1、GM DAEWOO Auto & Technology EDS Engineering, GM DAEWOO Auto & Technology Standards TEST METHOD OF IMPACT FOR METALLIC MATERIALS EDS-T-7115 ISSUED DATE: 1990. 12. 29 REVISED DATE: 2006. 06. 19 VERSION: 3 EDS-T-7115TEST METHOD OF IMPACT FOR METALLIC MATERIALS PAGE: 1/6 ISSUED DATE: 1990. 12. 29 REVISE
2、D DATE: 2006. 06. 19 VERSION: 3 GM DAEWOO Auto & Technology 1. PURPOSE This standard specifies the CHARPY impact test for metallic materials (hereinafter referred to as the “impact test“) so that it aims at performing a correct test. 2. SCOPE This standard specifies the impact test. However, it does
3、 not apply to the metal with low impact value such as the cast iron, the alloy for die castings. 3. DEFINITION 3.1. Impact test: A test, to be made on a CHARPY impact testing machine for the determination of the of the absorbed energy, impact value, percent fracture and transition temperature specif
4、ied in 3.2, 3.3 and 3.4 to 3.11, in which a test piece, which is supported on two supports of 40mm distance from each other and so located that its notch meets the middle between the supports is broken in the middle of the face opposite to the notch by one blow of the hammer. 3.2. Absorbed energy: T
5、he energy (kgf.m) J required for breaking the test piece on the impact testing machine. 3.3. Impact value: The quotient (kgf.m/cm2)J/cm2 of absorbed energy (kgf.m) J divided by the original cross-sectional area of the notched part(cm2). 3.4. Percent brittle fracture: The percentage of the area of br
6、ittle fracture to the total area of fracture of a test piece. The brittle fracture surface is that in which many crystal grains show cleavage or intercrystalline fracture and looks shiny (Fig. 1). 3.5. Percent ductile fracture: The percentage of the area of ductile fracture to the total area of frac
7、ture of a test piece. The ductile fracture surface is that which shows fibrous shear fracture and looks dull (Fig. 2). 3.6. Transition temperature: When test pieces are subjected to the tests at varied temperatures, the detected temperature at which the material exhibits a significant change in beha
8、vior such as the steep fall(or rise) in absorbed energy or the change in appearance of fracture surface from ductile to brittle(or from brittle to ductile). 3.7. Transition curve: The curves showing the relations between the testing temperature and the behavior such as absorbed energy, or fracture a
9、ppearance at the transition temperature and its vicinity (Fig. 3). 3.8. Fracture surface transition temperature: The transition temperature corresponding to the change in appearance of fracture surface, i.e. the temperature at which specific percent brittle fracture or percent ductile fracture is ob
10、served (Fig. 3). Remark: In the impact test using No. 2 test piece, the temperature at which percent ductile fracture becomes 50% is generally specified. EDS-T-7115TEST METHOD OF IMPACT FOR METALLIC MATERIALS PAGE: 2/6 ISSUED DATE: 1990. 12. 29 REVISED DATE: 2006. 06. 19 VERSION: 3 GM DAEWOO Auto &
11、Technology 3.9. Energy transition temperature: The temperature which corresponds to the average obtained from the absorbed energy corresponding to the lowest temperature at which the percent ductile fracture is 100% and the absorbed energy corresponding to the highest temperature at which the percen
12、t brittle fracture is 100%(Fig. 3). 3.10. Lateral expansion: Increase in the width of fracture surface of the test piece on the impact side (the opposite side to notch) over the original one (Fig. 2). 3.11. Lateral expansion transition temperature: The transition temperature which corresponds to the
13、 change in lateral expansion, i.e. the temperature at which the lateral expansion becomes a specific value. Remark: The lateral expansion transition temperature is generally obtained by impact test for No. 2 test piece. 4. TEST PIECE 4.1. No. 1 test piece 4.2. No. 2 test piece 4.3. No. 3 test piece
14、5. TESTING MACHINE EDS-T-7115TEST METHOD OF IMPACT FOR METALLIC MATERIALS PAGE: 3/6 ISSUED DATE: 1990. 12. 29 REVISED DATE: 2006. 06. 19 VERSION: 3 GM DAEWOO Auto & Technology 5.1. The impact testing machine used for impact testing shall conform to the using principles (KS D 5522, 5523) of impact te
15、sting machine. 5.2. The testing machine shall be used as installed on a rigid foundation with the axis of rotation of the hammer positioning horizontal. 5.3. A testing machine of which main parts have been overhauled and reassembled or modified, or which has been reinstalled shall, before use, be ve
