What is the yield strength of flange?
Yield strength of flange
It is the yield limit of metal material when yielding phenomenon occurs, that is, the stress resisting micro plastic deformation. For metal materials without obvious yield phenomenon, the stress value which produces 0.2% residual deformation is defined as its yield limit, which is called conditional yield limit or yield strength.
The external force greater than the yield strength will make the parts permanent failure and cannot be restored. For example, if the yield limit of low carbon steel is 207mpa, when the external force greater than this limit, the part will produce permanent deformation, less than this, the part will return to its original appearance.
(1) For the material with obvious yield phenomenon, the yield strength is the stress at the yield point (yield value);
(2) The stress at which the limit deviation from the stress-strain linear relationship reaches the specified value (usually 0.2% of the original gauge length) for materials with unobvious yield. Generally used as the evaluation index of mechanical properties of solid materials, it is the actual use limit of materials. Because when the stress exceeds the yield limit of the material, necking will occur and the strain will increase, which will destroy the material and can not be used normally. When the stress exceeds the elastic limit and enters the yield stage, the deformation increases rapidly. At this time, in addition to the elastic deformation, there are also some plastic deformation. When the stress reaches point B, the plastic strain increases sharply and the stress-strain fluctuates slightly, which is called yield. The large and small stresses in this stage are called upper yield point and lower yield point respectively. Because the value of lower yield point is relatively stable, it is called yield point or yield strength (REL or Rp0.2) as an index of material resistance.
Some steels (such as high carbon steel) have no obvious yield phenomenon. The yield strength of the steel is usually determined by the stress when a small amount of plastic deformation (0.2%) occurs, which is called the conditional yield strength.
The next article will introduce the determination of flange yield strength and the factors affecting the yield strength.