Master thesis: Post-weld treatment of welded structures for automotive and

The metals research institute Swerim conducts needs-based industrial research and development concerning metals and their route from raw material to finished product. Swerim has 190 co-workers in two locations in Sweden - Luleå and Stockholm.

Goal
The goal of this master thesis work is to create a state-of-the-art report regarding manual PWT (post-weld treatment methods, TIG, HFMI And Burr-grinding) process parameters and their influence on fatigue performance of welded structures. The results will be verified against currently available recommendations for PWT and by experimental work within the master thesis work.
 
Background
Locally applied post-weld treatment (PWT) methods such as TIG-remelting and Burr-grinding are used (manually) in manufacturing industries for improvement purposes and have shown greatly improved fatigue life of welded structures when correctly applied. The more recent High Frequency Mechanical Impact (HFMI) methods enable an even greater fatigue life enhancement and also the possibility to utilise steels with higher tensile strength in fatigue loaded components. Hence HFMI enables significant component optimisation, further improved products and increased competitiveness by reduced weight of welded components, and reduced scrapping.
The goal of this master thesis work will be to gather published work regarding the PWT process parameters and weld geometry and their influence on fatigue performance in a state-of-the-art report. The results in the state-of-the-art report will also be compared to current recommendations for PWT issued by the International Institute of Welding (IIW) and verified by extensive experimental work. In the experimental work, the master thesis student will perform welding trials and PWT of welded samples. The welded and PWT samples will be evaluated by laser scanning (Weld geometry) and fatigue testing. In the experimental work the manufacturing productivity of the various PWT methods (TIG, HFMI and Burr-grinding) will also be investigated through performing a process study and cost assessment. This process study will identify key process steps, both non-value adding and value-adding, and establish lead times for the various PWT methods within the master thesis work. To enable an accurate process study, the recording of the experimental work is to be thoroughly planned to best catch required processing steps and lead times. Performed process study will be the basis for a final cost assessment, where established process steps and lead times will be coupled to involved costs and identify important cost drivers.
 
Thesis description
* Theoretical background
- Gather published data, regarding PWT (TIG, HFMI and Burr-grinding) process parameters and their influence on fatigue performance. Compile published data in a state-of-the-art report.
* Experimental Work
- Welding of specimens intended for PWT, in robot cell at Swerim.
- Perform manual PWT (Burr-grinding) of welded samples 
* Manual PWT (TIG and HFMI) will be performed by external party, but the results regarding process parameters, laser scan geometry and time/productivity will be included to this master thesis.
- Perform Laser scanning (Weld geometry) of welded and PWT samples and compile geometric data of the samples.
- Process study, recording process steps and lead times for the various studied PWT methods.
* Assess costs and find key cost drivers of the various PWT methods as a function of performed process study.
* Perform comparisons from state-of-the-art report to current international recommendations (IIW) and verification by the extensive experimental work.

We are looking for you that are at the end your Master of Science studies, preferably in Material science, Solid mechanics, Mechanical engineering. Strong interest in Joining, Welding, Material, Robotics is an advantage. Knowledge of welding engineering, solid mechanics and coding would be preferable, but not required. We want you to be able to take own initiatives, be comfortable with addressing challenging problems, and have good communications skills in both written and spoken English. The proposed mater thesis work is both theoretical and experimental (Welding lab), with a rough estimate of 3 month theoretical state-of-the-art and reporting and 2-month experimental work.
 
The master thesis is connected to an ongoing Vinnova research project.
 
Location and time
The thesis work will be performed at Swerim in Kista with a proposed start in early 2021.
 
Performing master thesis work at Swerim will give you the experience of working as a researcher in a stimulating environment with modern laboratories, in a team with skilled researchers developing tomorrow’s technologies for industry. You will have the possibility to meet and connect with industrial partners and to understand their needs and interest. Swerim rewards the student with 50 000 SEK for an approved master thesis (30 hp).
 
Contact
Rickard Aldén, Senior researcher, rickard.alden@swerim.se, +46 (0)722 23 95 45