Residual Stresses in Machined Magnesium Oxide Crystals.
HONEYWELL INC BLOOMINGTON MINN CORPORATE RESEARCH CENTER
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The residual stresses introduced in magnesium oxide crystals by grinding on 100 surfaces in 100 directions were measured using photoelastic techniques. Grinding was carried out with two wheels, one removed material by brittle fracture and the other by plastic flow and burnishing. Both wheels introduced a discrete, highly deformed layer adjacent to the machined surface. In all cases the machined surfaces were under a residual tensile stress which reversed and became compressive within the deformed region. Beneath the deformed layer the residual stress patterns were distinctly different. In crystals ground with the alumina wheel, the stresses reversed again and became tensile within 0.5 mm of the ground surface whereas the subsurface stresses in crystals ground with the diamond wheel remained compressive to distances of 1mm or greater. These different residual stress distributions are discussed in terms of a simple model based on the superposition of mechanically and thermally induced stresses. Author
- Ceramics, Refractories and Glass