The difference between hot deformation and cold deformation of casters

Thermal deformation of casters refers to the plastic deformation of metal materials above their recrystallization temperature. During the thermal deformation process of metal, due to the high temperature and high atomic mobility, the hardening caused by the deformation is immediately eliminated by recrystallization, so it has the following characteristics: thermal deformation causes shrinkage, pores or voids inside the metal material to be compacted , the coarse (dendritic) grain structure is refined by recrystallization, making the internal structure of the metal dense and fine, and the mechanical properties (especially toughness) are significantly improved and enhanced. Metal always maintains good plasticity during thermal deformation, allowing the workpiece to undergo a large amount of plastic deformation. And because the yield strength of metal is low at high temperatures, its deformation resistance is low and it is easy to deform.

Cold deformation of casters means that the temperature of the metal during plastic deformation is lower than the recrystallization temperature of the metal. The characteristic of cold deformation is that the metal has work hardening after deformation, that is, the strength and hardness of the metal increase and the plastic toughness decreases. Moreover, the products made by cold deformation have high dimensional accuracy and good surface quality. For those metal components that cannot or are not easy to use heat treatment to improve strength and hardness, especially thin-walled and slender parts, it is effective and economical to use work hardening of the metal during the forming process to improve the strength and hardness of the component. For example, various cold stamping parts, cold rolled and cold extruded profiles, cold rolled springs, cold drawn wires, cold heading bolts, etc. It can be seen that cold deformation processing is widely used in various industries. Products processed through cold deformation, including some complex parts or parts with higher requirements, need to be treated with low-temperature tempering to eliminate internal stress but retain work hardening. Due to the work hardening phenomenon during cold deformation, the plasticity of metal materials deteriorates, making further plastic deformation difficult. Therefore, cold deformation requires heavy-duty and high-power equipment; the surface of the processed blank is required to be clean, free of oxide scale, and smooth. In addition, work hardening increases the resistance at the deformation point of the metal and reduces the corrosion resistance.