standard and facilitate the implementation of this standard;

- the explanation “If the pendulum does not break the sample, and the measured absorbed energy exceeds the energy range of the testing machine due to insufficient impact energy of the testing machine” is added in 8.6 to increase the operability of this standard.

- the rounding off requirements of absorbed energy is added in 8.9, and increase the operability of this standard;

- c) notch type and ligament width (notch depth) is added in 9.1, and the requirements of sample size expression are added in d) to increase the operability of this standard;

- in Annex A, the sentence "self-centring tongs with thickness of 5 mm and 3 mm” are deleted due to data error; and the requirements of tongs for notch-free test pieces and U-notch tongs are added to increase the operability of this standard and facilitate the implementation of this standard.

The following editorial changes have been made in this standard:

- the standard name is changed;

- the expression "the letter W is used to indicate notch-free test piece" is added in the note of 3.1.2.

This standard was proposed by 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 standard replaced by this standard are as follows:

——GB/T 229-1984, GB/T 229-1994, GB/T 229-2007.


Metallic materials - Charpy pendulum impact test method

1 Scope

This standard specifies the Charpy (V-notch and U-notch) pendulum impact test method for determining the energy absorbed in an impact test of metallic materials.

This standard is applicable to Charpy pendulum impact test at room temperature, high temperature or low temperature, but does not cover instrumented impact testing, which is specified in GB/T 19748.

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 2975 Steel and steel products - Location and preparation of samples and test pieces for mechanical testing (GB/T 2975-2018, ISO 377:2017, MOD)

GB/T 3808 Verification of pendulum-type impact testing machines (GB/T 3808-2018, ISO 148-2: 2008, MOD)
GB/T 8170 Rules of rounding off for numerical values & expression and judgment of limiting values
JJG 145 Verification regulation of pendulum impact testing machines

3 Terms and definitions

For the purposes of this document, the following terms and definitions apply.

3.1 Definitions pertaining to energy

3.1.1
initial potential energy
potential energy
Kp
potential energy of the pendulum hammer prior to its release for the impact test, as determined by direct verification

3.1.2
absorb energy
K
energy required to break a test piece with a pendulum impact testing machine, after correction for friction

Note: The letter V or U is used to indicate the notch geometry, the letter W is used to indicate notch-free test piece. The number 2 or 8 is used as a subscript to indicate the radius of the striker, for example KV2.

3.1.3
nominal initial potential energy
nominal energy
KN
energy assigned by the manufacturer of the pendulum impact testing machine

3.2 Definitions pertaining to test piece

3.2.1
width
W
distance between the notched face and the opposite face

Note 1: For notch-free test piece, it is the distance between the surface where the strike center is located and its opposite surface.

Note 2: See Figure 1.

Note 3: In GB/T 229-2007, the distance between the notched face and the opposite face was specified as “height”. Changing this dimension to “width” makes this standard consistent with the terminology used in other fracture standards.

3.2.2
thickness
B
dimension perpendicular to the width and parallel to the notch

Note 1: For notch-free test piece, it is the minimum dimension perpendicular to the width direction.

Note 2: See Figure 1.

Note 3: In GB/T 229-2007, the dimension perpendicular to the width direction and parallel to the notch axis was specified as “width”. Changing this dimension to “thickness” makes this standard consistent with the terminology used in other fracture standards.

3.2.3
length
L
largest dimension perpendicular to the notch

Note 1: For notch-free test piece, it is the maximum dimension perpendicular to the width direction.

Note 2: The notch direction is the notch depth direction, as shown in Figure 1.



Key

1——anvil; 4——shroud; 7——thickness of test piece, B;
2——standardized test piece; 5——width of test piece, W; 8——centre of strike;
3——test piece supports; 6——length of test piece, L; 9——direction of pendulum swing.

Note: The shroud may be used in U-shaped pendulum testing machine to protect the broken test piece from rebounding to the pendulum and jamming.

Figure 1 Relative position of test piece to the supports and anvils of a pendulum impact testing machine

4 Symbols and interpretations

The symbols and interpretations applicable to this standard are indicated in Table 1.

