Difference between Izod impact test and Charpy impact test?

Answer 1

1) The test notches for the impact specimens for the tests have different dimensions. The Izod test is a V-notch; the Charpy test has three different specimen types: Key-hole, U-notch, and V-notch. However, other specimen types may be specified as required for both tests.

2) The specimens are held differently. The Izod specimen is held in a cantilevered manner; the Charpy test is held such that the specimen rests against two supports on either side of the test notch.

3) The impact location is different. The Izod test impact is against the end of the exposed cantilever; the Charpy test is struck directly behind the test notch such that the specimen undergoes three point bending.

4) The test specimens have different dimensions. The basic Izod test specimen is 75 x 10 x 10mm (2.95" x 0.394" x 0.394"); the basic Charpy test specimen is 55 x 10 x 10mm (2.165" x 0.394" x 0.394")

It's really a stretch to give 4 points of difference, particularly as these tests may be altered as required depending on the material performance characteristic being investigated.

Source(s):Degarmo, E. Black, J. Kohser, R. 2003, Materials and Processes in Manufacturing: Ninth Edition. John Wiley and Sons Inc. pp. 40 - 41