JPH0454739B2 - - Google Patents

Description

[Detailed description of the invention]

This invention has particularly excellent toughness (fracture resistance), excellent magnetic properties and castability, and high electrical resistance, and therefore can be used to manufacture soft magnetic members by casting. Soft magnetic Fe-Si
This relates to casting alloys. Generally, the head core of a dot printer such as a word processor has a complicated shape, so a lost wax precision casting method, for example, is applied to its manufacture. Normally, the eddy current loss P that accompanies heat generation in the material is P=KB ²・f ² /〓 (where, K: shape factor, B: magnetic flux density, f: frequency, : Electrical resistance) It is proportional to the square of the frequency and inversely proportional to the electrical resistance, so it has relatively high electrical resistance and relatively good castability. Fe-Si cast alloy with higher magnetic flux density and less magnetic loss, i.e., contains 2 to 3.5% Si, with the remainder being Fe and unavoidable impurities (wt%). A soft magnetic Fe-Si casting alloy with a On the other hand, in recent years, word processors, for example, have sought to achieve even higher speeds and clearer printing.As a result, the head cores of dot printers have also become larger and more complex in shape. There is a strong desire to develop materials that have higher electrical resistance and better castability. Therefore, from the above-mentioned viewpoint, the present inventors conducted research to develop a material that has excellent magnetic properties, high electrical resistance, and excellent castability. Conventional soft magnetic Fe
-Increasing the Si content in Si casting alloys from 4 to 6.5
%, the castability is improved without sacrificing the excellent magnetic properties, and the electrical resistance is further increased.
At ~6.5%, on the other hand, toughness (fracture resistance) decreases,
Cracks and chips are likely to occur in castings when breaking the casting mold, cutting sprues, runners, risers, etc., and during finishing processing, but Mn, W, Mo,
When one or more of Cr, Tc, and Re are contained, the magnetic properties are not impaired and the toughness (fracture resistance) is significantly improved, eliminating the above problems. ,moreover
They found that containing Al further increases the electrical resistance. This invention was made based on the above knowledge, and includes Si: 4 to 6.5%, one of Mn, W, Mo, Cr, Tc, and Re.
Species or two or more species: 0.3 to 1.5%, and if necessary, Al: 0.1 to 2%, with the remainder being Fe and inevitable impurities, and has a composition with particularly high toughness and electrical properties. has resistance,
Furthermore, it has excellent castability and magnetic properties, making it suitable for use in manufacturing soft magnetic parts that require high frequency properties, such as dot printer head cores, by casting. It is. Next, the reason why the composition of the cast alloy of the present invention is limited as described above will be explained. (a) Si The Si component has the effect of securing the necessary magnetic properties and significantly increasing the electrical resistance and castability, but if its content is less than 4%, the desired high electrical resistance and castability are ensured. On the other hand, if the content exceeds 6.5%, embrittlement tendency will appear, so the content should be reduced to 4%.
It was set at ~6.5%. (b) Mn, W, Mo, Cr, Tc, and Re These components have the effect of forming a solid solution in the base material and significantly improving the toughness (fracture resistance) of the alloy, but their content is 0.3 If the content is less than 1.5%, the desired effect of improving toughness cannot be obtained, while if the content exceeds 1.5%, not only the desired effect of improving toughness cannot be obtained, but also the magnetic properties will deteriorate. was set at 0.3% to 1.5%. (c) Al Since the Al component has the effect of further improving electrical resistance, it is included as necessary when particularly high electrical resistance is required, but if the content is less than 0.1%, the desired The content was set at 0.1 to 2% because no improvement effect could be obtained and, on the other hand, if the content exceeded 2%, a tendency towards embrittlement would appear. In this case, Si and
Since embrittlement occurs even if the total amount of Al exceeds 6.5%, Si+Al must be kept at 6.5% or less. Furthermore, the cast alloy of this invention can be melted and melted in the atmosphere.
When cast, Mn, W, Mo, Cr, Tc, and Re
Melting and casting in vacuum or in an Ar atmosphere is desirable because alloying elements such as oxidize and exist in the form of oxides in the alloy, making it impossible to obtain the desired toughness improvement effect. Next, the casting alloy of the present invention will be specifically explained using examples. Example Casting alloys 1 to 20 of the present invention and conventional casting alloys having the respective compositions shown in Table 1 were melted in an ordinary high-frequency melting furnace in an Ar atmosphere, and then centrifugally cast with a diameter: It was cast into a chip with dimensions of 33mmφ x thickness: 6mm. Next, from this chip, a ring-shaped specimen with dimensions of outer diameter: 32 mmφ x inner diameter: 22 mmφ x thickness: 5 mm for measuring magnetic properties, and a ring-shaped specimen with dimensions of diameter: 10 mmφ x thickness: 3 mm for crack occurrence measurement were made. A circular specimen was cut out. Using these specimens, magnetic properties, electrical resistance, and the presence or absence of cracking were measured. The magnetic properties were determined by applying 60 turns of the primary coil and 20 turns of the secondary coil to the specimen, creating a hysteresis loop using the normal varistake method, and calculating the coercive force from this.

【table】

[Table] (Hc), maximum magnetic permeability (μm), and maximum magnetic flux density (Bm) were determined. The maximum magnetic field in this case was set to 10 oersteds. Further, the electrical resistance was measured by a four-probe method using the above-mentioned ring-shaped specimen and circular specimen. in this case,
Although there was almost no difference in the measured values between the two specimens,
The average value was calculated. Furthermore, the presence or absence of cracking was determined by observing the situation after pressing the center of the specimen with a load of 750 kg using a Brinell hardness measuring tester. These results are shown in Table 1. As shown in Table 1, the cast alloys 1 to 1 of the present invention
It is clear that all Nos. 20 and 20 have magnetic properties and high toughness required for high-frequency soft magnetic members equivalent to conventional cast alloys, and have even higher electrical resistance than conventional cast alloys. In addition, head cores for dot printers were manufactured using the cast alloys 2 and 14 of the present invention by the lost wax precision casting method, and the castability was extremely good, and no cracks were observed during subsequent cutting operations, making them sound and sound. A good casting was obtained. As mentioned above, the casting alloy of the present invention has excellent magnetic properties, extremely high electrical resistance, and excellent toughness and castability, so it can be used in large and complex shaped head cores of dot printers, for example. It is suitable for manufacturing soft magnetic members such as by casting without cracking or chipping, and the soft magnetic members produced by this method generate very little heat even when used at high speeds.
Since the cast alloy of this invention has the above characteristics,
It has industrially useful properties such that it can be used not only for the head core of dot printers, but also for the manufacture of plunger yoke materials for dot printers, and stators and rotors for stepping motors.

Claims (1)

[Claims] 1 Si: 4 to 6.5%, one of Mn, W, Mo, Cr, Tc, and Re
Species or two or more species: 0.3 to 1.5%, with the remainder consisting of Fe and unavoidable impurities (weight%). Excellent toughness, magnetic properties, castability, and high electrical Soft magnetic Fe-Si cast alloy with resistance. 2 Si: 4 to 6.5%, one of Mn, W, Mo, Cr, Tc, and Re
Toughness characterized by having a composition (by weight % or more) containing a species or two or more species: 0.3 to 1.5%, further containing Al: 0.1 to 2%, and the remainder consisting of Fe and unavoidable impurities, A soft magnetic Fe-Si cast alloy with excellent magnetic properties and castability, and high electrical resistance.