Gamma-TiAl is an ordered intermetallic compound characterized by high strength to density ratio, good oxidation resistance, and good creep properties at elevated temperatures. However, it is intrinsically brittle at room temperature. This thesis investigates the potential for the use of grinding to process TiAl into useful shapes. Grinding is far from completely understood,
and many aspects of the individual mechanical interactions of the abrasive grit with the material and their effect on surface
integrity are unknown. The development of new synthetic diamond superabrasives in which shape and size can be controlled raises the question of the influence of those variables on the surface integrity.
The goal of this work is to better understand the fundamentals of the abrasive grit/material interaction in grinding operations.
Experimental, analytical, and numerical work was done to characterize and predict the resultant deformation and surface integrity on ground lamellar gamma-TiAl.
Grinding tests were carried out, by analyzing the effects of grit size and shape, workpiece speed, wheel depth of cut, and wear on the subsurface plastic deformation depth (PDD). A practical method to assess the PDD is introduced based on the measurement of the lateral material flow by 3D non-contact surface profilometry. This
method combines the quantitative capabilities of the microhardness measurement with the sensitivity of Nomarski microscopy. The scope and limitations of this technique are analyzed. Mechanical
properties were obtained by quasi-static and split Hopkinson bar compression tests. Residual stress plots were obtained by x-ray, and surface roughness and cracking were evaluated.
The abrasive grit/material interaction was accounted by modeling the force per abrasive grit for different grinding conditions, and
studying its correlation to the PDD. Numerical models of this interaction were used to analyze boundary conditions, and abrasive size effects on the PDD. An explicit 2D triple planar slip crystal
plasticity model of single point scratching was used to analyze the effects of lamellae orientation, material anisotropy, and
grain boundaries on the deformation.
| Identifer | oai:union.ndltd.org:GATECH/oai:smartech.gatech.edu:1853/6968 |
| Date | 20 August 2004 |
| Creators | Murtagian, Gregorio Roberto |
| Publisher | Georgia Institute of Technology |
| Source Sets | Georgia Tech Electronic Thesis and Dissertation Archive |
| Language | en_US |
| Detected Language | English |
| Type | Dissertation |
| Format | 22131435 bytes, application/pdf |
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