Method of the thermal treatment of the hard magnetic alloys on the basis of iron

FIELD: metallurgy; instrumentation technologies; relay engineering; electric machine industry; medicine; other industries; methods of production of the hard magnetic alloys.

SUBSTANCE: the invention is pertaining to metallurgy, in particular, to production of the hard magnetic alloys made on the basis of Fe-Cr-Co system, which are used in auto-instrumentation technologies, relay engineering, electric machine industry, medicine, etc. For increasing the magnetic properties of the treated permanent magnets by 3-5 % as well as the product yield the magnet made out of the alloy 25X15КА is exposed to the homogenization, hardening, thermomagnetic (thermal) treatment, multi-stage tempering and the thermal-cycle treatment in the final stage of the temperature interval of 510-470°С in the amount of 3-5 cycles at the final stage of the tempering.

EFFECT: the invention ensures the increased magnetic properties of the treated permanent magnets by several percents.

1 ex, 6 dwg, 6 tbl

 

The invention relates to metallurgy, in particular to the production of hard magnetic alloys based on Fe-Cr-Co, which are used in aviapriborostroeniya, relay engineering, electrical engineering, medicine, etc..

Hard magnetic alloys of the system Fe-Cr-Co have many advantages over other hard magnetic alloys: respond to all types of plastic and blade processing (rolling, drawing, pressing, turning, milling, stamping, etc. and possess high strength (up to 1000 MPa), high temperature and temporal stability (TCI=0,022%/°). One disadvantage of these alloys is the long duration of heat treatment (˜24 hours). This disadvantage is due to the relatively low temperature range (650-500° (C) the high temperature α solid solution of a mixture of two phases: α1phase enriched in iron and cobalt, and α2-a phase enriched with chromium, in the process of forming vysokokoertsitivnye state.

It is known that the standard heat treatment FeCrCo alloys consists of homogenization at 1150-1300°, hardening α solid solution, isothermal thermomagnetic treatment at 630-660° (in the case of obtaining magnetotherapy magnets used isothermal heat treatment) and stepped vacation in tempera is to become the interval 620-520° With a consistent decrease in the temperature of vacation each level 20-30°C. Tempering at 500°during the day doesn't increase the magnetic properties (GOST 24897-81, U.S. patent No. 4194932, MKI H01F 1/04; NCI 148/108, 148/31 .57; Appl. 7.02.78,, publ. 25.03.80,) prototype.

A known method of thermal processing of hard magnetic alloys based on iron, including homogenization, tempering, isothermal processing and dispensing with thermal Cycling up to 620-625°and cooling to 550°With the number of cycles 4-5 (SU 985071 A, C21D 1/04, 30.12.1982, 4c.).

The invention is aimed at reducing the duration of the heat treatment, and to increase the yield of products by applying cyclic heat treatment on the final stages of the vacation, which increases the magnetic properties of the processed magnets (3-5%) and increases the yield of products.

The invention consists in that the heat treatment of hard magnetic alloys based on iron (in particular, on the basis of Fe-Cr-Co), including homogenization, tempering, isothermal thermomagnetic processing and multi vacation, according to the proposal in the final stage carry out thermal Cycling in the range 510-470°With the number of cycles 3-5.

Example. Permanent magnets in the amount of 164 pieces of alloy HE were processing what s in standard mode, including homogenization at 1200°C for one hour and quenched in water from this temperature. Then, the permanent magnets were subjected to isothermal thermomagnetic treatment at 640°C for 1 h followed step by leave: 620°C(1 h)+600°C(1 h)+580° (2 h)+560°With(3 h)+520° (4 h)+500° (10 h).

Figure 1 shows the distribution of the magnets on the coercive force after the standard heat treatment, with the flow f=27-29,5 mkvb (i.e. rejected on the stream).

Figure 2 shows the distribution of the magnets on the coercive force after the standard heat treatment, with the flow f=30-32 mkvb (i.e. fit on the stream).

Figure 3 shows the distribution of the magnets on the coercive force after conducting additional leave under 480°C for 24 h with flow f=27-29,5 mkvb.

Figure 4 shows the distribution of the magnets on the coercive force after conducting additional leave under 480°C for 24 h with flow f=30-32 mkvb.

Figure 5 shows the distribution of the magnets on the coercive force after additional thermocyclic treatment in the interval 510-470° (for ˜5 h in the number of 3-cycles), with flow f=27-29,5 mkvb.

Figure 6 shows the distribution of the magnets on the coercive force after additional thermal Cycling clicks the processing in the interval 510-470° (During ˜5 h in the number of 3-cycles), with flow f=30-32 mkvb.

Magnets made of an alloy HK (GOST 24897-81) in the amount of 164 pieces that THAT should be the thread ≥30 mkvb and the coercive force Hcm≥40 kA/m, after thermal treatment in the container by heat treatment, ending with a vacation at 500° (20 hours), gave the following results: 119 magnets were fit as to the thread, and the coercive force. 45 rejected magnets 31 and the magnet didn't comply with the coercive force and 43 of the magnet did not correspond to the flow (see figure 1 and 2).

The thread f=27-29,5 mkvb (table 1).

