Glass substrate for flexible display and display device including the same

A glass substrate comprising:

• a first portion which corresponds to a flat portion of a flexible display;
• a second portion which is adjacent to the first portion and corresponds to a bendable portion of the flexible display which extends from the flat portion;
• a third portion connecting the first portion and the second portion to each other;
• a chemically strengthened thickness portion of the glass substrate extended from an outer surface of the glass substrate, at each of the first portion, the second portion and the third portion, which defines a depth of layer;
• wherein
• each of the first portion, the second portion and the third portion of the glass substrate has an average thickness;
• each of the first portion, the second portion and the third portion of the glass substrate has an average depth of layer,
• the average thickness of the glass substrate at the first portion is greater than the average thickness of the glass substrate at the second portion,
• the average depth of the depth of layer at the first portion is in a range of about 7% to about 18% of the average thickness of the glass substrate at the first portion,
• the average depth of the depth of layer of at the second portion is in a range of about 15% to about 20% of the average thickness of the glass substrate at the second portion, and
• a radius of curvature at the second portion of the glass substrate is about 0.4 millimeter or less.