A study towards the development of the laser shock peening technology for an eskom power station low pressure steam turbine blade: to also compare the impact of laser shock peening without coating against shot peening treatment on 12% CR steel

Simple item page
dc.contributor.authorKuveya, Khanyisile Rose
dc.date.accessioned2019-07-17T08:25:47Z
dc.date.available2019-07-17T08:25:47Z
dc.date.issued2018
dc.descriptionA dissertation submitted in fulfillment of the requirements for the degree of Master of Science in Engineering to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, 2018en_ZA
dc.description.abstractThe root section of a turbine blade is the most critical part as it forms the structural bond of the turbine blade to the shaft. If not maintained correctly the blade could fail catastrophically due to high and low cycle fatigue, stress corrosion cracking as well as corrosion fatigue. The sources of loading on the blades vary from normal operation, excitation of natural frequencies during transient occasions and overloads during statutory testing. Different surface modification technologies can be put in place to improve blades in-service performance. The present study is aimed at comparing previous results achieved from Shot Peening (SP) of an equivalent turbine blade to those achieved by Laser Shock Peening without coating (LSPwC).The SP data which is used for comparison is from the work and study done to optimise the SP of a 12Cr steel steam turbine blade. It is expected that LSPwC processing of the blade will result in a reduction in mean surface roughness (Ra), and deeper compressive residual stresses than the conventional SP processing. The focus of this investigation is also to determine the effects of LSPwC laser and processing parameters, such as laser intensity, laser spot size, coverage, water layer, and possibly laser wavelength on the X12CrNiMo12 high strength steel target material. Segments of an ex-service turbine blade, 20x20mm by 10mm thickness, processed at the CSIR National Laser Centre under various LSPwC parameters were analysed as follows: composition properties confirmed by spark tests; surface integrity assessed by SEM and 3D roughness mapping; microstructure; residual stress measurements by laboratory X-ray Diffraction. The experimental results helped in optimizing the LSPwC parameters for the X12CrNiMo12, before applying LSPwC to the more complex geometry of the blade root. This study then allowed for the determination of which peening process is most suited for turbine components.en_ZA
dc.description.librarianMT 2019en_ZA
dc.format.extentOnline resource (vi, 111 leaves)
dc.identifier.citationKuveya, Khanyisile Rose (2018) A study towards the development of the laser shock peening technology for an Eskom power station low pressure stream turbine blade application: to also compare the impact of laser shock peening without coating against shot peening treatment on 12%Cr steel, University of the Witwatersrand, Johannesburg, https://hdl.handle.net/10539/27685
dc.identifier.urihttps://hdl.handle.net/10539/27685
dc.language.isoenen_ZA
dc.subject.lcshLaser peening
dc.subject.lcshMetallurgy--Laser use in
dc.titleA study towards the development of the laser shock peening technology for an eskom power station low pressure steam turbine blade: to also compare the impact of laser shock peening without coating against shot peening treatment on 12% CR steelen_ZA
dc.typeThesisen_ZA
Files
Original bundle
Now showing 1 - 2 of 2
No Thumbnail Available
Name:
Abstract_Final Submission_KR Kuveya_594354.pdf
Size:
10.85 KB
Format:
Adobe Portable Document Format
Description:
Download
No Thumbnail Available
Name:
Final submission_KR Kuveya 594354.docx.pdf
Size:
6.71 MB
Format:
Adobe Portable Document Format
Description:
Download
License bundle
Now showing 1 - 1 of 1
No Thumbnail Available
Name:
license.txt
Size:
1.71 KB
Format:
Item-specific license agreed upon to submission
Description:
Download
Collections
ETD Collection