In addition, the introduction of a higher amount of mobile dislocations through temper rolling can remove the discontinuous yielding. However, the last action is often not considered as an invariable solution for eliminating the yield point elongation in mild steels because after aging, the interstitial atoms pine the dislocations and form the Cottrell atmosphere [3, 4].
Continuous yielding took place in the steels subjected to a rolling reduction of 60%, while the yield point phenomenon (discontinuous yielding) occurred in the rolled steels with a rolling reduction of 30%.
T) exhibited discontinuous yielding for some or all of the specimens tested.
In case of discontinuous yielding, it is common practice to report the minimum value of engineering stress during the period of discontinuous yielding, which is known as lower yield strength ([[sigma].sub.LYS]), as the value of yield strength.
We therefore decided to use in this investigation only [[sigma].sub.YS0.2(est)] values for all steels, except when discontinuous yielding was observed.
Wang, Effects of strain rate and notch on acoustic emission during the tensile deformation of a discontinuous yielding
In some specimens the structure of the strain increment associated with discontinuous yielding is quite repeatable.
The discontinuous yielding in build 2 Vertical specimens is longer, and its structure differs from the horizontal specimens of all three builds.
Heat treatment reduces the discontinuous yielding region in the vertical specimens, but does not change the general shape.
The low-strain structure of the stress-strain curve in the discontinuous yielding region is caused by the formation and propagation of two Luders bands, which nucleate at the ends of the gauge length and propagate until they meet in the center of the specimen.
The stress-strain curves exhibit several artifacts that are known [28,29] to be created by the interaction of the discontinuous yielding or Luders bands, the specimen geometry and surface finish, and the geometry of the extensometer.
The second S-type instability is clearly associated with negative strain-rate sensitivity, giving rise to discontinuous yielding
known as the Portevin-Le Chatelier effect.