Nick Break Test

Definition - What does Nick Break Test mean?

A nick break test is a type of destructive testing that is used to evaluate the quality of a weld. To perform a nick break test, a specimen is prepared out of the weld metal. Stress concentrators are then machined into the specimen. The specimen is then broken and the fracture surface is observed at the conclusion of the nick break test.

Corrosionpedia explains Nick Break Test

A nick break test is used primarily to evaluate weld samples. Two notches are produced on each side of the weld of the test sample. The notches are machined in the area that the fracture is desired. Then, a device (typically similar to the equipment used in Charpy V-Notch testing) is used to create an impact that fractures the weld. Following the fracturing process of the nick break test, the fracture surface is observed and the weld quality is evaluated.

Several different types of weld discontinuities and defects can be found using a nick break test:

  • One common discontinuity is porosity, which shows itself as a smooth dimple on the fracture surface.
  • Another common discontinuity is slag inclusions, which are a concern for processes that use flux. Slag inclusions reveal themselves during a nick break test as a non-metallic substance on the fracture surface.
  • Other discontinuities include lack of fusion and lack of penetration.
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