tensile strength: When the steel yield to a certain extent, due to internal grain rearrange its resistance to deformation capacity again increased, this time deformation has developed rapidly, but can only increase as the stress increases until the stress reaches the maximum value. Since then, the ability of steel to resist deformation is significantly reduced, and large plastic deformation occurs in the weakest here to try cross-section is rapidly diminishing, the phenomenon of necking until the fracture process. Steel by tension fracture of the maximum stress (b point corresponding value) is called the ultimate strength of tensile strength.
yield strength: when the stress exceeds the elastic limit, deformation increases rapidly, in addition to the elastic deformation, but also produce some plastic deformation. Plastic strain when the stress reaches the point B, a sharp increase in the curve of a volatile small platform, a phenomenon known as the yield. Maximum and minimum stress of this stage are called the upper yield point and lower yield point. The yield point value is relatively stable, as the material resistance index, called the yield point or yield strength.
Some steel products (such as high-carbon steel) no obvious yield phenomenon, usually a small amount of plastic deformation (0.2%) of stress as the yield strength of steel, called the conditions the yield strength.
First explain the deformation of material force. Deformation of the material is divided into elastic deformation (external revocation can restore the original shape), and plastic deformation (external revoked can not be restored to its original shape, shape change)
Yield strength: When the material of the stress exceeds the elastic limit, deformation increases rapidly, in addition to the elastic deformation, but also produce some plastic deformation. Plastic strain when the stress reaches a value a sharp increase in the curve of a volatile small platform, a phenomenon known as the yield. Maximum and minimum stress of this stage are called the upper yield point and lower yield point. The yield point value is relatively stable, as the material resistance index, called the yield point or yield strength.
tensile strength: Tensile strength refers to the material under tensile stress, the maximum uniform plastic deformation stress.