This standard specifies the scope of application, reference standards, test principles, terms and definitions, specimens, test equipment and instruments, tests, test result processing and test reports of Charpy notch impact test for metal materials. This standard is applicable to the impact test of metal Charpy V-notch and U-notch specimens at temperatures between -192 and 1000°C. The impact test of other types of notches and unnotched specimens can refer to this standard. GB/T 229-1994 Metal Charpy notch impact test method GB/T229-1994 Standard download decompression password: www.bzxz.net

UDC:669 : 620.178.7
National Standard of the People's Republic of China
GB/T 229—1994
eqvs0 148 : 1983
ISO 83 : 1976
Metallic materials-Charpy notch impact test
Metallic materials-Charpy notch impact test1994-12-22 Issued
National Technical Supervision Bureau
1995-10-01 Implementation
National Standard of the People's Republic of China
Metallic materials-Charpy notch impact testGB/T 2291994
eqvs0 148 : 1983
ISO 83 1976
Replaces GB/T 229--84
GR 2106-80
GB 4159-84
This standard is equivalent to the international standards ISO148:1983 Charpy impact test for steel (V-notch) and ISO83:1976 Charpy impact test for steel (U-notch). In terms of scope of application, specimen size tolerance, test operation and high and low temperature impact test conditions, this standard is more detailed than the international standards, and adds references for determining the ductile-brittle transition temperature. 1 Subject content and scope of application
This standard specifies the scope of application, reference standards, test principles, terms and definitions, specimens, test equipment and instruments, tests, test result processing and test reports of Charpy notch impact test for metallic materials. This standard is applicable to impact tests of metal Charpy V-notch and U-notch specimens in the temperature range of -192 to 1000℃. This standard can be used as a reference for impact tests of other types of notched and unnotched specimens. 2 Reference standards
GB2975 Sampling regulations for mechanical and process performance tests of steel materialsGB3808 Pendulum impact testing machine
Rules for numerical rounding
GB 81701
GB10623 Terminology for mechanical performance tests of metals
GB/T 12778 Method for determining the impact fracture of thick metalsJJG 13G Verification procedures for working glass liquid thermometersVerification procedures for working platinum 10-platinum thermocouples
JJG141
JJG 145
Verification procedures for pendulum magnesium impact testing machine
JG351 Verification procedures for working nickel-chromium-silicon and nickel-chromium-copper steel thermocouplesJJG 368 Working-Constantan Thermocouple Verification Procedure 3 Test Principle
Use a pendulum of specified height to strike the notched specimen in the state of simply supported beam once, and measure the impact absorption energy when the specimen breaks. 4 Terms and Definitions
This standard mainly uses the following terms:
Impact absorption energy
Brittle fracture rate
Impact absorption energy-temperature curve
Ductile-brittle transition temperature
The definitions of these terms are given in GB10623.
National Technical Supervision Week 1994-12-22 Approved 1995-10-01 Implementation
5 Test specimen
GH/T229—1994
5.1 The selection of impact specimens shall be carried out in accordance with the product standards or the provisions of GB2975. 5.2 The preparation of the specimen should avoid the impact properties of the metal being affected by work hardening or overheating. 5.3 The shape and size of the standard Charpy notch impact specimen are shown in Figures 1, 2 and 3. 55±0.60
Standard Charpy type notch
27.610.30
Figure 2 Standard Charpy U-notch impact test bar with a notch depth of 2 mm 0.025
275±0.30bzxz.net
GB/T 229-1994
Figure 3 Standard Charpy U-notch impact specimen with notch depth of 5mm Note: According to relevant standards or mutual agreement, the specimen can retain one or two rolling surface marks, and the notch axis should be perpendicular to the rolling surface. ② For the specimen positioned in a hurry, the specimen length tolerance should be 55+0.10mm, the distance from the notch centerline to the end face should be 27.5±0.05mm, the end face grain roughness parameter Ra should not be greater than 3.2um, and the end face should be perpendicular to the side of the specimen. 5.4 The notch of the specimen should be smooth. For arbitration tests, the surface roughness parameter Ra of the notch bottom should not be greater than 1.6um. 5.5 If it is not possible to prepare a standard specimen, a small-sized specimen with a width of 7.5mm or 5.mm can be used. The other dimensions and diameter of the specimen are opposite to the standard specimen with the corresponding notch. The notch should be opened on the narrow side of the specimen. 5.6 The position of the test mark should not affect the support and positioning of the specimen, and should be as far away from the notch as possible. 6 Test equipment and instruments
6.1 The standard impact energy of the impact test machine is 300J (±10J) and 150J (±10J). The impact speed of the pendulum at the moment of impact should be 5.0~5.5m/s. If necessary, other impact energy test machines can also be used. 6.2 The specimen support and pendulum blade dimensions of the test machine shall comply with the provisions of Figure 4. GB/T 229-1994
Figure 4 Specimen support and pendulum chain blade
R1-1,5
6.3 Other technical conditions of the impact test machine shall comply with the provisions of GB3808 and shall be regularly calibrated according to JJG145. 6.4 For high temperature or low temperature impact tests, the temperature control device shall be able to stabilize the test temperature within ±2℃ of the specified value. 6.5 When using liquid medium to heat or cool the sample, the thermostat should have sufficient capacity and medium, and should have a device to make the medium temperature uniform. 6.6 The minimum scale value of the glass thermometer used for temperature measurement should not be greater than 1°C, and the error should comply with the provisions of JJG 130. The temperature measuring thermocouple should comply with the requirements of Class I thermocouple in JJG 141, JJG 351 or JJG 368. 6.7 The error of the temperature measuring instrument (digital indicating device or potentiometer) should not exceed ±0.1%. 6.8 The temperature of the reference end of the thermocouple should be kept constant, and the deviation should not exceed ±0.5°C. 7 Test
7.1 The room temperature impact test should be carried out at 10~35°C, and the test with strict test temperature requirements should be carried out at 20±2°C. 7.2 The impact test machine is generally used within the range of 10%~90% of the maximum energy of the pendulum. 7.3 Before the test, the return-to-zero error of the passive pointer when the pendulum chain is empty should be checked. The return-to-zero error should not exceed one-fourth of the minimum scale value. 7.4 The minimum scale value of the measuring tool for checking the sample size should not be greater than 0.02mm. 7.5 The sample should be placed close to the support, and the back of the sample notch should face the pendulum blade. The symmetric surface of the sample notch should be located on the symmetric surface of the two supports, and its deviation should not be greater than 0.5mm.
