Yield strength of flange

The yield strength of flange is the yield limit of metal material when yield occurs,that is, the stress to resist micro plastic deformation.For the metal materials without obvious yield phenomenon, the stress value of 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 permanently invalid and cannot be recovered. For example, the yield limit of low carbon steel is 207mpa. When the external force is greater than this limit, the part will have permanent deformation. If it is smaller than this limit, the part will return to its original appearance.

EN 1092 Q235 FF flat flanges

EN 1092 Q235 FF flat flanges

(1) for materials with obvious yield, the yield strength is the stress (yield value) at the yield point;

(2) for materials with no obvious yield phenomenon, the stress when the limit deviation of stress-strain linear relationship reaches the specified value (usually 0.2% of the original gauge distance). Generally used as the evaluation index of mechanical properties of solid materials, it is the practical use limit of materials. Because after the stress exceeds the yield limit of the material, necking occurs and the strain increases, which causes the material to be damaged and cannot 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 maximum and minimum stresses in this stage are called the upper yield point and the lower yield point respectively. Because the value of the lower yield point is relatively stable, it is used as the index of material resistance, which is called yield point or yield strength (REL or Rp0.2).

ASME B16.5 ASTM A105N RTJ weld neck flanges

ASME B16.5 ASTM A105N RTJ weld neck flanges

Some steels (such as high carbon steel) have no obvious yield phenomenon. The yield strength of the steel is usually taken as the stress when a little plastic deformation (0.2%), which is called the conditional yield strength.

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