During the 19th century, the railroad had an important and rapid development in both Europe and the United States.

All this involved the construction of locomotives, tunnels, bridges, stations and many other structures.

Parallel to this development, unexpected ruptures began to appear between 1840 and 1860: most of them occurred without warning because they were due to brittle fractures.

These ruptures began to be investigated, and it was found that they could occur even when stresses were less than critical. All of this occurred in the presence of random or periodic cyclic loads. Thus the phenomenon of fatigue was discovered.

Therefore, the need arose to find a test that could predict the behavior of metallic materials when subjected to cyclic stress. It took several years and several stages to arrive at defining an evidence that everyone agreed on. Let’s look at some of them.

In 1857 Captain T.J. Rodman devised the first drop-weight machine to improve the performance of steels intended for weapons.

In 1892 Le Chatelier introduced the use of carved specimens for testing to be performed with the drop-weight machine. He found that the presence of notching caused brittle fracture on steels that showed ductile fracture when not notched.

S. Bent Russel in 1898 devised a new machine in which he used a hammer-shaped pendulum. The purpose of this machine was to measure the energy absorbed by the test specimen by calculating the difference between the pendulum height before and after fracture. This pendulum had a considerable size and was capable of fracturing full-section specimens.

At the same time, 1901, in France, George A. A. Charpy, used a pendulum very similar to the one used today, where he employed carved bars, however. Its purpose was to standardize the test so that a database with uniform data could be created.

From this time on, metallurgists focused on finding a standardization of the test. Two auditions were mainly employed:

10 x 10 mm cross-section with a length of 53 mm and a notch 2 to 5 mm deep with a radius of 1 mm.

A specimen with the same proportions as the previous one but with the dimensions multiplied by three.

The smaller audition turned out to be the winner because it allowed the use of smaller and cheaper machines.

Tests performed with standardized specimens quickly brought the first important results. During the IATM congress (1912) a steel manufacturer presented a report showing that due to the improvement given by resilience testing he had managed to reduce by twenty times the number of parts discarded due to brittle behavior.

In 1922 ASTM organized a symposium devoted to resilience testing, and the following year an ASTM subcommittee was appointed with the purpose of preparing a standard for resilience testing.

A good 10 years before ASTM E23-33T “Tentative Method of Impact Testing of Metallic Materials” was published, where it defined the use of the pendulum, both Charpy and Izod, the V-notched specimen and the English unit system.

This standard still exists and has reached the 2018 revision.

Arguments arose regarding the radius that the mace knife should have, which in the UK was 0.57 mm while in France it was 2 mm.