温度・粘度
strain point
Japanese: 歪点
The temperature at which glass effectively becomes a solid (log η ≈ 14.5). Below this temperature, the glass will not deform except due to thermal shock. / Note: This is 40–50°C lower than the slow-cooling point. Passing through this range rapidly does not relieve stress.
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The strain point is the temperature at which glass effectively becomes a solid, corresponding to a viscosity of log η ≈ 14.5. At temperatures below this point, the glass undergoes almost no deformation except in the case of thermal shock.
This temperature is approximately 40–50°C lower than the slow-cooling point, and even if this range is passed through quickly, the new stresses will not be relieved.
This entry is written in Japanese by Rei Chikaoka and translated for readers outside Japan. If something reads oddly, the original is the source of truth.