JPS6312936B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a Fe-Cr-Co magnetic material. Magnetic materials suitable for use in relays, signal generators and electro-acoustic transducers such as loudspeakers and telephone handsets are those which exhibit particularly high coercivity, remanence and energy product values. Cobalt Co is an expensive substance. therefore expensive
It has high magnetic properties and formability (fine grain structure) comparable to that of Co-based Fe-Cr-Co alloys.
It has been desired to develop a Fe-Cr-Co alloy containing Co. However, conventional low Co content alloys have always contained at least one fourth component, sometimes in relatively high amounts. Such additives have been used for a variety of reasons, such as lowering the solution treatment temperature, but on the other hand they can degrade the magnetic properties of the alloy or reduce its workability and therefore have to be compensated for. In order to achieve this, various complicated measures were required for heating, heat and/or cold working, aging treatment, etc. Some of the predetermined alloys with suitable magnetic properties include
There are Al-Ni-Co-Fe and Cu-Ni-Fe alloys.
These are among a group of alloys that are thought to undergo spinodal decomposition resulting in a fine two-phase microscopic structure. Recently, alloys containing Fe, Cr and Co have been investigated for their suitability in the production of permanent magnets. Specifically, a certain ternary Fe−Cr−
Co alloys are disclosed in H. Kaneko et al., "New Fe-Cr-Co Ductile Permanent Magnets," AIP Conference Proceedings No. 5, 1972, p. 1088, and U.S. Pat. No. 3,806,336, "Magnetic Alloys." ing.
Quaternary alloys containing ferrite-forming elements such as Ti, Al, Si, Nb or Ta in addition to Fe, Cr and Co are disclosed in US Pat. "Type Magnetic Alloy", U.S. Patent No. 3989556 "Semi-Hard Magnetic Alloy and Method for Producing the Same", U.S. Patent No. 3982972 "Semi-hard Magnetic Alloy and Method for Producing the Same" and U.S. Patent No. 4075437 "Composition and Processing Including Magnetic Alloy" and equipment”. In quaternary alloys, for example, Ti, Al, Si, Nb,
Alternatively, the use of ferrite-forming elements such as Ta may facilitate the formation of an alpha phase structure of preliminary grain refinement by low-temperature slow cooling, especially in the presence of high Co contents or impurities such as C, N or O. It is said. The present invention provides: (a) low-containing products containing no additives other than the incidental presence of very small amounts of unintended impurities (undesirables);
Co-component Fe-Cr-Co alloy, (b) having high magnetic properties comparable to those obtained with high Co content, and (c) having a significant reduction in cross-sectional area and/or at least 30° in the direction. The present invention provides those skilled in the art with a method for producing an alloy having a fine grained structure that provides bendable cold workability. The present invention is a substantially ternary Fe-Cr-Co magnetic alloy whose grain size is sufficiently fine to yield at least 3000 grains/mm ³ and whose coercivity is 300
-600 Oersted, residual magnetism 8000-13000 Gauss, and maximum magnetic energy product 1-6 MG0e. The alloy consists essentially of 25-29 weight percent Cr, 7-12 weight percent Co and the balance
expediently by a process comprising solution annealing at a temperature of 650-1000°C to form a fine-grained, substantially single-phase alpha structure, followed by cold forming and aging. It is possible to manufacture Magnets made from such alloys can be used, for example, in electro-acoustic transducers, such as loudspeakers and telephone handsets, relays and signal devices. According to the invention, it contains preferably 25-29 weight percent Cr, preferably 7-12 weight percent Co and the balance substantially Fe.
It is possible to make Fe-Cr-Co alloys having at the same time a maximum energy product of 1-6 MG0e and a grain size corresponding to at least 3000 grains/ ^mm3 . It should be noted that such a grain structure is particularly beneficial when the alloy is cold formed. A narrower range of Cr content may be preferred and an upper limit of 28 weight percent Cr is preferred, particularly with respect to optimizing the alloy's formability and a lower limit of 26 weight percent Cr with regard to optimizing magnetic properties. It will be done. The alloy of the present invention may contain, for example, constituent elements Fe, Cr and Co.
or their alloys in a crucible or furnace, such as an induction furnace. On the other hand, metal bodies having a composition within a certain range can be produced by powder metallurgy. In the production of alloys, particularly by casting from a melt, care must be taken to avoid the inclusion of excessive amounts of impurities originating from the raw materials, the furnace, or the atmosphere above the melt. If such care is taken, the addition of ferrite-forming elements can be omitted, especially if sufficient care is taken to minimize the presence of impurities such as nitrogen. It is desirable to provide slag protection to the melt in vacuum or in an inert atmosphere, such as an argon atmosphere, to minimize oxidation and excess nitrogen contamination. The amount of inherent impurities is preferably C0.05 weight percent,
N0.05 weight percent, Si0.2 weight percent,
Mg0.5 weight percent, Ti0.1 weight percent,
Ca0.5 weight percent, Al0.1 weight percent,
Mn0.5 weight percent, S0.05 weight percent,
O (oxygen) is maintained below 0.05 weight percent. Typical processing after casting is as follows. The alloy is placed at a temperature at which it is in the two-phase alpha+gamma state for 1-10 hours; temperatures of 1100-1300 degrees are generally suitable for this purpose. 9 each
Weight percent Co and 11 weight percent Co
More specific preferred limits for such temperatures corresponding to alloys containing . The alloy is then hot worked in such a two-phase state by hot rolling, casting or extrusion to destroy the as-cast structure, and if desired the alloy can be formed by cold working. It is possible. In order to develop a uniform fine grain structure, the alloy is then solution annealed so that it is in a substantially single phase alpha state and at a temperature generally between 650 and 1000C. The preferred upper limit for the annealing temperature for a particular alloy is the following value: 25% by weight
950°C for alloys containing Cr and 7% by weight Co; 875°C for alloys containing 25% by weight Cr and 12% by weight Co
°C, 1100 °C for alloys containing 29 weight percent Cr and 7 weight percent Co, and
29 wt% Cr and 12 wt%
