Time of intensive development. Aleksandra Laska graduated from the Doctoral School | Gdańsk University of Technology

The promoter of the doctoral thesis of the scientist, entitled "Influence of friction stir welding technological parameters on the properties of the joints of selected aluminum alloys" is prof. Marek Szkodo. The reviewers are Mirosław Czechowski, PhD, DSc, Eng., professor at the GMU (Gdynia Maritime University), prof. Lucjan Śnieżek, PhD, DSc, Eng. (Military University of Technology), prof. Agata Dudek, PhD, DSc, Eng. (Częstochowa University of Technology).

– My doctoral thesis concerns the impact of residual stresses and dislocation density on the mechanical and physicochemical properties of welds produced with a modern, innovative technology called Friction Stir Welding – explains Aleksandra Laska.

Friction Stir Welding is a method of friction welding in the solid state, in which, using a special rotary tool, it is possible to obtain joints with high mechanical properties, free from cracks and porosity. The process can be carried out on milling machines, specialized friction welding machines and robotic stations.

– In this method, the welding process involves mechanical mixing of materials. In the case of my research, these are aluminum alloys in the plasticized state. Through this mechanical agitation, residual stresses appear in the material. They are very common and cause many problems, especially in the traditional welding process. They can lead, for example, to cracking of the material. In my work, I analyzed the process parameters, that is the rotational speed, linear speed or tool geometry and their impact on the mechanical or electrochemical properties of the material.

When aluminum alloys are subjected to the welding process, defects may occur easily. In addition, during the solidification of the material melted under the influence of the supplied energy, hydrogen is released in the form of gas bubbles, which can stop in the cooling metal, causing its porosity. The use of the FSW method, that is friction welding, eliminates these risks to a large extent.

– In my research, I focus on aluminum alloys, because it is a material that, together with other composites, is slowly displacing steel on the industrial market. Steel is a heavy material, and weight plays an important role in the shipbuilding and, above all, aviation industry, emphasizes Aleksandra Laska.

In the near future, the scientist wants to continue the research started in her doctoral thesis. From October, she starts working full-time at the MEST Faculty in the Department of Machine Technology and Production Automation.

–  The period of doctoral studies was very fruitful for me - says the doctoral student - Apart from the studies, I was also employed at the Faculty as a technical worker. Thanks to this, I learned how to use machines and equipment, so I am completely independent in my research because the machine laboratory has no secrets from me. Third-cycle studies are also a great opportunity to travel abroad and make contacts. Unfortunately, I studied during the pandemic and the period of limited mobility, but despite this, I managed to complete an internship in Italy, Slovakia and Germany, and participate in conferences in Bulgaria and Portugal.