N=43 pcs. Average =39,4 kA/m; minutes=35,1; max=42,8; dispersion =3,29; STD. deviation=1,81; STD. error of the mean =0,3.

Table 1
The interval HcmNumberTotal Qty% of total countTotal %
34,000<x<=35,000000,00000,0000
35,000<x<=36,000224,65124,6512
36,000<x<=37,000356,976711,6279
37,000<x<=38,000499,302320,9302
38,000<x<=39,00081718,604739,5349
39,000<x<=40,00092620,930260,4651
40,000<x<=41,00073316,279176,7442
41,000<x<=42,00094220,930297,6744
42,000<x<=43,0001432,3256of 100.0000

The thread f=30 -32 mkvb (table 2).

N=121 units Average=42,9 kA/m; minutes=39,2; max=45,7 kA/m; dispersion=1,758; the mill. deviation=1,32; standard. error of the mean=0,12; =-0,14.

Table 2
The interval HcmNumberTotal Qty% of total countTotal %
38,000<x<=39,000000,00000,0000
39,000<x<=40,000221,65191,6529
40,000<x<=41,0008106,61168,2645
41,000<x<=42,000223218,181826,4463
42,000<x<=43,000 356728,925655,3719
43,000<x<=44,000289523,140578,5124
44,000<x<=45,0001911415,702594,2149
45,000<x<=46,00071215,7851of 100.0000

More holiday magnets in 480°C for 24 h practically does not change their magnetic properties (Fig 3 and 4).

The thread f=27-29,5 mkvb (table 3).

N=43 pcs. Average=39,4 kA/m; minutes=35,1; max=42,8; dispersion =3,31; STD. Deviation=1,82; STD. error of the mean=0,3; asymm.=-0,47; kurtosis=-0,22.

Table 3
The interval HcmNumberTotal Qty% of total countTotal %
35,000<x<=36,000224,65124,6512
36,000<x<=37,000356,976711,6279
37,000<x<=38,000499,302320,9302
38,000<x<=39,00081718,604739,5349
39,000<x<=40,000 72416,279155,8140
40,000<x<=41,00093320,930276,7442
41,000<x<=42,00094220,930297,6744
42,000<x<=43,0001432,3256of 100.0000

All 43 of the magnet still did not meet THE largest stream.

The thread f=30-32 mkvb (table 4).

N=121 units Average=42,9 kA/m; minutes=40,5; max=45,7 kA/m; dispersion=1,57; the mill. deviation=1,255; standard. error of the mean=0,11; asymm.=0,10: kurtosis=-0.74.

Table 4
The interval HcmNumberTotal Qty% of total countTotal %
39,000<x<=40,000000,00000,0000
40,000<x<=41,000775,78515,7851
41,000<x<=42,000253220,661226,4463
42,000<x<=43,000356728,925655,3719
43,000<x<=44,000289523,1405 78,5124
44,000<x<=45,0001911415,702594,2149
45,000<x<=46,00071215,7851of 100.0000

However, the application of cyclic heat treatment in the range 510-470°With (cycle: 510°With cooling for 40 min to 470° + heating up to 510°C for 40 min) in an amount of 3 cycles gave a significant improvement of the magnetic properties, especially for magnets with low flow (figure 5)

The thread f=27-29,5 mkvb (table 5).

N=43 pcs. Average=39,9 kA/m; minutes=37,1; max=42,6; dispersion=2,435; STD. the discard.=1,56; STD. error of the mean=0,24; asymm.=0,08; kurtosis=-1,05.

Table 5
The interval HcmNumberTotal Qty% of total countTotal %
36,000<x<=37,000000,00000,0000
37,000<x<=38,0005511,627911,6279
38,000<x<=39,000101523,255834,8837
39,000<x<=40,00072216,279151,1628
40,000<x<=41,000 123427,907079,0698
41,000<x<=42,0003376,976786,0465
42,000<x<=43,00064313,9535of 100.0000

The thread f=30 -32 mkvb (table 6).

N=121 units Average=43,2 kA/m; minutes=40,5; max=46, 6 kA/m; dispersion=1,74; the mill. deviation=1,32; standard. error of the mean=0,12; asymm.=-0,045; kurtosis=-0

Table 6
The interval HcmNumberTotal Qty% of total countTotal %
39,000<x<=40,000000,00000,0000
40,000<x<=41,000775,78515,7851
41,000<x<=42,000182514,876020,6612
42,000<x<=43,000285323,140543,8017
43,000<x<=44,000328526,446370,2479
44,000<x<=45,0002811323,140593,3884
45,000<x<=46,0006 4,958798,3471
46,000<x<=47,00021211,6529of 100.0000

43 magnets 21, the magnet was suitable as a flux and coercive force (i.e. almost 50% of the rejected magnets managed to bring up required on THE parameters).

Similar cyclic heat treatment 121 of the magnet (which have been suitable for flow) in the temperature interval 510-470°leads to a noticeable increase of the coercive force (up to 46.5 kA/m).

The method of thermal processing of hard magnetic alloys based on iron, including homogenization, tempering, isothermal thermomagnetic processing and multi vacation, characterized in that at the final stage of vacation spend thermal Cycling in the temperature range 510-470°With number of cycles 3-5.



 

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