Entwicklung einer Prüfmethode zur Untersuchung des Schädigungsverlaufs von widerstandspunktgeschweißten Automobilstählen
Research output: Thesis › Master's Thesis
The weldability of third generation Advanced High Strength Steels is limited due to their relatively high alloy content and the rapid cooling during resistance spot welding. An in-process heat treatment via a second pulse can be carried out to improve the quality of a weld. In this master's thesis, the applicability of a new test method for investigating the damage behavior of high strength steel spot welds through interrupted tensile tests was examined. In addition, a suitable manufacturing and preparation method had to be found, and a reproducible test routine had to be established. Mounting in an acetone-dissolvable cold mounting resin, machine sample preparation, and electrolytic polishing gave the best results. Subsequent etching with cold-saturated picric acid creates a strong contrast between the weld nugget and the base material and was therefore particularly suitable for assessing the fracture character. While a single welding pulse leads to interfacial failure, a pullout failure can be achieved by a recrystallization pulse. The results of the master's thesis show that the macroscopic behaviour can be simulated, and the damaging process can be observed in detail. The test method developed in this master's thesis will be used in the future as part of a cooperation with the University of Sydney, Australia for in-situ tensile tests in the scanning electron microscope. Therefore, comprehensive knowledge can be gained in order to optimize the relationships between welding parameters, microstructure, and properties.
|Translated title of the contribution||Development of a test method to investigate the damage behavior of resistance spot welded automotive steels|
|Award date||18 Dec 2020|
|Publication status||Published - 2020|