Characterization of the delamination behavior of tungsten based alloys by means of acoustic emission

To rank attempts of improving the resistance of thin (<0.5 mm) tungsten sheet-material against delaminations, there is a need for a testing procedure which allows to measure the tendency of the material to from delamination cracks. In this contribution, several testing procedures are examined with respect to their ability to initiate delaminations. The reverse bending test turned out to be the most suitable procedure to measure the delamination behavior.The observation of acoustic emission allows an accurate detection of the moment of crack formation and the corresponding bending angle. To get information about the stress distribution during a test, a finite element analysis was carried out. It is shown that specific parameters of the hot rolling process influence the delamination behavior of the sheet material in a significant and reproducible manner. Other fracture patterns like 45° embrittlement were also observed and were correlated to specific hot rolling conditions.