How to solve the necking phenomenon of stamping and drawing parts

How to solve the necking phenomenon of stamping and stretching parts? First, we need to know the reason for this phenomenon: the reduction of cross-sectional area caused by necking is one reason, and the other reason is the fracture of the specimen on the tensile surface and inside

the resistance depends on the small cross-sectional area of a specimen (of course, the crack also reduces the actual cross-sectional area). That is because the material has gone through several stages from elastic deformation to plastic deformation and then to failure. Necking indicates plastic deformation of the material

tensile strength:

when the steel yield to the degree, due to the rearrangement of internal grains, its resistance to deformation is improved again. At this time, although the deformation develops rapidly, it can only increase with the increase of stress until the stress reaches a large value. Since then, the ability of steel to resist deformation is significantly reduced, and large plastic deformation occurs at the weak part, where the cross section of the specimen is reduced and necking phenomenon occurs until fracture failure. The large stress value (corresponding value of point B) before tensile fracture of steel is called strength or tensile strength

yield strength:

when the stress exceeds the elasticity, the deformation increases rapidly. At this time, in addition to elastic deformation, some plastic deformation is also produced. When the stress reaches point B, the plastic strain increases sharply and a fluctuating small platform appears in the curve. This phenomenon 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 as the index of material resistance