In practice, general structures are fabricated by a series of production processes such as cutting, welding/ joining, and residual stress relieving, etc. In thermal process such as cutting and welding, residual stresses are unavoidably generated in the components. Since residual stresses might affect the structural integrity and service life, the postprocessing heat treatment is usually applied to relieve the generated residual stress in structures. To assess the structural integrity, it is necessary to know the magnitude and distribution of residual stress during fabrication at the design stage.
The samples with designed size are obtained from a big plate by cutting. The generated residual stress in this stage is called initial residual stress. Then, the cut samples are heat treated (annealing) to remove this initial residual stress in some cases. After that, the specimens are welded and the welding residual stresses are generated in the components. Finally, the residual stress relieving is performed to eliminate residual stress. However, there is almost no systematically investigaztion yet to quantitatively show the variation of residual stress during the whole fabrication.
First of all, the designed geometry of samples will be cut and machined from a large plate. After that, the heat treatment will be performed. Then, these samples will be welded using tungsten inert gas welding without the addition of filler wire. Finally, the post-weld heat treatment is performed. Note that the residual stress in the components will be measured by using X-ray diffraction at each stage.
The scope of the work is scalable and therefore allows for a bachelor’s thesis, student research project, and master’s thesis. A detailed assignment can be requested from the supervising research assistant. The time for familiarization is given under supervision.
The work can start immediately.
