TEXTURE AND PROPERTIES OF COLD-ROLLED POWDER STRIP

OF HIGHLY ALLOYED ORDERING Fe--Si AND Fe--AI ALLOYS

V. M. Beglov, A. M. Glezer, V. V. Dergach, N. M. Semenchinskii, and E. F. Sil'nikova

UDC 669.71'782:621~762

Highly alloyed Fe--Si and Fe--AI materials with extreme magnetic properties may be used in industry only if it is possible to prepare from them thin sheet and tape exhibiting high duc- tility [i]. The main efforts of research both in our country and abroad have been directed toward improving the ductility of the alloys with the aim of making it possible to roll them at normal temperature. Studies have been carried out in the direction of preparing high pur- ity materials [2, 3], use of warm rolling [2, 4-6], melting three-layer blanks [7], and pow- der metallurgy [8]. In all of these works tape after final heat treatment unavoidably became brittle, which hindered industrial use of the results obtained.

One of the factors having an effect on alloy ductility is their crystallographic texture [9, i0]. It has been demonstrated [ii] that in the plane of hot-rolled sheet the number of bends changes sharply; from ii to 1.5 for alloy With 4% Si and from 0 to 2.5 for alloy with 4.6% Si. The authors explain this by local changes in recrystallization texture.

The aim of the present work is to determine the possibility of preparing nonbrittle pow- der tape with high magnetic properties.

Studies were carried out on strips and tapes prepared from powder alloys of iron with 5- 7% Si or with 16% A1 atomized with nitrogen. Strips were cut from the tape i0 mm wide by lever or roller shears, and toroidal specimens with an outer diameter of 30 mm and inner dia- meter of 20 mm were cut out of the strip. In order to measure magnetic losses in a field of frequency 50 Hz use was made of toroidal specimens with an outer diameter of 50 mm and inner diameter of 40 mm, which were prepared in a turning machine.

Alloys were given the following heat treatment: annealing in a vacuum (5.3-9.3 mPa) at 1200°C (alloy with 5-7% Si); vacuum annealing at 1200°C, furnace cooling, followed by heating to 650°C, soaking for 0.5 h, and oil quenching (alloy with 16% AI). Magnetic properties in constant and alternating fields were measured in a torus assembled from stamped specimens or wound from tape. Magnetostriction was measured by a strain-gauge method on specimens 0.2 x i0 x i00 nun in size before and after heat treatment.

Tape ductility before and after annealing was determined from the number of bends for the tape in jaws with a radius of 5 mm. Strip texture was studied by the x ray method [12].

Magnetic properties of cold-rolled strip and tape from the test iron--silicon powder al- loys compared with the properties of industrial electrical engineering steels and also with data of Japanese researchers are given in Table i.

Magnetostriction, measured in tapes of powder alloy with 6.2% Si before annealing was (2.5-6.4).10 -6 , and after annealing %5 ~ 0. Tapes prepared from coarse (--315 + i00 ~m) pow- der particles of this alloy after annealing cannot be bent through a radius of 5 mm, and those prepared from fine (--i00 ~m) particles do not withstand more than one bend with tape 0.35 mm thick, and not more than two bends with tape 0.2 mm thick. Tape 0.2 mm thick made of irorr--aluminum powder after high-temperature annealing withstands 15 bends.

Results of texture determination for the test alloys are given in Table 2.

The magnetic properties of iron--aluminum powder are very low. For example, the maximum magnetic permeability is 8000, which is several factors worse than for cast alloys.

The magnetic properties of tape prepared from coarse powder particles of iron--silicon alloys are not surpassed by those of tape obtained from ingots, both in static and alternat- ing fields (see Table i). Powder tape remains as brittle as for cast material.

Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 3, pp. 48-50, March, 1986.

222 0026-0673/86/0304-0222512.50 © 1986 Plenum Publishing Corporation

TABLE 1

Material

Powder alloy Fe--5 %Si

! ~ T~e,,of maw

~ netic core

0,25[Laminated Wound Ditto

Powder 20 alloy 0, Fe--6,2 %Si

Laminated

Transformerl [ steel [3]: [ ] hot-rolled [0,20[ Laminated c° id'r°lledl0,201 Wound

I0,151 Ditto

Fe--5 %SI [6][ 0 30 [Laminated Fe--6,2 %Si[6][ ' {Ditto

I Powder B,o0e [ Bj.oo

fraction, mm T

-,oo...+,ooI .2,11.4o - oo..1. iooi I 44 i. o - - 1;46 1,60

~max

23 600 90

--315"ii)'+01001~'39-- ,36 t,461'50 ~0 000OO0

_ ,,2911,4 i1 ooo -- 1,601 1,70 -- 1,65"[ -- 1,82 --

1,36 '42]12500 1,30 1,35 [20 500

20 42

3O

20 16

Specific losses ton/kg

~. o

8,8 7,3

..<7,2

-<7, (J

15,4 12,3 20,4

LS...ll ,0 13,7

<~12,5

-.<~-.o

=0 o o

o

6,7 22,0 I0, I 30,5

.~<7", o <22.0

TABLE 2

Alloy

Fe--5 %Sh Coarse fraction powder

Fine fraction powder

d~formation

{111}< 112>+{001}<II0> . . (we~x~ [ 0 0 1 ) < 110>.-~[,11 I)<112 >

( weaker )

~exture

Iron + 16% aluminum T {111}<112>+{I00}<011>

annealing(1200 °C 3 h)

(1101<001>(45 %of grains)

{111}<112>+{211}< 110>+ +50,% u/o (weaker)

{III}<212>

Notation. u/o is unordered orientated phase.

