31 Oct 2006
Testing steel by the Danube
Mittal steel, now the world’s number one steel company following its merger with Arcelor, recently took delivery of an Imatek DWT40-25 test system. The new machine is located in Mittal’s steelworks in city of Galati in Romania, on the banks of the river Danube, about 150km from where it empties into the Black Sea.
The DWT40-25 is designed to perform the DWTT, or Drop Weight Tear Test, in accordance with all international standards. Equipped with the variable mass option, Mittal’s machine has a maximum test capacity of 24,500J.
In its simplest form, the drop weight tear test consists of breaking a notched specimen of steel into two pieces by subjecting it to a three-point bend. Typically this is done at low temperature, and the broken faces of the specimen are examined to estimate the proportion of brittle and ductile failure. The test is an important quality control procedure for pipeline steel, since the failure of a high-pressure pipeline can have devastating economic and environmental consequences.
Imatek’s DWT40 systems have a pneumatic sample loader which places the specimen quickly and precisely on the anvil prior to impact. This ensures compliance both with the requirements of the test geometry, and also the stipulation in the standards that the test piece must be broken within ten seconds of removal from the cooling bath. It also has the not insignificant safety benefit of keeping the operator well away from the test area, and a ton of steel waiting to fall.
In order to obtain maximum data from each test, all of Imatek’s DWTT systems are instrumented with a load cell behind the impact ‘hammer’. This provides a high resolution record of the forces encountered during the impact, which can be used to derive a number of useful results, such as yield force, ultimate tensile strength and energy to fail.
Comprehensive data such as this gives Mittal, and its customers, confidence in the quality of its steel products.
