Contact residual stress relaxation in soda-lime glass Part II. Aspects relating to strength recovery

• Strength recovery of Vickers indented soda lime glass was measured and compared after annealing at two temperatures: one below and one above T, The atomic force microscope was used to study the cracks. At 540 degrees C, no changes were observed in crack morphology either below the surface or on the surface relative to the pre-anneal state. At 630 degrees C, both sub-surface and surface crack morphology changes were observed. The trends in strength recovery were compared with residual stress relaxation as measured by a new method of stress estimation based on nanoindentation elastic response. At short hold times at 630 degrees C, and regardless of the length of hold time at 540 degrees C, strength recovery of only similar to 30% was measured while at moderately long hold times at 630 similar to C, strong recovery of fracture strength, similar to 132% was measured. Trends in strength recovery above T. are shown to match those of crack tip radius instead of trends in stress relaxation across the residual stress field.

Nyckelord

nanoindentation

glass

stress relaxation

indentation cracks

decay

sharp

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