16、rified for accuracy in accordance with the requirements of the foregoing standards. 5.4. The reverification of accuracy shall be carried out at certain intervals varying depending on the frequency of use, excepting the case prescribed in 5.1.3. 5.5. Before and after a series of tests, the testing ma
17、chine shall desirably be checked for the energy loss caused by friction and air resistance of the hammer and by friction of the pointer. 6. TEST METHOD 6.1. The test piece shall be set accurately in position, so that its notch meet the centre between the supports, and the deviation of the plane of s
18、ymmetry of the notch from the centre between the supports shall be as little as practicable and not more than 0.4mm. 6.2. The test shall be performed at the specified temperature. 6.3. For the test at the room temperature, unless otherwise specified, the test temperature shall be within the limit of
19、 10 to 30 in general, and the test temperature shall be recorded. However, for a material whose test results may be affected by the test temperature, it shall, as a rule, be 20 2, and conform to indications of the specification for the material. 6.4. For the test at low temperature, the test piece s
20、hall be kept at a constant temperature which is held in a liquid bath maintained at the specified test temperature within 2 for at least 10 minutes, or in a gas chamber maintained at the same temperature for at least 20 minutes, afterwards taken out and placed on the supports of the testing machine,
21、 and then struck with the hammer. In the above, the test piece in the liquid bath or gas chamber shall be held so that its boundaries are completely dipped in the cooling liquid or gas, and the measurement of the temperature of the liquid bath or gas chamber shall be taken in the vicinity of the tes
22、t piece. The test piece shall be struck within 5 seconds after it has been taken out of the liquid bath or gas chamber. Remark: During the dipping of the test piece in the liquid bath, the test piece shall preferably be held on a grid distant from the bottom of bath and dipped 25mm or more beneath l
23、iquid surface. 6.5. For the test at high temperatures of 200 or less, the test piece shall be kept at a constant temperature for at least 10 minutes in a liquid bath maintained at the specified temperature within 2. For the test at high EDS-T-7115TEST METHOD OF IMPACT FOR METALLIC MATERIALS PAGE: 4/
24、6 ISSUED DATE: 1990. 12. 29 REVISED DATE: 2006. 06. 19 VERSION: 3 GM DAEWOO Auto & Technology temperatures over 200, it shall be kept at a constant temperature for at least 20 minutes in a gas chamber maintained at the specified temperature within 5. Afterwards, the test piece shall be set on the su
25、pports and struck by hammer. In this case, holding of test piece in the bath and chamber, measurement of temperature and the time lapse from taking out the test piece to striking shall be same as 6.4. Remark 1. For the test at low or high temperatures, it is recommended that the following media shal
26、l be used for cooling or heating the test piece. Test temperature 500 - 200 Gas(use heating furnace) 200 - room temperature High temperature oil(use oil bath) 0 Ice and water 0 - -70 Alcohol or acetone, and dry ice grain -70 - -155 Isopentane cooled with liquid nitrogen -196 Liquid nitrogen 2. For t
27、he testing at a temperature other than room temperature, it is recommended to use a jig for quickly locating the test piece in an accurate position, when placing it on the supports after taking it out of the liquid bath or gas chamber. That part of the jig which comes into contact with the test piec
28、e shall be at the same temperature as that of the test piece. 6.6. The number of test pieces used for the determination of impact test value shall be in accordance with the requirements of the specification for the material. Unless otherwise specified, three test pieces shall be used for one tempera
29、ture condition, as a rule. The number, however, may be two, if the test values show little deviation. 7. DETERMINATION OF IMPACT VALUE, PERCENT FRACTURE AND TRANSITION TEMPERATURE 7.1. The energy E(kgf m)J required for breaking the test piece shall be obtained by the following formula: E = WR (cos -
30、 cos) Where, W : weight of hammer (kgf) N R : distance from centre of axis of rotation to centre of gravity of hammer(m) : angle of fall of hammer : angle of rise of hammer in its swing after breaking test piece. 7.2. The value of the energy E required for breaking the test piece shall be rounded of
