After cold-drawn steel pipe is processed, the plasticity, strength and hardness of cold-drawn steel pipe metal are reduced and increased due to the flattening and elongation of grains (see Fig. 1), lattice distortion and grain deformation (see Fig. 2). This phenomenon is called work hardening. Work hardening has very important practical significance. It is one of the methods of strengthening metals (increasing strength), especially for pure metals and metals that can not be strengthened by heat treatment. For example, the high wear resistance of tank track and lining plate of ore crusher, the high elasticity of cold spring after winding and the high strength of cold drawn steel pipe are all the results of work hardening. In addition, work hardening also creates conditions for cold working production of metals. Because the metal can harden to a certain degree in the cold working process and can not continue processing, under certain conditions, it will not cause fracture due to deformation. 加工硬化提高了变形抗力，给冷拔钢管金属的继续加工带来困难。为了消除加工硬化必须在加工过程中进行专门的热处理，冷拔钢管金属经再结晶软化之后才能继续进行加工。
Work hardening improves the deformation resistance and brings difficulties to the continuous processing of cold-drawn steel pipe metals. In order to eliminate work hardening, special heat treatment must be carried out in the process of processing, and the cold-drawn steel tube metal can continue to be processed only after recrystallization and softening.
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