975° C. for Co-containing alloys, which can be conveniently obtained by approximately linear interpolation between 975° C. and even above 1000° C. is not necessary to minimize grain growth. In connection with improved kinetics, a lower limit of 800°C is preferred, and in connection with minimizing the gamma phase, a preferred upper limit is approximately linear between the respective values 925°C, 850°C, 1075°C and 950°C. is obtained by interpolation of and also under the above assumption that the annealing temperature does not exceed 1000°C. If the alloy is cold worked, the solution treatment to substantially recrystallize and homogenize the alloy may take between 10 and 2 minutes depending on the annealing temperature and ingot size.
Can be adopted from time to time. More typically the time required is 30-90 minutes. Solution treatment can be carried out in air or with oxygen removed to minimize surface oxidation. Solution treatment can be carried out, for example, by water or brine quenching or, in the case of thin strips, by air quenching. Preferably, the cooling rate through the alloy is at least
It is terminated by rapid cooling in such a way as to bring about 1000° C./min. In this respect, the alloy is at or near room temperature, ie at a temperature not exceeding 100° C., and has a substantially uniform fine grain size not exceeding 70 microns (corresponding to at least 3000 grains/mm ³ ). The average particle size of 70 microns is the limit at which the alloy can be cold worked without easily cracking or crumbling.
Such a grain structure is shown in FIG. 2 and can be contrasted with the coarse structure obtained by slow cooling at high temperatures as shown in FIG. At temperatures not exceeding 100° C., the alloy can then be cold-formed, for example by bending, drawing, deep drawing or mold bending. Particular benefits derive from this fine-grained structure when the alloy is cold-formed by wire drawing, deep drawing or bending, ie by methods that produce at least local tension deformations. For uniform fine-grained structures of slow-cooled and quenched alloys, reduction is possible to an amount corresponding to a substantial cross-sectional area reduction of at least 50 percent. Similarly, bending can result in a change in direction of at least 30°, and this resulting radius of curvature is such that it does not exceed a value proportional to the change in direction, and this For a change in direction, it is equal to the thickness of the part to be bent, and for a change in direction of 90°, it is equal to four times the thickness of the part to be bent. The treatment as described above particularly comprises the step of maintaining the alloy at a temperature corresponding to an essentially single-phase alpha state. Alternative treatments characterized in this way can consist, for example, by essentially single-phase hot working, cooling and forming with finishing temperatures in the alpha range. Furthermore, shaping can be carried out in stages with intermediate additional solution treatment and quenching. Additional processing steps, such as machining, for example by drilling, lathing or milling, before and after forming are not disturbed. The formed alloy is finally subjected to an aging treatment to develop magnetic hardening. Such aging can follow any of a variety of schemes, such as those disclosed in U.S. Pat. Oersted, giving rise to the production of magnets with a magnetic energy product of 1,000,000-6,000,000 Gauss-Eersted. Such alloys can therefore function as magnets in electro-acoustic transducers such as relays, signal and loudspeaker and telephone handsets, with respect to magnetization in a magnetic field. In the following examples, the metal phase structure and grain size were determined by X-ray diffraction analysis, hardness measurements, and metallurgical microscopic analysis of the microstructure after solution treatment and quenching, but before cold forming. The average particle size was 25-40 microns as shown in the table. Table 1 also shows the residual magnetism Br, coercive force Hc, and energy product (BH) max determined after the aging treatment of the alloy. Example 1 An alloy ingot containing 26.8 weight percent Cr, 9.4 weight percent Co, and the balance substantially Fe was cast from a melt. Ingot dimensions are 1.25 inches (31.8 mm) thick and 5 inches (127 mm) wide.
mm) and 12 inches (304.8 mm) long. This cast ingot was heated to a temperature of 1250°C and 1/4 inch (6.4
mm) and water-cooled. Cut a piece of this board 0.1 inch (2.5 mm) thick and wide at room temperature.
Cold worked into strips having a diameter of 0.625 inches (15.9 mm). The strip was annealed at 900°C for 30 minutes and water cooled. this strip
reheating to 630°C, holding at this temperature for 1 hour and cooling at a substantially constant rate of 15°C/h to a temperature of 555°C;
Hold at 540°C for 3 hours and at 525°C for 4 hours. Example 2 A strip of alloy containing 27.7 weight percent Cr, 10.9 weight percent Co and the balance substantially Fe was cast as described in Example 1.
It was made by hot working, quenching, solution treatment, cooling and rolling. Reheat this strip to 635°C and
Hold at this temperature for 3 minutes, at a virtually constant rate of 15
Cooled to 555° C./h, held at 540° C. for 3 hours and held at 525° C. for 4 hours. Example 3 A strip of alloy containing 27.3 weight percent Cr, 7.2 weight percent Co, and the balance substantially Fe was prepared as described in Example 1. The strip was reheated to 620°C and held at this temperature for 1 hour, at a virtually constant rate of 15°C/k.
Cool to 555℃, 2 hours at 555℃, 3 hours at 540℃,
It was held at 525°C for 16 hours. Example 4 A strip of alloy containing 26.8 weight percent Cr, 10.6 weight percent Co, and the balance substantially Fe was prepared as described in Example 1. The strip is soft and ductile and can be easily bent in each direction up to 90° at an acute end with a radius of curvature of 1/32 inch (0.08 mm) or stretched to provide a 99 percent area reduction. I was able to do that. Each strip has an alloy temperature
Hold at 680℃ for 30 minutes and then rapidly at the first speed of 140℃/h.
It was aged by cooling to 615°C and then cooling to a temperature of 525°C with an exponential reduction rate of 20-2°C/h. Example 5 A 0.7 inch (17.8 mm) diameter rod of an alloy containing 27.9 weight percent Cr, 10.7 weight percent Co, and the balance Fe was made by casting, hot working, solution treating, and quenching. . This rod was cold drawn into a 0.07 inch (1.78 mm) diameter wire (with a 99 percent reduced cross-sectional area) and
Solution treatment was carried out for a minute and cooled to room temperature. This drawn wire was held at 700°C for 30 minutes and then 615°C at a speed of 30°C/h in a magnetic field of 1000 Oersted.
The aging heat treatment was carried out by cooling to a temperature of 480°C with an exponential decreasing rate of 20-2°C/h.

