The fracture test (also called a break test) is a destructive weld test in which specimens taken from welded joints are broken through the weld metal and the fracture surfaces are examined. It gives direct information on the type, size and distribution of internal imperfections. FKT NDT provides fracture testing, particularly for fillet welds and butt welds.
What Does the Fracture Test Show?
A weld can look sound from the outside and still contain imperfections at the root or inside the weld metal. The fracture test opens the weld and makes them visible. The main imperfections assessed on the fracture surface are:
- Pores
- Cracks
- Lack of fusion
- Lack of penetration
- Solid inclusions (slag etc.)
On fillet welds, the test also helps to assess root penetration and weld size (throat thickness).
Where Is It Used?
- Welder qualification: widely used in fillet weld tests, and in some cases on butt welds.
- Verifying a welding procedure: checking internal weld quality after a new procedure or a parameter change.
- Production control: monitoring weld quality on sample parts in series production.
The fracture test is usually assessed together with visual inspection and macro examination. For the variant in which butt welds are notched before breaking, see our nick-break test page.
Standards
The fracture test is commonly applied according to:
- ISO 9017: Destructive tests on welds in metallic materials – Fracture test
- ISO 9606-1: Qualification testing of welders – Fusion welding – Steels (test pieces and acceptance criteria)
- ISO 5817: Quality levels for imperfections in fusion-welded joints in steel (referenced in acceptance criteria)
How the Test Is Performed
- Specimen preparation: the fillet-welded test piece is cut into one or more pieces as specified in the standard. Butt-weld specimens are notched where needed so that fracture occurs in the weld metal.
- Breaking: on a fillet weld specimen, the upright plate is loaded so as to open the weld root and bent until the weld fractures. Load is applied by press, hammer or a suitable fixture.
- Examination: the fracture faces are examined visually and, where needed, with a magnifier. The type, size and position of imperfections are recorded.
- Evaluation: findings are compared with the acceptance criteria of the applicable standard.
- Reporting: the report gives specimen identification, weld type, imperfections found and the result. Photographs of the fracture faces can be added on request.
FAQ
How is a fillet weld fracture test done?
On a T-joint specimen, force is applied to the upright plate in the direction that opens the weld root and increased until the weld breaks. The fracture surface is then examined for root penetration and internal imperfections.
What is the difference between the fracture test and the nick-break test?
Both break the weld open to inspect internal imperfections. In the nick-break test the specimen is notched first, and it is mostly used on butt welds. The fracture test can also be done on un-notched specimens, especially fillet welds.
Can the fracture test replace non-destructive testing?
No. The fracture test only represents the area where the specimen was taken and destroys it. Non-destructive testing methods are used to check production welds in full.
How are acceptance criteria set?
By the applicable qualification standard. ISO 9606-1 refers to the quality levels of ISO 5817 for assessing fracture tests.
To arrange a weld fracture test, contact us with the weld type and applicable standard, and we will prepare a quotation.