31、f to the first decimal place in accordance with KS A 0021. However, to obtain more precise value E requires to use the following formula: E = WR(cos - cos ) - L Where, W : weight of hammer (kgf) N R : distance from centre of axis of rotation to centre of gravity of hammer (m) : angle of fall of hamm
32、er : angle of rise of hammer in its swing after breaking test piece. L : loss of energy during the swing of hammer(kgfm) J EDS-T-7115TEST METHOD OF IMPACT FOR METALLIC MATERIALS PAGE: 5/6 ISSUED DATE: 1990. 12. 29 REVISED DATE: 2006. 06. 19 VERSION: 3 GM DAEWOO Auto & Technology 7.3. Percent brittle
33、 fracture B(%) shall be obtained on the basis of the observation of the fracture surface of the test piece(Fig.1) by the use of the following formula: 100(%) =ACBWhere, A : total area of fracture surface C : area of brittle fracture surface The value B of the percent brittle fracture shall, as a rul
34、e, be obtained to the 5% intervals at least. And the percent brittle fracture may be obtained by comparison with the standardized fracture surfaces whose percent brittle fractures have been already determined. In this case, it is recommended to use the standardized fracture surfaces having been prep
35、ared at about 10% intervals of percent brittle fracture. And if the fracture surface part of the test piece shows no remarkable deformation for the calculation of the percent fracture, the original cross-sectional area of the notched section of the test piece may be taken as the total area of fractu
36、re surface. Fig. 1. Fractured Part 7.4. The percent ductile fracture S(%)= F over A 100 shall be obtained in the same manner as that described in clause 7.3, where F means the area of ductile fracture. 7.5. For measuring the lateral expansion, the following procedure shall be taken: Let one impact s
37、ide adjoin another of the two broken halves (the opposite side to the notch, as shown in Fig. 2) so that the sides (the sides at right angles to the notch) of the ends of the test piece where no deformation is produced are in the same plane. Take the width between the sides of the ends(b in Fig. 2)
38、as the reference, measure the width between the most laterally expanded parts on the fracture surface (a in Fig. 2), and then take the difference in reference width as the lateral expansion. The value of lateral expansion shall, as a rule, be rounded off to the first decimal place in accordance with
39、 KS A 0021. Fig. 2. Breaking Surface EDS-T-7115TEST METHOD OF IMPACT FOR METALLIC MATERIALS PAGE: 6/6 ISSUED DATE: 1990. 12. 29 REVISED DATE: 2006. 06. 19 VERSION: 3 GM DAEWOO Auto & Technology Remark: When measuring the lateral expansion, it shall be noted that the lateral expansions on the fractur
40、e surface of the broken halves do not always meet each other(as example in Fig. 2, the lower broken half is more expanding to the left and the upper one to the right.) 7.6. Generally, for determination of transition curves, tests shall, as a rule, be carried out at several suitable test temperatures
41、 in the transition temperature region including the temperature corresponding to the 100% ductile fracture and that to the 100% brittle fracture. Transition curves shall be drawn by the use of the absorbed energy, percent ductile (or brittle) fracture or lateral expansion taken on the ordinate, and
42、the test temperature taken on the abscissa, and they shall pass through nearly the middle of the plotted points representing the test results (Fig. 3). Drawing of transition curves shall not use extrapolation. 7.7. The fracture transition temperature and the energy transition temperature shall be de
43、termined by the use of the transition curves drawn as described in 7.6 above in accordance with the definitions of 3.8 and 3.9 (refer to example shown in Fig. 3). However, the energy transition temperature may be obtained, as the temperature corresponding to the value equal to the absorbed energy at
44、 the temperature where the percent ductile fracture becomes 100% subject to the agreement between the parties concerned. And the range of test temperatures necessary to the transition curves for determination of transition temperatures is enough if the use of interpolation enables the required trans
45、ition temperatures to be obtained. Fig. 3. Transition Curve 8. REFERENCE KS B 0809 Test pieces for impact test for metallic materials KS B 0810 Method of impact test for metallic materials JIS Z 2202 Test Pieces for Impact Test for Metallic Materials JIS Z 2242 Method of Impact Test for Metallic Materials
