A magnetic core includes alloy phases 20 each made of Fe-based soft magnetic alloy grains including M1 (wherein M1 represents both elements of Al and Cr), Si, and R (wherein R represents at least one element selected from the group consisting of Y, Zr, Nb, La, Hf and Ta), and has a structure in which the alloy phases 20 are connected to each other through a grain boundary phase 30. In the grain boundary phase 30, an oxide region is produced. The oxide region includes Fe, M1, Si and R and further includes Al in a larger proportion by mass than the alloy phases 20.

A magnetic core has a structure in which alloy phases 20 each including Fe, Al, Cr and Si are dispersed and any adjacent two of the alloy phases 20 are connected to each other through a grain boundary phase 30. In this grain boundary phase 30, an oxide region is produced which includes Fe, Al, Cr and Si, and includes Al in a larger proportion by mass than the alloy phases 20. This magnetic core includes Al in a proportion of 3 to 10% both inclusive by mass, Cr in a proportion of 3 to 10% both inclusive by mass, and Si in a proportion more than 1% and 4% or less by mass provided that the sum of the quantities of Fe, Al, Cr and Si is regarded as being 100% by mass; and includes Fe and inevitable impurities as the balance of the core.

This non-grain-oriented electrical steel sheet is a non-grain-oriented electrical steel sheet including a silicon steel sheet as a base material, wherein the silicon steel sheet has a predetermined mechanical property depending on a direction with respect to a rolling direction, and the difference between a maximum value and a minimum value of diameters of circular holes after punching with a substantially circular die is 0.20% or less of the average value of the maximum value and the minimum value.

Methods for producing non-oriented electrical steel sheets comprising steps including hot rolling a slab having a chemical composition comprising C: not more than 0.01 mass %, Si: not more than 6 mass %, Mn: 0.05-3 mass %, P: not more than 0.2 mass %, Al: not more than 2 mass %, N: not more than 0.005 mass %, S: not more than 0.01 mass %, Ga: not more than 0.0005 mass %, and the remainder being Fe and inevitable impurities, pickling without conducting hot band annealing or after conducting hot band annealing or self-annealing, subjecting to one or more cold rollings including an intermediate annealing therebetween and a finish annealing, and forming an insulation coating, an average heating rate from 500 to 800? C. in the heating process of the finish annealing is not less than 50? C./s, whereby a non-oriented electrical steel sheet having excellent magnetic properties is obtained even if hot band annealing is omitted.

Provided is a method for manufacturing a magnetostrictive torque sensor shaft mounting a sensor portion of a magnetostrictive torque sensor. The method includes conducting heat treatment on a shaft material including chrome steel or chrome-molybdenum steel by carburizing, quenching and tempering, and conducting shot peening on the shaft material after the heat treatment at least on a position where the sensor portion is to be mounted. The shot peening is conducted by firing shot with a particle size of not less than 0.6 mm and a Rockwell hardness of not less than 60 at a jet pressure of not less than 0.4 MPa for a jet exposure time of not less than 2 minutes.

Severe mechanical deformation in addition to thermal processing can be used to produce microstructural refinement in iron-cobalt-vanadium alloys. As an example, significant grain refinement through Equal Channel Angular Extrusion (ECAE), also known as Equal Channel Angular Pressing (ECAP), at high temperatures was demonstrated in bulk Hiperco soft magnetic alloy. The ECAE material exhibited high strength levels comparable to Hiperco sheet and the ductility was higher than heat treated conventional bar with large grain size. The increase in ductility was attributed to small grain size and the disordered phase that may co-exist with the ordered phase. In addition, the ECAP material also displays good magnetic properties, with relatively high magnetic saturation as shown in the B-H curve. The heat treatment after ECAP improves magnetic performance, with some tradeoff in mechanical properties. Therefore, with proper choice of post-ECAP heat treatment, an optimum combination of mechanical and magnetic performance can be achieved for a desired application, such as in solenoid switches, electric motors, and generators.

A NdFeB magnet containing cerium and a manufacturing method thereof are provided. The manufacturing method includes steps of: refining a part of raw materials pure iron, ferro-boron, and rare earth fluoride in a crucible, adding a rest of the raw materials into the crucible and refining, casting a refined solution to a surface of a water-cooled rotation roller through a tundish and forming alloy flakes, processing the alloy flakes containing at least two different compositions with hydrogen decrepitation, milling powders, magnetic field pressing, vacuum presintering, machining and sintering, and obtaining the NdFeB magnet containing cerium. The NdFeB magnet containing cerium has a density of 7.5-7.7 g/cm.sup.3 and an average particle size of 3-7 m; comprises a main phase and a grain boundary phase distributed around the main phase. A composite phase containing Tb is provided between the main phase and the grain boundary phase.

A magnetic core includes alloy phases 20 each made of Fe-based soft magnetic alloy grains including M1 (wherein M1 represents both elements of Al and Cr), Si, and R (wherein R represents at least one element selected from the group consisting of Y, Zr, Nb, La, Hf and Ta), and has a structure in which the alloy phases 20 are connected to each other through a grain boundary phase 30. In the grain boundary phase 30, an oxide region is produced. The oxide region includes Fe, M1, Si and R and further includes Al in a larger proportion by mass than the alloy phases 20.

A magnetic core has a structure in which alloy phases 20 each including Fe, Al, Cr and Si are dispersed and any adjacent two of the alloy phases 20 are connected to each other through a grain boundary phase 30. In this grain boundary phase 30, an oxide region is produced which includes Fe, Al, Cr and Si, and includes Al in a larger proportion by mass than the alloy phases 20. This magnetic core includes Al in a proportion of 3 to 10% both inclusive by mass, Cr in a proportion of 3 to 10% both inclusive by mass, and Si in a proportion more than 1% and 4% or less by mass provided that the sum of the quantities of Fe, Al, Cr and Si is regarded as being 100% by mass; and includes Fe and inevitable impurities as the balance of the core.

A grain-oriented electrical steel sheet is subjected to magnetic domain refining treatment by irradiating a steel sheet surface with an electron beam having a beam diameter d of 0.40 mm or less, wherein a modulated irradiation line region is formed with repeating units connected to each other in the line region direction, a periodic distance of the repeating units in the modulated irradiation line region is d mm to 2.5d mm, a repeating interval of the modulated irradiation line region in the rolling direction is 4.0 mm to 12.5 mm, and intensity of the electron beam is not lower than an intensity with which long and narrow divided magnetic domains extending in the modulated irradiation line region direction are formed at least on an irradiated side, and not higher than an intensity with which coating damage does not occur and a plastic strain region is not formed on the irradiated side.