Flow modelling of friction stir welding using brass markers in copper
(English)In: Science and technology of welding and joining, ISSN 1362-1718Article in journal (Other academic) Submitted
This paper describes the behaviour of the material flow in 50 mm thick friction stir welded phosphorous-alloyed copper with both experiments and modelling work. In Sweden the friction stir welding is going to be used for sealing copper canisters for storage of nuclear waste from fuel elements. An understanding of the material flow during the process is essential in order to predict the weld quality and thereby the maintenance of the weld. A marker technique is used which involves inserting dissimilar material into the weld zone before joining. The material flow can then be examined. In these experiments Ø 9 brass rods are used. After welding, the copper was sliced, etched and examined by optical microscopy. The results show that the weld tool pushes the brass as far as 37 mm backwards from the inserted location, which is little more than one pin diameter. This brass is first seen on the advancing side. Most brass is found behind its inserted location, on both sides of the centre line. The material movement underneath the pin in the weld root is insignificant. The pin area has a nugget with a fine grain structure, but also a part near the shoulder with coarser grains. A finite element model is developed in order to describe the temperature and material flow. The model and the examined welds were compared showing a satisfactory agreement for most features.
friction stir welding, viscous flow, marker, finite element method
IdentifiersURN: urn:nbn:se:kth:diva-12016OAI: oai:DiVA.org:kth-12016DiVA: diva2:294199
QS 201203282010-02-162010-02-162012-03-28Bibliographically approved