Toroid-shaped soft magnetic powder cores (SMCs) were produced by cold pressing of the commercial sendust alloy powders. The characteristics of the commercial sendust alloy powder and the effect of compaction pressure on the magnetic properties, i.e., effective permeability μe, quality factor Q, DC-bias properties and volume power loss of sendust alloy powder cores were investigated. The results showed that the sendust alloy powder core with shaping pressure of 1932 MPa, annealing temperature of 953 K for 1 h and dielectric content of 0.96% presents the optimum magnetic properties with an effective permeability of 90, a total loss of 386 mW/cm3 at f=50 kHz and Bm=0.1 T, a DC-bias property of 64% at H=50 Oe.

The processing equipment for near-net shape technology of materials is introduced in the paper. According to analysis of industrialized processing equipment and technology testing equipment for difficult-to-cut alloy materials, combined with difficulties in strip casting and features of difficult-to-cut alloy materials, the processing equipment for difficult-to-cut alloy materials near-net shaping is developed, thus realized single machine-shaping from molten steel to cold rolling product, and improved near-net shape manufacturing technology of materials.

In the paper, development and research on near-net shape technology is mainly introduced, including ultra-rapid quenching process for 6.5%Si high silicon steel strip and casting technology for thin silicon steel strip. The effects on fabrication property of the above products are analyzed and main processes are investigated. Preparation of silicon steel strip by near-net shape technology is prospected, too.

An Fe-6.5 wt. % Si steel sheet with a final thickness of 0.30 mm was produced by twin roll strip casting and warm rolling process. The effects of casting, warm rolling and annealing process on microstructure, texture and magnetic properties were investigated with optical microscopy, X-ray diffraction and magnetic measurement. The microstructure evolution during preparation was shown as follows: columnar grain and a small amount of fine grain in center (as casted) elongated grains and a small amount of the shear bands along the rolling direction (as rolled) a relatively uniform recrystallized microstructure (as annealed). The texture evolution during preparation was shown as follows: {001} λ fiber texture (as casted) the significant α fiber texture and the weak, inhomogenous γ fiber texture (as warm rolled) the strong {001} λ fiber texture and weak, inhomogenous γ fiber texture (as annealed). The excellent soft magnetic properties were obtained with a very small P1.0/400of 10.751 W/kg and a very high B50up to 1.438 T at optimum annealing condition (1150 °C for 1 h). The research work was useful to develop electrical steel by twin roll continuous casting process.

A kind of environment-friendly Cr-free insulating coating for grain-oriented electrical steel is exhibited in this paper. The tensile stress and the magnetic properties for both Cr-free and Cr-containing insulating coating were measured. The results showed that the more the coating on the metal, the bigger the tensile stress produced. The contribution of the Cr-free insulating coating to the reduction in P1.7/50 varies from 0.092 to 0.192 W/kg, while the reduction in P1.7/50 by the Cr-containing insulating coating is from 0.066 to 0.177 W/kg, with the weight of the coating varies from 4 to 6.5 g/m2. In comparison with the traditional Cr-containing insulating coating, the Cr-free coating produces larger tensile stresses in the metal, thus leads to better magnetic properties, especially in the magnetic losses. Keywords: grain-oriented electrical steel, insulating coating, Chromium-free, magnetic property, tensile stress