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Residual Stresses in Machined MgO Crystals
Author(s) -
G. E. BERNAL,
KOEPKE B. G.
Publication year - 1973
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1973.tb12441.x
Subject(s) - materials science , residual stress , composite material , diamond , grinding , ultimate tensile strength , brittleness , surface integrity , diamond grinding , burnishing (metal) , grinding wheel , polishing
The residual stresses introduced in MgO crystals by grinding on {100} surfaces in 〈100〉 directions were measured using photoelastic techniques. Grinding was conducted with two wheels; a 100‐grit diamond wheel removed material by brittle fracture, and a 46‐grit alumina wheel caused plastic flow and burnishing. Both wheels introduced a discrete, highly deformed layer adjacent the machined surface. In all cases the machined surfaces were under a residual tensile stress which 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 became tensile again within 0.5 mm of the ground surface, whereas the subsurface stresses in crystals ground with the diamond wheel remained compressive to distances ≥1 mm. These residual stress distributions are discussed in terms of a simple model based on the superposition of mechanically and thermally induced stresses.