According to the characteristics of the cold heading process, the following requirements are put forward for the mechanical properties of steel:

1) The yield strength Re and deformation resistance should be as low as possible, so that the unit deformation force can be reduced accordingly to extend the mold life;

2) The cold deformation performance of the material should be good, that is, the material should have good plasticity and low hardness, so that it will not cause cracking under large deformation degrees. For example, when cold heading high-strength bolts, carbon steel with higher carbon content can be used, or low alloy steel with lower carbon content can be used. If the carbon content is increased, the hardness will increase, the plasticity will decrease, and the cold deformation performance will deteriorate. However, adding a small amount of alloying elements to steel with lower carbon content (such as adding a small amount of boron 10B21, 10B33 steel) can significantly improve the strength of the steel, thereby meeting the performance requirements of the product without damaging its cold deformation performance;

3) The lower the work hardening sensitivity of the material, the better, so as not to cause the deformation force during the deformation process to be too large. The work hardening sensitivity of the material can be reflected by the slope of the deformation resistance-strain curve. The larger the slope, the higher the work hardening sensitivity. For example, stainless steel 0Cr18Ni9 (SUS304) has the largest curve slope. The work hardening sensitivity of this material is relatively severe. As the degree of deformation increases, the deformation resistance increases sharply.

The mechanical properties of steel not only reflect the Rm, Re, A, Z and hardness of the original billet, but are not only affected by the chemical composition, macrostructure, microstructure, etc. of the raw material, but are also affected by the drawing and various processes during the material preparation process. Effect of heat treatment between processes.