Elastic and Inelastic Strain  
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The graph plots stress in p s i versus strain in inch per inch. The horizontal axis ranges from 0 to 0.1 and the vertical axis ranges from 0 to 80,000. The graph starts at the bottom left of the viewing window at the origin, goes up and to the right with constant steepness till the point (0.050, 50,000). The graph then goes up and to the right with a reduced positive slope till (0.1, 60,000). A straight line is drawn passing through (0, 0) and (0.0040, 43,700) and it overlaps the linear portion of the curve. The portion of the curve between (0, 0) and (0.086, 59,000) is highlighted. Points A and B are marked on the curve at (0.04, 43,700) and (0.086, 59,000). The portion of the curve between the origin and point A is labeled elastic strain and the portion of the curve between the points A and B is labeled inelastic strain.

The strain between origin O and the proportional limit A is termed elastic strain. This strain will be fully recovered when the stress is removed from the material.