Abstract
dc:description.abstractA study has been made of the changes in the surface topography, microstructure, micro and macro residual stresses and carbon content, occurring in case-carburised steel disc specimens as a result of rolling contact loading. The study of the surface topography of the run specimen using direct and indirect plastic replica technique and the electron microscope reveals cracks in the roughened area of the specimen and that excessively carburised specimen shows less coarsening. Optical and electron microscopic observation of the electropolished specimens indicate that the cracks originate in the sub-surface region. Measurements of the macro-residual stresses due to rolling contact, in pure rolling and combined rolling and sliding show the development of compressive stresses with a maximum at the surface and another at about the depth of the maximum Hertz stress. The study of the X-ray diffraction peak shapes indicate peak sharpening which is running time and specimen depth dependent. Determinations have been made of the amount of austenite produced due to rolling contact loading (Flash temperature) using X-ray diffraction technique. Measurements of carbon gradient using spectrographic technique suggest a carbon depletion in the surface layers. Finally, the possible correlation of these changes microstructure residual stress, carbon diffusion/precipitation, and phase transformation, with the rolling contact behaviour of normal and excessive carburised disc specimens is investigated.
Degree
thesis:*- Name dc:type.qualificationname
- PhD
- Level dc:type.qualificationlevel
- Doctoral
- Grantor dc:publisher.institution
- De Montfort University
- Year dc:date.issued
- 1976
Author and committee
dc:creator, dc:contributor.*- Author dc:creator
-
- Siddiqui, Ali Mohammed