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Delivery: <= 4 days. True-PDF full-copy in English will be manually translated and delivered via email. GB/T 19748-2019: Metallic materials - Charpy V-notch pendulum impact test - Instrumented test method Status: Valid GB/T 19748: Historical versions
Basic dataStandard ID: GB/T 19748-2019 (GB/T19748-2019)Description (Translated English): Metallic materials - Charpy V-notch pendulum impact test - Instrumented test method Sector / Industry: National Standard (Recommended) Classification of Chinese Standard: H22 Classification of International Standard: 77.040.10 Word Count Estimation: 22,237 Date of Issue: 2019-08-30 Date of Implementation: 2020-07-01 Older Standard (superseded by this standard): GB/T 19748-2005 Quoted Standard: GB/T 229; GB/T 3808 Adopted Standard: ISO 14556-2015, MOD Issuing agency(ies): State Administration for Market Regulation, China National Standardization Administration Summary: This standard specifies the terms and definitions, principles, samples, test equipment and instruments, test procedures, evaluation and processing of test results, and test reports of the instrumented test methods for Charpy V-notch pendulum impact testing of metallic materials. This standard applies to the determination of the impact properties of the instrumented Charpy V-notch pendulum of metal materials. Compared with GB/T 229 Charpy pendulum impact test method, this standard specifies more abundant product-related fracture information than ordinary impact test. U-notch samples can also refer to this standard. General information on instrumented impact testing can be found in [3-8]. GB/T 19748-2019: Metallic materials - Charpy V-notch pendulum impact test - Instrumented test method---This is a DRAFT version for illustration, not a final translation. Full copy of true-PDF in English version (including equations, symbols, images, flow-chart, tables, and figures etc.) will be manually/carefully translated upon your order. Metallic materials - Charpy V-notch pendulum impact test - Instrumented test method ICS 77.040.10 H22 National Standards of People's Republic of China Replace GB/T 19748-2005 Charpy V-notch pendulum impact test for metallic materials Instrumented test method 2019-08-30 released 2020-07-01 implementation State Administration for Market Regulation Issued by China National Standardization Administration Table of contentsPreface Ⅲ 1 Scope 1 2 Normative references 1 3 Terms and definitions 1 4 Symbols and description 3 5 Test principle 4 6 Test equipment and instruments 4 7 Sample 6 8 Test procedure 6 9 Evaluation and processing of test results 6 10 Test report 8 Appendix A (informative appendix) The design of instrumented impact blade 9 Appendix B (informative appendix) Example of a 2mm radius hammer blade calibration support block 10 Appendix C (Normative Appendix) Instrumented Charpy V-notch Pendulum Impact Test for Small Samples 11 Appendix D (informative appendix) Formula 16 for estimating ductile section rate Reference 17ForewordThis standard was drafted in accordance with the rules given in GB/T 1.1-2009. This standard replaces GB/T 19748-2005 "Steel Charpy V-notch pendulum impact test instrumental test method", and Compared with GB/T 19748-2005, the main technical changes are as follows. ---The standard name is revised from "Charpy V-notch Pendulum Impact Test Instrumental Test Method for Steel" to "Charpy for Metallic Materials" Instrumented test method for V-notch pendulum impact test; ---Added the corresponding description of the force calibration device (see 6.2.3); ---The normative appendix C "Small sample instrumented Charpy V-notch pendulum impact test" has been added. This standard uses the redrafting method to amend and adopt ISO 14556.2015 "Charpy V-notch pendulum impact test instrument for metal materials" Chemical test methods. The technical differences between this standard and ISO 14556.2015 and the reasons are as follows. --- Regarding normative reference documents, this standard has made adjustments with technical differences to adapt to my country's technical conditions and adjustments. The situation is collectively reflected in Chapter 2 "Normative Reference Documents", and the specific adjustments are as follows. ● Replace ISO 148-1 with GB/T 229 modified to adopt international standards (see Chapter 5, Chapter 7, Chapter 8); ● Replace ISO 148-2 (see 6.1) with GB/T 3808 modified to adopt international standards. ---Expanded the scope of application according to my country's situation "U-shaped notch samples can also refer to this standard"; ---According to the order in which the appendices appear in the text, the order of Appendix C and Appendix D has been adjusted. This standard was proposed by the China Iron and Steel Association. This standard is under the jurisdiction of the National Steel Standardization Technical Committee (SAC/TC183). Drafting organizations of this standard. Central Iron and Steel Research Institute, Baosteel Co., Ltd., Metallurgical Industry Information Standards Institute, Shenzhen Wance Test Equipment Co., Ltd., Steel Research Nac Testing Technology Co., Ltd., Xiwang Special Steel Co., Ltd. The main drafters of this standard. Gao Yifei, Chen Wu, Fang Jian, Dong Li, Huang Xing, Wang Tao, Liu Fei. The previous versions of the standards replaced by this standard are as follows. ---GB/T 19748-2005. Charpy V-notch pendulum impact test for metallic materials Instrumented test method1 ScopeThis