Use of fine powder particles with some reduction in magnetic properties makes it pos- sible to prepare nonbrittle tape of alloy 6.2% Si having a magnetostriction close to zero. The different ductility of tape prepared from coarse and fine powder particles of iron--sili- con alloys (Table 2) may be explained by retention of strong components of rolling texture and preferential growth of grains having a crystallographic orientation {iii} <112> with the annealing conditions selected.

The fewer grains of other orientations in the structure, the higher will be annealed tape ductility.

The low magnetic properties of powder Fe--AI alloy, in spite of the markedly lower con- tent of nonmetallic inclusions than in powder Fe--Si alloy, may be explained by the high mag- netostriction of this alloy, which reinforces the negative effect of inclusions.

Conclusions

i. Cold-rolled tape 0.2 r~n thick prepared from atomized Fe--6% Si alloy powder is not surpassed in magnetic properties in static and alternating fields by tape prepared by stand- ard metallurgical technology.

2. Use of a fine atomized powder fraction makes it possible to prepare nonbrittle tape with a certain reduction in the level of magnetic properties. By changing the deformation temperature it is possible to obtain one or another texture in annealed tape.

3. Preparation of ductile tape is provided by presence within it of a sufficient quan- tity of uniformly distributed dispersed nonmetallic inclusions, which stabilize the texture of cold-rolled alloy with 6% Si.

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LITERATURE CITED

i. G. Reinbot, Magnetic Materials and Their Application [in Russian], Energiya, Leningrad (1974).

2. J. F. Nachman and W. J. Beuhler, "Iron--16% aluminum alloy cold rolled in the order-dis- order temperature range," J. Appl. Phys., 25, No. 3, 307-313 (1954).

3. E. R. Morgan and V. F. Zackey, "Plastic Fe--AI alloys," Met. Progress, No. 4, 126-128 (1955).

4. W. Pepperhoff and W. Pitch, "Eisen-Silicium-Legierungen mit h~heren Silicium-gehalten als Werkstoffe fNr die Elektrotechnik," Arch. Eisenhuttenwesen, 47, No. ii, 685-690 (1976).

5. G. Rassman and P. Klemm, "Zum Verformungverhalten von Eisen-Silicium-Legierungen mit 3 bis 6% Si," Neue Hutte, No. 7, 403-406 (1963).

6. T' Ishisaka, K. Jamabe, and T. Takahashi, "Cold rolling and magnetic properties 6.5% silicon--iron alloys," Nippon Kinzoku Gakkai shi, No. 30, 552-558 (1963).

7. N. A. Kabantsev, F. A. Radin, B. A. Karaev, et al., "Preparation and testing of electric- al engineering steel sheet with reduced magnetostriction," in: Proc. of the All-Union Meeting on Physics and Metallography of Electrical Engineering Steels and Alloys, Chere- povets (1974). T. Kimura, H. Hirabayashi, and M. Tokuyoshi, "Study of continuous rolling fabrication of iron strip from metal posders," Rev. Electrical Commun. Lab., 12, No. 3-4,215-232 (1964). R. Bozort, Ferromagnetism [in Russian], IL, Moscow (1956). V. V. Druzhinin, "Brittleness anisotropy for sheet silicon steel," Fiz. Mekh. Metalloved., ~, No. 2, 278-283 (1959). S. Bohmer and K. Gunther, "Die Spr~digkeit des Kohlenstoff~rmen siliziumlegierten Stahls," Neue Hutte, 9, No. 5, 258-294 (1964). A. K. Grigor'ev, G. V. Sokolova, E. F. Sil'nikova, et al., "Texture of magnetically soft alloys based on iron," Proc. of the 5th All-Union Meeting on Physics and Metallography of Electrical Engineering Steels and Alloys, Chelyabinsk (1978). V. V. Druzhinin, Magnetic Properties of Electrical Engineering Steel [in Russian], Ener- giya, Moscow (1974).

.

9. i0.

ii.

12.

13.

EFFECT OF HEAT TREATMENT ON THE DUCTILE PROPERTIES

OF HEAT-RESISTANT ALLOY EI698-VD IN COLD DEFORMATION

A. S. Kleshchev, N. N. Korneeva, A. A. Grebenets, and L. V. Lyakhova

UDC 621.78:669.24:539.52

In recent years cold deformation has found wide application in manufacturing components for torsion-body-type mechanical parts. However, to use this method to manufacture important parts from heat-resistant alloys is very difficult due to their low ductility at ambient tem- peratures. Neither the Soviet nor the foreign literature provides any information on the ef- fect of heat treatment on the ductility of heat-resistant nickel alloys at such temperatures.

The aim of the present authors was to study and develop a prior heat treatment for EI698- VD, which would improve its ductility characteristics at ambient temperatures, thus improving its cold deformability.

To study and develop the heat-treatment schedule, hot forged (e = 70%) rods were used. The nickel-based EI698-VD alloy had the following calculated chemical composition: 0.04% C; 0.20% Mn; 0.31% Si; 0.010% P; 0.007% S; 14.5% Cr; 0.97% Fe; 2.6% Ti; 3.0% Mo; 1.7% AI; 2.0% Nb; 0.0008% P; and 0.005% each of B and Ce. Its structure contained the strengthening y'- phase with a full dissolution temperature of I050°C. Specimens were cut out of rods and sub- jected to tempering by various schedules, above as well as below the complete y'-phase dis-

Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 3, pp. 50-52, March, 1986.

224 0026-0673/86/0304-0224512.50 © 1986 Plenum Publishing Corporation