Heat treatment process of cold formed spring

Heat treatment of cold formed springs:
   Spring parts with a diameter less than 8mm are commonly formed by cold-drawn steel wire and cold-rolled. The cold-drawn steel wire manufacturing process and subsequent heat treatment are mainly the following three categories:
  1) Lead bath treated cold drawn steel wire
First, the steel wire is continuously drawn three times, the total deformation reaches 50%, and then it is heated to a temperature above ac3 to make it austenitized, and then treated at an intermediate temperature in a lead bath at 450-550°C to transform austenite into a sorbite structure .The yield strength is 1600mpa. After the cold coil is formed, it can be annealed at 200-300℃ to eliminate the stress. Dongguan Spring
   2) Steel wire in annealed condition
   The steel wire is drawn to the specified size, and then annealed. After the softened steel wire is cold rolled, it needs to be quenched and tempered at medium temperature to obtain the required mechanical properties.
  3) Oil quenched and tempered steel wire
After the steel wire is drawn to the treated size, it is oil quenched and tempered. The strength of this type of steel wire is not as good as that of the lead bath treated steel wire, but the performance is uniform and the cost is lower. After the cold coil is formed, it is subjected to stress relief treatment.