Charpy

Charlie CHARMm Charpy Izod impact Charpy method Charpy test CHARTEK59 Charybdotoxin Chaser mill Chatecholates... 

The cast zinc—aluminum—copper slush alloy, after aging for ten years indoors, shows a tensile strength of 238 MPa (34,500 psi) with Charpy impact strengths of 1.4—4.1 J (1—3 ft4bf) (87). 

Samples S/B mole. b ratios Elongation at break, % Light transmittance, % Charpy impact strength, J /m Heat distortion temperature, °C... 

Materials selection for low-temperature service is a specialized area. In general, it is necessaiy to select materials and fabrication methods which will provide adequate toughness at all operating conditions. It is frequently necessaiy to specify Charpy V-notch (or other appropriate) qu fication tests to demonstrate adequate toughness of carbon and low-aUoy steels at minimum operating temperatures. 

Impact tests are, however, used to try to compare the impact strength of different materials. Of these tests four require specific mention. These are the Izod test, the Charpy test, the falling weight tests and the tensile impact test. 

Figure 9.5. Graph showing that there is an approximate correlation between Izod and Charpy impact...

An alternative to the Izod test is the Charpy test in which a sample supported, but not gripped, at each end is subject to an impact in the centre. According to the test a notch may be present in the centre of the sample on the face opposite to that subjected to impact. In spite of the differences between the tests there is a surprisingly good correlation between Izod and Charpy test results as shown by Figure 9.5 based on tests on several thermoplastics. ... 

Charpy notched impact strengths in excess of 55 kJ/m have been reported for alloys with homopolymers and in excess of 20kJ/m for copolymers. 

Figure 10.6. (a) Indentation nanohardness of silver/chromium multilayers and single films of the constituent metals, as a function of depth affected by plastic deformation, (b) Charpy impact energies, a measure of fracture toughness, of three materials, as a function of test temperature they are mild steel, ultrahigh-carbon steel and a composite of the two kinds of steel (courtesy Dr. J. Wadsworth) (Fig. 10.6(b) is from Kum et at. (1983)). 

Although the Izod and Charpy tests are widely used for plastics, other types of test are also popular. These include tensile impact tests and flexural plate (falling weight) tests. The latter is particularly useful in situations where the effects of flow anisotropy are being assessed. In addition, arbitrary end-product tests are widely used to provide reassurance that unforseen factors have not emerged to reduce the impact performance of the product. 

Fig. 2.82 Comparison of impact strengths as measured by Charpy test...

In recent years impact testing of plastics has been rationalised to a certain extent by the use of fracture mechanics. The most successful results have been achieved by assuming that LEFM assumptions (bulk linear elastic behaviour and presence of sharp notch) apply during the Izod and Charpy testing of a plastic. 

Example 2.23 A series of Charpy impact tests on uPVC specimens with a range of crack depths gave the following results... 

Tensile and flexural properties were studied with an Instron 4204 testing machine. Tensile tests were performed on the drawn strands at a test speed of 3 mm/ min, while three-point-bending tests (ISO 178) at a speed of 5 mm/min were applied to the injection molded specimens. Charpy impact strength was measured of the unnotched samples with a Zwick 5102 pendulum-type testing machine using a span of 70 mm. The specimens (4 X 10 X 112 mm) used for three-point-bending tests were also used for the impact tests. It should be noted that neither the tensile tests for the strands nor the impact tests were standard tests. The samples were conditioned for 88 h at 23°C (50% r.h,) before testing. 

Table 6 Effect of Cure Inhibitor Concentration on the Charpy Notched Impact Strength (ak) at O C...

It was found that PP-EPDM blends [30] with a slow curing EPDM have a high-impact strength. Effect of tet-ramethyl thiuram disfulfide (TMTD) concentration on the Charpy notched impact strength of PP-EPDM blend is given in Table 8. 

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