standard specifies the terms and definitions, principles, specimens, test methods of the instrumental test method for the Charpy V-notch pendulum impact test of metallic materials. Test equipment and instruments, test procedures, test results evaluation and processing, and test reports. This standard applies to the measurement of the impact performance of the instrumental Charpy V-notch pendulum of metallic materials. Compared with the GB/T 229 Charpy pendulum impact test method, this standard provides more product-related faults than ordinary impact tests. Rift information. U-shaped notch samples can also refer to this standard. For general information about instrumented impact testing, see literature [3-8].2 Normative referencesThe following documents are indispensable for the application of this document. For dated reference documents, only the dated version applies to this article Pieces. For undated references, the latest version (including all amendments) applies to this document. GB/T 229 Charpy pendulum impact test method for metallic materials (GB/T 229-2007, ISO 148-1.2006, MOD) Inspection of GB/T 3808 Pendulum Impact Testing Machine (GB/T 3808-2018, ISO 148-2.2008, MOD)3 Terms and definitionsThe following terms and definitions apply to this document. 3.1 Eigenvalues of force 3.1.1 Yield force Fgy The force at the transition point of the force-displacement curve from the straight upward part to the upward part of the curve. Note. The yield force is the first-order approximation of the force when the entire ligament of the specimen yields (see 9.3). 3.1.2 Maximum force Fm The maximum force on the force-displacement curve. 3.1.3 Unstable crack growth starting force The force at the beginning of a sharp drop in the force-displacement curve (the beginning of unstable crack growth). 3.1.4 Unstable crack growth termination force Fa The force at the end of the force-displacement curve drop sharply.5 Test principle5.1 This test measures the relationship between the impact force and the bending displacement of the sample during the impact test in accordance with GB/T 229. Shift the area under the curve to measure the absorbed energy of the sample. 5.2 Even if the area (absorbed energy) under the force-displacement curve is the same, the force-displacement curve measured under different materials and different temperatures may be quite different. Big. If the force-displacement curve is divided into different characteristic parts, the different stages of the test process can be inferred, and the impact load speed A large amount of information on the deformation and fracture characteristics of the specimen. Note. The force-displacement curve cannot be used for structural strength calculations. It is impossible to directly determine the allowable minimum use temperature of structural materials.6 Test equipment and instruments6.1 Testing machine The impact testing machine should meet the requirements of GB/T 3808, and can automatically measure the force-time or force-displacement curve. The measured total impact energy Wt can be compared with the total absorbed energy KV indicated by the pointer or encoder of the testing machine. Note. The result of the instrumented method measurement is similar to the result indicated by the dial or encoder, but the value is different [8]. If the deviation between KV and Wt exceeds ±5J, the following checks should be done. a) The friction of the testing machine; b) Calibration of the measuring system; c) Application software. 6.2 Instruments and calibration 6.2.1 Traceability of measurement The calibration measurement of the instruments used should be traceable to national or international standards. 6.2.2 Force measurement The force measurement is usually obtained by sticking two resistance strain gauges to the impact blade to form a force sensor. For suitable design see Appendix A. Two strain gauges with the same force are attached to the opposite side of the impact blade, and a full bridge is formed with two compensating strain gauges or alternative resistors Circuit to obtain. The compensating strain gauge should not be attached to any part of the testing machine subject to impact or vibration. Note 1.Other force sensors that can meet the measurement requirements can also be used. The force measurement system composed of force sensors, amplifiers and recorders should have at least 100kHz frequency response, which is equivalent to signal rise The time tr is not more than 3.5μs. The dynamic response to the impact force measurement system can be simplified by measuring the load value corresponding to the first peak on the force-time or force-displacement curve Make an assessment. Experience has shown that for V-notch specimens, the distance between the contact point of the specimen and the center of the strain gauge on the impact blade is 11mm~ 15mm (see Appendix A), and the impact velocity is 5m/s~5.5m/s, if the first peak load is greater than 8kN, the measurement system is considered The dynamic response of the system meets the requirements of instrumented impact test. The instrumented characteristics of the pendulum should fully meet the required nominal measuring force range. Ensure the required force range. The design application of instrumented pendulum Reduce the sensitivity of asymmetric loading. Note 2.Experience has proved that the nominal impact force of samples with V-notch on most steels can reach 40kN. 6.2.3 Force calibration The static calibration of