Since both tests measure energy absorption of notched specimens, of course their is a relationship.
According to the ASM Handbook Volume 8 Mechanical Testing and Evaluation:
"The Charpy V-notch test continues to be the most utilized and accepted impact test in use in the industry."
"The disadvantage that has caused it [Izod test] to lose popularity is that the required time for and method of clamping the specimen in an anvil preclude low-temperature testing."
Regards,
Cory
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
The Izod test cannot be performed at low temperatures.
Often, the same testing machine can be used for both type of specimens, but the striking tup must be swapped out. Interpetations of ASTM E-23 have been made that require the machine to re-certified for Charpy testing (a new set of standardized specimens) if the striking tup is replaced, so few labs will perform Izod testing these days.
Many years ago, I ran comparison tests on Charpy and Izod tests (at room temperature) on redundant samples of materials with different impact strengths. At lower impact strengths (below around 40 Ft-Lbs), the Izod result was comparable to the Charpy result. At higher impact levels, the Izod result would come in below the Charpy result.