7.6 For the high-overflow impact test with end face positioning, the positioning mechanism should be adjusted according to the expansion of the sample, and the expansion is calculated as follows: A = 27. 5 X a(t - ta)
Where: A—expansion of half the length of the sample, m, α——linear expansion coefficient of the sample at the test temperature, 1/℃t-test temperature, ℃,
tn—room temperature, ℃.
7.7 In high-temperature or low-temperature impact tests, various methods can be used to heat or cool the sample. The test medium should be safe, non-toxic, and non-corrosive to metals. The following media are recommended:
Test temperature, ℃
200~～>35
0～-70
70~—105
—105~—192
GB/T 229-1994
Air heating
High temperature oil
Water+ice
Ethanol+dry ice
Anhydrous ethanol+liquid nitrogen
7. 8 The sample should be kept at the specified temperature for a sufficient time. When using liquid media, the overflow time should be no less than 5 minutes: When using gas media, the heat preservation time should be no less than 20 minutes.
7.9 When removing the sample, the temperature of the fixture should be as close as possible to the medium temperature. 7.10 The time from the sample being removed from the liquid medium to being struck should be within 28 seconds, and the time from the sample being removed from the gas medium device to being struck should be within 1 second:
If the above requirements cannot be met, the sample must be interrupted within 3 to 5 seconds. At this time, the temperature loss should be compensated by using the method of supercooling or overheating the sample. The degree of supercooling or overheating can refer to Appendix A (reference). For high temperature tests, the effect of overheating on material properties should be fully considered. 7.11 Determination of ductile-brittle transition temperature
For metal materials with low-temperature brittleness, their ductile-brittle transition temperature can be determined by a series of temperature shock tests. The determination method can be found in Appendix B (reference).
8 Test result processing
8-1 The impact absorption energy should retain at least two significant digits, and the rounding method should be implemented in accordance with GB8170. 8.2 If the specimen is not completely broken due to insufficient impact energy of the testing machine, the greater than symbol "" should be added before the test data. In other cases, "not broken" should be noted.
8.3 The test results of specimens of different types and sizes cannot be directly compared and converted. 8.4 If there are visible cracks or defects on the fracture of the specimen after the test, it should be noted in the test report. 8.5 If any of the following situations occurs during the test, the test results are invalid: Misoperation:
The hammer is stuck when the specimen is broken.
9 Test report
The test report should include the following contents:
National standard number:
Type and mark of test material;
Specimen size and type,
Test temperature:
Strike energy of testing machine;
Impact absorption energy:
Impact absorption energy of V-notch test
Impact absorption energy of U-notch specimen with a depth of 2mm; Impact absorption energy of U-notch specimen with a depth of 5mm; Ductile-brittle transition temperature (if necessary):
Test date.
GB/T229.—1994
Appendix A
Temperature compensation when the sample is removed from the constant temperature device and interrupted within 3~5$ (reference)
Test temperature,
Test temperature
400~500
-9000-1
Appendix B
Determination of ductile transition temperature
(reference)
The ductile-brittle transition temperature is generally determined using a standard Charpy √-type notch punching specimen. H
Supercooling temperature,
Superheating temperature: 0
40--50
According to the impact test results at the same temperature, the B2
auxiliary line is drawn with the impact absorption or brittle fracture rate as the ordinate and the test temperature as the coordinate. As shown in Figure B1.
B3 Each test temperature is generally tested with the main specimen. The interval and test points of the test temperature should ensure that a complete and clear curve is drawn. B4 According to relevant standards or mutual agreement, the ductile-brittle transition temperature can be determined by the following methods: a. The temperature corresponding to the specified percentage (n) between the upper and lower platforms of the
impact absorption energy-
temperature curve is represented by EITn (for example, the temperature corresponding to 50% of the upper and lower platforms of the impact absorption energy is recorded as TT5). b. The temperature corresponding to the specified brittle section rate (r) in the
-temperature curve is represented by FATTn (for example, the temperature corresponding to 0% of the brittle section rate is recorded as FATTs). The temperature corresponding to the lateral expansion value between the upper and lower platforms of the
temperature curve is represented by LETT. B5 The brittle section rate and lateral expansion value are determined according to GB/T12778. GB/T 229 -1994
B6 The ductile-brittle transition temperature determined by different methods cannot be compared with each other.
Test quality, C
Cold market warm-up
Figure B1r Schematic diagram of ductile-brittle transition temperature curve
Additional instructions:
This standard is proposed by the Ministry of Metallurgical Industry of the People's Republic of China. This standard is under the jurisdiction of the Information Standards Research Institute of the Ministry of Metallurgical Industry. The main drafters of this standard are Ji Jiulin and Liang Xinbang. The level of this standard is marked GB/T229-94Y0
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