the recorder and measurement system should meet the following and the accuracy requirements of 6.2.4. It is recommended to calibrate the overall force value of the blade mounted on the hammer head. Connect a pair of calibrated force sensors to the blade The special force application frame is equipped with a special support block at the sample position to form a calibration tool, and the load is applied to the blade through the tool to perform instrumental force Value calibration. The support block should have high rigidity. The contact conditions between the tooling and the blade should be similar to the striking conditions between the blade and the sample during the test. Same, and can give reproducible calibration results. Note. Appendix B gives an example of a 2mm radius impact knife calibration support block. The instrumented pendulum and the static linearity and inherent hysteresis deviation of all measuring system and recording system components are. the force range is 10%~ When it is between 50%, it is ±1% of the full scale; when the force range is between 50% and 100%, it is ±2% of the indicating force (see Figure 1). When the force sensor is calibrated separately, it is ±1% of the indicated value between 10% and 100% of the nominal range. 6.2.4 Displacement measurement system The specimen displacement is usually determined by calculation of the force-time curve (see Chapter 9). Optical, inductive or capacitive non-contact methods can also be used to measure the displacement of the pendulum relative to the anvil. Displacement measurement system conversion The characteristic signal should be consistent with the force measurement system, so that the two recording systems are synchronized. The upper limit of the displacement measurement system is 30mm, and the linear error within the range of 1mm~30mm is ±2% of the measured value. The pendulum can be released to perform dynamic calibration of the displacement system without placing the sample, and the impact speed is determined by equation (1). The speed signal recorded when the pendulum passes the lowest position corresponds to v0. It is recommended that the displacement between 0mm and 1mm is obtained by the measurement time and the impact rate of the pendulum through double digital integration, see 9.1. 6.2.5 Recording device The recording of dynamic signals should be done with digital memory, and the test results can be output to an XY plotter or printer. In order to meet the requirements of 6.2.3 and 6.2.4 for the accuracy of the digital measurement and recording system, at least one 8-bit analog-to-digital converter is required. The sampling frequency should be 250kHz (4μs) or more. It is recommended to use a 12-bit analog-digital converter with a sampling frequency of 1MHz. For each in For a signal duration of 8ms or more, a memory with at least.2000 data points is required, and 8000 data points are recommended. If the signal continues The time is less than 8ms, and the storage capacity can be reduced proportionally. When it is necessary to determine the characteristic value from the force-displacement diagram, a graphic area of 100mm wide and 100mm high can ensure sufficient accuracy. 6.2.6 Calibration cycle The instrumented calibration cycle generally does not exceed 12 months, or the pendulum impact tester, the instrumented part is installed, moved, repaired or adjusted. Calibration should be added after the adjustment. If the pendulum is replaced, calibration is recommended, unless it can be proven that calibration is unnecessary.7 SampleCharpy notch impact specimens should meet the requirements of GB/T 229 or Appendix C.8 Test procedureThe test is carried out in accordance with GB/T 229, and the force-displacement curve is determined and evaluated according to different deformation and fracture characteristics.9 Evaluation and processing of test results9.1 General If the displacement is not measured directly, calculate the force-displacement curve as follows. The pendulum force-time relationship and acceleration characteristics to be measured Sex is proportional. If the effective mass of a pendulum with known stiffness is m, the initial impact rate v0, and the time t0 when the deformation begins, then the sample The bending displacement of is calculated by the integral calculation of formula (2) and formula (3). 9.2 Evaluation of force-displacement curve In order to simplify the assessment and reporting, Figure 2 shows the force-displacement curves of various types of features. The above curves can be divided into the following categories. ---Type A and Type B (under platform); ---Type C, Type D and Type E (transition type); ---Type F (upper platform). Only unstable crack propagation occurs in the type A force-displacement curve. For force-displacement curves of types B, C, D, and E, different quantities of Stable crack growth occurs. For class F curves, only stable crack propagation occurs. The type of force-displacement curve is determined by comparing with the various curve characteristics in Fig. 2 (column 2). For the force-displacement curve of type A, only Rate Fiu. For the B curve, only Fiu and Fa are evaluated. The oscillation superimposed on the force-displacement signal should be considered. The oscillation is caused by the interaction of force between the instrumented hammer blade and the specimen of. As shown in Figure 3, reliable eigenvalues are obtained through the oscillating fitting curve. 