[Table] Example 6 Contains the following components: Fe-28Cr-15Co-1Al-0.25Zr
Five ingots weighing 318Kg (700 pounds) were cast.
Hot rolled, cold rolled into a 2.54 mm (0.1 inch) thick strip, solution treated for 30 minutes at a temperature of approximately 950°C, water cooled, and then heated to a temperature of 670°C to 610°C at 200°C/hour. Aging treatment is performed by continuously cooling at a rapid rate to obtain appropriate magnetism, and then at a rate of 15℃/hour.
It was continuously cooled to 525°C and maintained at 525°C for 3 hours. Next, five ingots of the same size made of the ternary alloy of the present invention of Fe-28Cr-10.5Co were cast, and after hot rolling, cold rolling, solution treatment, and water cooling under the above conditions.
Continuously cooled from 670℃ to 615℃ at a rate of 100℃/hour, further cooled continuously at a rate of 15℃/hour to 570℃, and finally at a rate of 7.5℃/hour. Sade
It was continuously cooled to 510°C. The mechanical properties (hardness) and strip workability of two types of ingots were tested in the solution treatment state, and after the heat treatment was completed, the residual magnetism Br and coercive force Hc were tested.
and energy product (BH)max were measured. The results are shown in Tables 1 and 2. The formability shown in Tables 1 and 2 shows the results of crack occurrence when six strip test pieces were bent on a mandrel with a radius of curvature approximately 1/2 of the strip thickness. This is the total score for six samples of the scoring results. That is, no cracks at all...3 points Hairline cracks...2 points Significant cracks...1 point Therefore, what is shown as 18 is the highest score for bending.