 
Table 1 Symbols, designation and unit
Symbol Unit Designation
B mm thickness of test piece
α ° angle of fall of the pendulum
β1 angle of rise in the fall of the pendulum without a test piece in position
β2 angle of rise in the fall of the pendulum without a test piece in position and without resetting the indication mechanism
L mm length of test piece
LE mm lateral expansion
K J absorbed energy (expressed as KV2, KV8, KU2, KU8, to identify specific notch geometries and the radius of the striking edge)
J indicated absorbed energy in the fall of the pendulum without a test piece in position
K2 J indicated absorbed energy in the fall of the pendulum without a test piece in position and without resetting the indication mechanism
KN J nominal initial potential energy
Kp J initial potential energy (potential energy)
KT J total absorbed energy
KV2 J absorbed energy for a V-notch test piece using a 2 mm striker
KV8 J absorbed energy for a V-notch test piece using a 8 mm striker
KU2 J absorbed energy for a U-notch test piece using a 2 mm striker
KU8 J absorbed energy for a U-notch test piece using a 8mm striker
KW2 J absorbed energy for a notch-free test piece using a 2 mm striker
KW8 J absorbed energy for a notch-free test piece using a 8mm striker
M N·m moment equal to the product F·l2
ρ J absorbed energy loss caused by pointer friction
ρ′ J absorbed energy loss caused by bearing friction and air resistance
ρβ J correction of absorbed energy losses for an angle of rise β
SFA % shear fracture appearance
Tt ℃ transition temperature
W mm width of test piece
Tt27 ℃ transition temperature defined at a specific value of absorbed energy; for example, 27 J
Tt50%US ℃ transition temperature defined at a particular percentage of the absorbed energy of the upper shelf; for example, 50 %
Tt50%SFA ℃ transition temperature defined at a particular proportion of shear fracture; for example, 50 %
Tt0.9 ℃ transition temperature defined at a particular amount of lateral expansion; for example, 0.9 mm

 
5 Principles of the test

This test consists of breaking a test piece with a single blow from a swinging pendulum, under the conditions defined in Clauses 6, 7 and 8. The notch in the test piece has a specified geometry and is located in the middle between two supports, opposite to the location which is impacted in the test. The energy absorbed in the impact test, the lateral expansion and the shear fracture appearance are normally determined. Because the impact values of many materials vary with temperature, tests shall be carried out at a specified temperature. When this temperature is other than ambient, the test piece shall be heated or cooled to that temperature, under controlled conditions.

Note 1: The Charpy pendulum impact test is often used in routine, high-throughput pass/fail acceptance tests in industrial settings. For these tests, it may not be important whether the test sample is completely broken, partially broken, or simply plastically deformed and dragged through the anvils. In theoretical research, the measured energy values shall be studied in more detail, in which case it can be highly relevant whether the sample is broken or not.

Note 2: It is important to note that not all Charpy pendulum impact test results can be directly compared. For example, the test can be performed with hammers having strikers with different radii, or with different test piece shapes. Tests performed with different strikers can give different results.[2] This is why not only the adherence to this standard but also a clear and complete reporting of the type of instrument, the test piece and the details of the post-test test pieces are crucial for comparability of results.

Foreword I
1 Scope
2 Normative references
3 Terms and definitions
3.1 Definitions pertaining to energy
3.2 Definitions pertaining to test piece
4 Symbols and interpretations
5 Principles of the test
6 Test pieces
6.1 General
6.2 Notch geometry
6.3 Tolerance of the test pieces
6.4 Preparation of the test pieces
6.5 Marking of the test pieces
7 Test equipment
7.1 General
7.2 Installation and verification
7.3 Striker
8 Test procedure
8.1 General
8.2 Friction measurement
8.3 Test temperature
8.4 Specimen transfer
8.5 Machine capacity
8.6 Incomplete fracture
8.7 Test piece jamming
8.8 Post-fracture inspection
8.9 Test result
9 Test report
9.1 Mandatory information
9.2 Optional information
Annex A (Informative) Self-centring tongs
Annex B (informative) Lateral expansion
Annex C (Informative) Fracture appearance
Annex D (Informative) Absorbed energy vs. temperature curve and the transition temperature
Annex E (Informative) Measurement uncertainty of an absorbed energy value, K
Bibliography