9.3 Determination of force characteristic value The yield force Fgy is the intersection of the second peak sharply rising part and the fitted curve without considering the initial inertia peak on the force-displacement curve Corresponding force (see the force-displacement curve of Type C~F in Figure 2). The maximum force is the force corresponding to the maximum value on the fitted curve passing through the oscillation curve. The initial force of unstable crack growth is the intersection of the fitted curve and the force-displacement curve at the beginning of the sharp drop after the maximum force. The force of the response. If this point coincides with the maximum force, then Fiu=Fm (see the C and D force-displacement curves in Figure 2). The unstable crack growth termination force corresponds to the intersection of the force-displacement curve and the subsequent force-displacement fitting curve when the force-displacement curve drops sharply. Force (see the D and E force-displacement curves in Figure 2). 9.4 Determination of displacement eigenvalues Determine the displacement characteristic value according to the abscissa corresponding to the force characteristic value determined in 9.3, see Figure 2. Note 1.The yield displacement Sgy is only roughly measured when the same measuring device is used. Therefore, Sgy is usually not used. Note 2.Due to the steep drop in the force-displacement curve between Fiu and Fa, it is usually considered Siu≈Sa. The total displacement St is only measured when the sample is completely broken and can be obtained. In this case, through the force-displacement curve of the oscillation The fitting approach force F=0.The total displacement St is the intersection point of the abscissa and the oscillation force F=0. Note 3.If the force does not return to zero within the selected test time, but the force value is close to the level F >0, use the abscissa corresponding to F=0.02Fm as the end point Calculate the total displacement. 9.5 Determination of the characteristic value of impact energy The energy W m under the maximum force passes through the area under the integral force-displacement curve from S=0 to S=Sm. The measurement of the initial energy of unstable crack growth Wiu is the area under the integral force-displacement curve from S=0 to S=Siu. Unstable crack growth termination energy W m measurement The area under the integral force-displacement curve from S=0 to S=Sa. Note. Since the force-displacement curve drops sharply between Fiu and Fa, it is usually assumed that Wiu=Wm. The total impact energy Wt is measured from the area under the integral force-displacement curve from S=0 to S=St. 10 Test report The test report should generally include the following. a) The standard number; b) Sample size; c) Sample identification; d) Sampling location and direction; e) Impact blade radius; f) Impact testing machine model and energy; g) Test temperature, ℃; h) Effectively absorb energy, KV2 or KV8, J. If the sample does not break and passes between the anvils, the test result should be included Number, and should indicate "not completely broken"; i) The characteristic values of force, displacement and energy, corresponding curves and the ductile section rate of the fracture surface can be given according to user needs; j) Measured characteristic values of force, displacement and impact energy; k) If required, the estimated value of the percentage of toughness fracture can be obtained by the formula in Appendix D.Appendix C(Normative appendix) Instrumented Charpy V-notch Pendulum Impact Test on Small Samples C.1 General Appendix C defines the requirements for instrumented Charpy V-notch pendulum impact test specimens and related measuring and recording equipment. This standard can also be used for other types of metal materials and other types of impacts such as drop hammers and high-speed hydraulic servos under mutual agreement. Testing Machine. This test provides further information on the fracture behavior of the specimen under the impact loading rate. The user should be aware that the data obtained from the small sample cannot be used for comparison with the data of the full-size Charpy V-notch impact sample. C.2 Test device C.2.1 Test machine The testing machine is similar to the impact testing machine for conventional V-notch specimens, and appropriate adjustments (such as impact rate, distance between anvils, etc.) need to be considered. Distance, the position of the sample relative to the hammer blade), see Figure C.1. Only when the available impact energy of the testing machine is not greater than 50J, the instrumented mass passes the total impact energy Wt and the testing machine dial The impact absorption energy KV shown by the pointer is compared to evaluate. ......Tips & Frequently Asked Questions:Question 1: How long will the true-PDF of GB/T 19748-2019_English be delivered?Answer: Upon your order, we will start to translate GB/T 19748-2019_English as soon as possible, and keep you informed of the progress. The lead time is typically 2 ~ 4 working days. The lengthier the document the longer the lead time.Question 2: Can I share the purchased PDF of GB/T 19748-2019_English with my colleagues?Answer: Yes. The purchased PDF of GB/T 19748-2019_English will be deemed to be sold to your employer/organization who actually pays for it, including your colleagues and your employer's intranet.Question 3: Does the price include tax/VAT?Answer: Yes. 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