:: See stress-strain curve : in theory, a material will undergo pure elastic deformation up to the yield point, then pure plastic deformation until failure.
32.
After unpinning, dislocations are free to move in the crystal, which results in a subsequent lower yield point, and the material will deform in a more plastic manner.
33.
Once a dislocation has become pinned, a small extra force is required to unpin the dislocation prior the yielding, producing an observed upper yield point in a stress strain graph.
34.
A "'yield strength "'or "'yield point "'is the elastically and will return to its original shape when the applied stress is removed.
35.
In the three-dimensional principal stresses ( \ sigma _ 1, \ sigma _ 2, \ sigma _ 3 ), an infinite number of yield points form together a yield surface.
36.
Leaving the sample to age, by holding it at room temperature for a few hours, enables the carbon atoms to rediffuse back to dislocation cores, resulting in a return of the upper yield point.
37.
The second graph is the representation of the steel sheet that has undergone the cold-reducing ( hard rolling ) during manufacturing process, therefore it does not exhibit a yield point with a yield plateau.
38.
When elongating a fastener prior to reaching the yield point, the fastener is said to be operating in the elastic region; whereas elongation beyond the yield point is referred to as operating in the plastic region of the bolt material.
39.
When elongating a fastener prior to reaching the yield point, the fastener is said to be operating in the elastic region; whereas elongation beyond the yield point is referred to as operating in the plastic region of the bolt material.
40.
After the yield point, ductile metals undergo a period of strain hardening, in which the stress increases again with increasing strain, and they begin to neck, as the cross-sectional area of the specimen decreases due to plastic flow.
