Abstract: Coercivity of a DT4E electromagnetic pure iron part after vacuum annealing exceeds the design requirements. In order to solve this problem, the DT4E electromagnetic pure iron was vacuum annealed at 860-1150 ℃ for 4 h to analyze the effects of annealing temperature, magnetic test ring size and impurity compositions in raw materials on the magnetic properties. The results show that with the increase of annealing temperature, the magnetic induction intensity B₂₅₀₀ changes as “M” type, the coercivity H_c changes as “V” type, and the change trend of maximum permeability μ_m is opposite to that of the coercivity. The optimum vacuum annealing temperature is 900 ℃,at which the magnetic induction intensity B₂₅₀₀ is 1.63 T, the coercivity H_c is 25.19 A/m, and the maximum permeability μ_m is 23.64 mH/m, all meeting the design requirements.Moreover, the size of the magnetic test ring has no significant effect on the measurement results of the magnetic properties of the DT4E electromagnetic pure iron. The content of impurity elements in raw materials has a great influence on magnetic properties. When the C content is higher, the permeability decreases and the coercivity increases, which easily leads to unqualified magnetic properties.

Key words: DT4E, electromagnetic pure iron, vacuum annealing, electromagnetic properties