Evolution of Cementite in Hypoeutectoid Steel Wire during Cold Work Hardening in Rolling Process

Using Φ1.80mm steel wire drawn from Φ6.5mm steel wire was drawn to Φ1.80mm as raw material. Using cold three-rolling process, we got flat wire which size was 0.75mm x 3.17mm by cold three-pass rolling process. Researches shown that 60 steel wire has good plastic deformation ability during cold work processing. The tensile strength and micro-hardness shows linear growth characteristics in the early first stage of cold rolling, then they have exponential growth characteristics in later rollings. That is because in the first rolling process the cementite eventually dissolved in large quantities as the ferrite is turned, deformed, refined and broken. The solution mechanism of cementite is the Gibbs-Thomson effect, i. e. interface energy mechanism.