【table】

[Table] Example 7 A ternary alloy made of Fe-27Cr-9Co produced by the method of the present invention was mixed with a conventionally known Fe-27Cr-9Co-
A comparison with 1Si and Fe-27Cr-9Co-1Ti is shown below. Samples were solution treated at 930°C for 30 min.
After water cooling, aging treatment for isotropic magnetic properties and anisotropic magnetic properties was performed. Samples with isotropic magnetic properties were cooled from 670°C to 610°C at a rate of 60°C/hour, held at a temperature of 615°C for 30 minutes, and then cooled to 570°C at a rate of 15°C/hour.
and finally at a rate of 4℃/hour.
It was made by aging treatment consisting of cooling to 510℃. 650 samples with similarly anisotropic magnetic properties
7°C to 540°C in a magnetic field of 900 oersteds.
It was produced by an aging treatment consisting of cooling at a rate of 4°C/hour to 510°C, and then removing the magnetic field and cooling at a rate of 4°C/hour. The residual magnetism Br in each case,
Coercive force Hc and energy product (BH) max are shown in Tables 1 and 2.

【table】

【table】 [Brief explanation of the drawing]

FIG. 1 shows phase diagrams of two Co-containing Fe-Cr-Co alloys. Figure 2 shows two types of Co-containing
This is a 100x micrograph of a Fe-Cr-Co magnetic alloy. Figure 3 shows two types of Fe-Cr-Co containing Co.
100x micrograph of different treatments of magnetic alloys.

Claims (1)

[Claims] 1. Fe containing 25-29% by weight of Cr, 7-12% by weight of Co and the balance Fe other than small amounts of incidental impurities.
A method for manufacturing a magnetic article made of a Cr-Co magnetic alloy, the method comprising processing the Fe-Cr-Co alloy through steps including heat treatment and aging of the alloy, comprising: subjected to an annealing temperature selected to provide an average particle size in the alloy of
and where the annealing temperature does not exceed 1000°C, and (a) 650 to 950°C if said alloy contains 25% Cr and 7% Co by weight; (b) said alloy contains 25% by weight 650-875°C when said alloy contains 29 wt% Cr and 12 wt% Co;
650-1100℃ with Cr and 7 wt% Co, (d)
The alloy contains 29 wt% Cr and 12 wt% Co
(e) its limits are the range obtained by approximate linear interpolation at intermediate levels of Cr and Co; (2) 100°C to the desired shape; formed by wire drawing or deep drawing in an amount corresponding to a reduction in cross-sectional area of at least 50% at a temperature not exceeding The resulting radius of curvature should not exceed a value proportional to the change in direction, a value equal to the thickness of the bent part for a change in direction of 30°, and a value proportional to the thickness of the bent part for a change in direction of 90°. and (3) aging the alloy. 2. In the method according to claim 1, the annealing temperature is preferably 800 to 925°C and 800 to 925°C for each of the alloy compositions (a), (b), (c), and (d), respectively.
The above method, characterized in that the temperature is 850°C, 800-1075°C and 800-950°C. 3. In the method according to claim 1 or 2, step (1) is performed by at least the following method, namely (a) solution treatment, or (b) hot working that ends at the solution treatment temperature. The above method, characterized in that it is carried out in one go. 4. In the method of claim 1, 2 or 3, the alloy is subjected to at least the following process before step (1): (a) the alloy is heated at a temperature of 1100 to 1300°C; immersion treatment; or (b) additional hot working of the alloy at a temperature of 1100 to 1300°C after said immersion treatment; or (c) one of the additional cold working of the object after said hot working. Said method, characterized in that it additionally processes. 5. A method according to claim 1, 2, 3 or 4, characterized in that the shaping is carried out in a step with an additional intermediate solution treatment and quenching. . 6. The method of any one of claims 1 to 5, wherein the aging treatment comprises: (a) cooling at an essentially constant rate; or (b) cooling at a first high average rate. A method as described above, characterized in that it is carried out by subsequently cooling at a second slow average. 7. The method according to any one of claims 1 to 6, characterized in that the aging treatment is carried out in the presence of a magnetic field. 8. In the method of any of claims 1 to 7, the object is additionally treated (a) after step (1) and before step (2), and/or (b) after step (2). Said method, characterized in that machining is carried out after step 2) and before step (3). 9. In the method of any of claims 1 to 8, incidental impurities are contained in at least the following amounts: 0.05% by weight C, 0.05% by weight N, 0.2% by weight Si, 0.5% by weight %Mg, 0.1% by weight
of Ti, 0.5% by weight of Ca, 0.1% by weight of Al, 0.5% by weight of Mn, 0.05% by weight of S, and 0.05% by weight of O.