Charpy Impact Tests

The Charpy Impact Test is commonly used on metals, but is also applied to composites, ceramics and polymers. It is most commonly used to evaluate the relative toughness of a material, and as such, it is used as a quick and economical quality control device. The standard Charpy Impact Test specimen consist of a bar of metal, or other material, 55x10x10mm having a notch machined across one of the larger dimensions.

• V-notch: 2mm deep, with 45° angle and 0.25mm radius along the base
• U-notch and keyhole notch: 5mm deep notch with 1mm radius at base of notch

Charpy impact tests assess the performance of metallic materials under sudden loading. A swinging pendulum of known potential energy is used to strike the specimen and the energy absorbed by the specimen is recorded. The manner in which the specimen fails will indicate its toughness and the absorbed energy value is used as a comparison against specific compliance criteria of an applicable standard. The material standard or the welding code specifies the type, location and orientation of the notch.

Lateral expansion is a measure of the ability of a specimen to resist fracture when subjected to triaxial stresses. The amount of lateral expansion is directly proportional to the fracture toughness.

Shear percentage is a visual method used to determine the percentage of a fracture surface which is ductile or brittle. Both of these measurements are performed on fractured Charpy V-Notch impact specimens.

LMATS can perform the Charpy Impact Test to the following standards:

AS/NZS 1544.2; ASTM E23; ISO 148.1; AS/NZS 3992; ASME IX; ASME B31.3; AWS D1.1 and ASTM A370.