The present book ‘Mathematical Modelling of Weld Phenomena 13‘ contains papers presented at the 13th International Seminar ‘Numerical Analysis of Weldability‘, which was held from September 26 to 29, 2021, at Schloss Seggau near Graz, Austria. This meeting was organised by the Institute of Materials Science, Joining and Forming of Graz University of Technology together with the working group ‘Mathematical Modelling of Weld Phenomena‘ of Commission IX of the International Institute of Welding (IIW).

The academic aim of these meetings is to publish authoritative, well-written, refereed and edited articles, which are presented in sufficient depth to enable the ready reproduction of the work and to serve as reference as well as teaching material.