What is the DWTT test?
The Drop Weight Tear Test (DWTT) was developed at the Battelle Institute in the early 1960s. That is why the DWTT test is also colloquially called the Battelle Test. Sometimes it is even referred to as the BDWTT test. The aim of this mechanical material test is to prevent brittle fracture and to ensure crack arrest in pipelines (seamless or welded).
How is the DWTT test carried out?
The DWTT drop-weight test is a mechanical-technological toughness test on steels in which a defined weight is dropped vertically from a defined height onto a sample to break it. In contrast to the notched bar impact test, these are so-called large drop tests (from 20,000J) which are usually very high (approx. 3-12 metres). The specimen, mounted as in a three-point bending machine, has a cold-pressed notch, whereby the impact is opposite the notch. The energy – weight and notch height – is set to break the specimen and the fracture surface can be visually assessed. The result of the Battelle DWTT drop weight test is the appearance of the fracture surfaces. The proportions of the deformation fracture surface (ductile) and brittle fracture surface (crystalline) are determined visually. Furthermore, as with the notched bar impact test, the impact energy consumed at a certain temperature can be evaluated.
For which steel grades is the DWTT test used?
The test is not a typical mechanical material test on sheet metal, but is mainly used for pipes. Here the steels for line pipes according to API5L e.g. X60, X65, X70 or according to EN DIN EN ISO 3183 L415 (1.8725 or 1.8766), L450 (1.8726 or 1.8767) and L485 (1.8727 or 1.8768) should be mentioned or for steels from the M-630 Material data sheet and element data sheets for piping.
What are the application areas of DWTT tested steels?
The steels for line pipes are used in transport systems for liquid crude oil and natural gas and their accessories. Another application for this steel is in the petrochemical industry.