Research On The Development Of Electropulsing Annealing Device And Its Treatment Process To The Hard-drawn Carbon Steel Wire

It is difficult to have a continuous multi-processing of the steel after cold-drawing process during the process of plastic deformation of metal, because of the internal dislocation formation and movement which leads to a work-hardening and results in hard and brittle materials. Therefore, the annealing treatment must be required for the post-Cold-drawn steel wire. The traditional annealing methods have some disadvantages, such as inefficient, large energy-consuming, pollution of the environment, as well as surface oxidation serious of the products, and so on, which because of its principle of annealing through thermal effect to achieve. In order to overcome the deficiencies of the traditional annealing methods, the paper will explore in depth a new annealing technology -electric pulse annealing treatment, and explore new methods which use the high-density pulsed electric treatment to replace the traditional treatment of the thermal effect.Firstly, the paper conducts deeply discussions of pulse power supply circuit structure, redesigns the power supply program, and develops a new type of pulse power with adjustable-current and frequency.PWM (Pulse Width Modulation) control strategy is used to achieve the adjustment of output voltage; using IGBT (Insulated-Gate Bipolar Transistor) high-frequency chopper control means to achieve power supply voltage regulator function. Aslo, this thesis thoroughly discusses the circuit design program of the device and its whole machine assembly. The eventually developed pulse power supply equipment can provide the maximum pulsed output current of 6000A, changes in pulse frequency range of 1 to 600Hz. Secondly, the paper presents the corresponding experimental program, carrying out the electric pulse annealing experiments to Q235 steel wire under different process conditions. And then makes a tensile strength, elongation and other mechanical properties testing to the original sample and samples which carry out annealing treatment under electric pulse. Observe the microstructure changes between the original sample and samples under electric pulse annealing treatment with metallographic microscope. Finally conduct a comparative analysis of mechanical properties and microstructure to the samples under traditional annealing. It is found through the analysis that the pull-out resistance of the wire is significantly decreased and the elongation is improved significantly after electric pulse treatment. So, it shows that high-strength pulse current treatment can make the mechanical properties of cold-drawn steel wire back to the soft-state level before drawing in a short time, to reach the similar effect with traditional annealing or even better.Finally, through metallographic analysis of microstructure, the paper carrys out exploratory research into the mechanism of pulse annealing process use Joule heating effect, magneto-plastic effect, electric plasticity theory and annealing theory for reference. It is found that pulse current can increase driving force of recrystallization nucleation and the existence of the magnetic field can enhance the capacity of dislocation slip which is useful to the recrystallization nucleation and grow up. The pulse current annealing can reduce the initial recrystallization temperature significantly, accelerate its recovery and recrystallization, and enhance the nucleation rate of recrystallization, so that the performance indicators of metal can be recoveried rapidly.The results show that the use of pulse current on the carbon steels can also play a role in softening annealing. Compared with traditional heating annealing, the use of pulse current annealing can increase the parameters of metal plasticity, reduce the times of middle annealing or even avoid, intensify the production process and improve the productivity significantly.