Charpy Impact Test

Charpy impact test is also known as the Charpy v-notch test, and it is a destructive mechanical test in which a pendulum hammer (swinging through a fixed distance) fractures a standardize notched piece of material with one blow. The material respond to sudden applied load (Impact) by measuring the energy absorbed in breaking the piece.

This absorbed energy is a measure of a given material's toughness and acts as a tool to study temperature-dependent brittle-ductile transition. It is widely applied in industry, since it is easy to prepare and conduct and results can be obtained quickly and inexpensive

NUSATEK provide charpy impact testing on various types of steel products from raw material, welded joint to a complete finish product. Our laboratory is equipped with a charpy machine with a capacity of up to 600 Joules and capable of conducting tests at various temperatures from -196oC to ambient temperature.


Test Method/Specifications

  • ASTM A370
  • ASTM E23
  • BS EN ISO 148-1
  • Read More


    Impact testing becomes essential in order to study the behavior of welded objects under dynamic loading. An impact test determines the behavior of welds when subjected to high rates of loading, usually in bending. An impact test gives an indication of the relative toughness of the material. Toughness is defined as the resistance of a metal to fracture after plastic deformation has begun. The purpose of impact testing is to determine the amount of impact a specimen will absorb before fracturing. 

    In an impact test, a specimen machined or surface ground and notched is struck and broken by a single blow in a specially designed testing machine. The quantity measured is the energy absorbed in breaking the specimen by a single blow. The ideal impact test would be one in which all the energy of a blow is transmitted to the test specimen.

    Charpy impact test specimens are cut from metal samples, and a V-notch is placed in the center. Charpy impact testing can be performed at ambient and low temperatures (down to -196°C).

    Low temperature charpy testing involves placing the specimens into a cooling chamber bath, and leaving specimens while a calibrated thermocouple records the temperature required for the test.  Charpy test specimens are then removed from the chamber, and immediately tested for joules/lbs force by a swinging arm pendulum (which records the value to propagate the cut V-notch).The energy transferred to the material can be inferred by comparing the difference in the height of the hammer before and after a big fracture.

    The notch in the sample affects the results of the impact test, thus it is necessary for the notch to be of regular dimensions and geometry. The size of the sample can also affect results, since the dimensions determine whether or not the material is in plane strain. This difference can greatly affect conclusions made.

    The "Standard methods for Notched Bar Impact Testing of Metallic Materials" can be found in ASTM A370, ASTM E23 and BS EN ISO 148-1, where all the aspects of the test and equipment used are described in detail.


    Specimen Size



    Table above shows charpy impact specimen size according to ASTM A370 and BS EN ISO 148-1. Standard size specimen for impact test is 55.0mm x 10.0mm x 10.0mm for both standards



    Quantitative Result

    The quantitative result of the impact tests the energy needed to fracture a material and can be used to measure the toughness of the material and the yield strength. Also, the strain rate may be studied and analyzed for its effect on fracture.

    The ductile-brittle transition temperature (DBTT) may be derived from the temperature where the energy needed to fracture the material drastically changes. However, in practice there is no sharp transition and so it is difficult to obtain a precise transition temperature. An exact DBTT may be empirically derived in many ways: a specific absorbed energy, change in aspect of fracture (such as 50% of the area is cleavage), etc.



    Qualitative Results

    The qualitative results of the impact test can be used to determine the ductility of a material. If the material breaks on a flat plane, the fracture was brittle, and if the material breaks with jagged edges or shear lips, then the fracture was ductile. Usually a material does not break in just one way or the other, and thus comparing the jagged to flat surface areas of the fracture will give an estimate of the percentage of ductile and brittle fracture. The figure below shows the surface of broke Charpy specimen.