Dissertation defence (Mechanical Engineering): MSc Saeid Parchegani Chozaki

MSc Saeid Parchegani Chozaki defends the dissertation in Mechanical Engineering titled “Laser welding of additively manufactured Alloy 718” at the University of Turku on 29 October 2026 at 12.00 (University of Turku, Publicum, Pub2, Assistentinkatu 7, Turku).

Opponent: Professor Michael Rethmeier (Technical University Berlin, Germany)

Custos: Professor Antti Salminen (University of Turku) 

Summary of the Doctoral Dissertation:

Many important components used in industries such as aerospace, energy, and nuclear power must operate safely under high temperatures and demanding conditions. New manufacturing methods, often called metal 3D printing, enable the production of complex parts more efficiently and with less material waste than traditional methods. One of the most commonly used materials for these applications is Alloy 718, a high-strength metal known for its durability and ability to perform in high-temperature environments.

Although metal 3D printing can create highly complex parts, many of these components still need to be joined together during manufacturing, maintenance, or repair. Welding is one of the most common ways of joining metal parts. However, parts made by 3D printing may respond differently to welding than conventionally manufactured parts because the printing process creates a unique internal structure within the material. Understanding these differences is important for ensuring that welded components remain strong, reliable, and safe in service.

This thesis investigates how 3D-printed Alloy 718 behaves during welding. The study focuses on how the material changes when exposed to the heat of welding and how these changes influence the strength and performance of the welded joint. Different welding conditions were examined to understand their effect on the quality of the weld.

To evaluate the welded joints, the research combined detailed material examinations with strength testing. This made it possible to identify how welding affects the material and which factors contribute to stronger and more reliable joints.

The findings improve our understanding of how metal 3D-printed components can be successfully welded for use in demanding industrial applications. The knowledge gained from this work can help manufacturers produce safer and more reliable parts for sectors where performance and reliability are critical. Ultimately, the research supports the wider use of metal 3D printing in the production of advanced engineering components and contributes to more efficient and sustainable manufacturing methods.