EP0792943A1 - Iron-nickel alloy and cold-rolled strip with cubic texture - Google Patents

Abstract

Iron-nickel alloy has the composition (by wt.): 30-85%Ni + Co, 0-10% Co + Cu + Mn, 0-4% Mo + W + Cr, 0-2% V + Si, 0-1% Nb + Ta, 0.003-0.05% C, 0.003-0.15% Ti, 0.003-0.15% Ti + Zr + Hf, 0.001-0.015% (exclusive) S + Se + Te, 0-1% Nb + Ta + Ti + Al, balance Fe and impurities. Also claimed are: (i) a method of producing a cubic textured cold rolled strip of the above alloy; and (ii) a method of producing a toric magnetic core of the above alloy. Also claimed are: (i) a cold rolled strip of the above iron-nickel alloy, having a cubic recrystallisation texture of (100)(001) type; (ii) use of this strip for making a shadow mask for a CRT; and (iii) a toric magnetic core of the above alloy having a cubic texture. Preferably, the alloy contains 0.005-0.05% Ti, 0.001-0.025% Hf + Zr, 0.002-0.007% S, 0.005-0.02% C, 0.05-1% Mn and ≤ 0.05% Nb + Ta. The impurities preferably comprise less than 0.001% Mg, less than 0.0025% Ca, less than 0.05% Al, 0.0025% O, less than 0.005% N, less than 0.01% P and less than 0.01% total of Sc, Y, La, Ce, Pr, Nd and Sm.

Description

The present invention relates to an iron-nickel alloy.

Iron-nickel alloys, the chemical composition of which comprises, by weight, from 27% to 60% of nickel, from 0% to 7% of cobalt, the rest being iron and impurities resulting from the production, are used in the form cold-rolled and annealed strips, in particular for manufacturing soft magnetic cores. Annealing, carried out on very cold-worked cold-rolled strips, has the advantage of giving these alloys a cubic recrystallization texture whose magnetic properties are very favorable for certain applications such as wound cores for magnetic amplifiers. In particular, the iron-nickel alloy strips with a cubic texture have a very rectangular hysteresis cycle (Br / Bs> 95%). However, these alloys have the disadvantage of being difficult to manufacture. The annealing temperature range favorable to obtaining a good texture and satisfactory magnetic properties is too narrow, less than 25 ° C., for manufacturing to be reliable, in particular because the position of this temperature range depends poorly known parameters.

The object of the present invention is to remedy this drawback by proposing an iron-nickel alloy which is easier to manufacture than the alloy according to the prior art.

$$\text{0\% ≤ Co + Cu + Mn ≤ 10\%}$$

$$\text{0\% ≤ Mo + W + Cr ≤ 4\%}$$

$$\text{0\% ≤ V + Si ≤ 2\%}$$

$$\text{0\% ≤ Nb + Ta ≤ 1\%}$$

$$\text{0,003\% ≤ C ≤ 0,05\%}$$

$$\text{0,003\% ≤ Ti ≤ 0,15\%}$$

$$\text{0,003\% ≤ Ti + Zr + Hf ≤ 0,15\%}$$

$$\text{0,001\% ≤ S + Se + Te ≤ 0,015\%}$$

le reste étant du fer et des impuretés résultant de l'élaboration, la composition chimique satisfaisant, en outre, la relation: $$\text{0\% ≤ Nb + Ta + Ti + Al ≤ 1\%}$$

To this end, the subject of the invention is an iron-nickel alloy, the chemical composition of which comprises, by weight: $$\text{30\% ≤ Ni + Co ≤ 85\%}$$

$$\text{0\% ≤ Co + Cu + Mn ≤ 10\%}$$

$$\text{0\% ≤ Mo + W + Cr ≤ 4\%}$$

$$\text{0\% ≤ V + If ≤ 2\%}$$

$$\text{0\% ≤ Nb + Ta ≤ 1\%}$$

$$\text{0.003\% ≤ C ≤ 0.05\%}$$

$$\text{0.003\% ≤ Ti ≤ 0.15\%}$$

$$\text{0.003\% ≤ Ti + Zr + Hf ≤ 0.15\%}$$

$$\text{0.001\% ≤ S + Se + Te ≤ 0.015\%}$$

the remainder being iron and impurities resulting from the preparation, the chemical composition satisfying, moreover, the relation: $$\text{0\% ≤ Nb + Ta + Ti + Al ≤ 1\%}$$

Preferably, the chemical composition is such that: $$\text{0.005\% ≤ Ti ≤ 0.05\% 0.001\% ≤ Hf + Zr ≤ 0.025\%}$$

et il est souhaitable que: $$\text{0,005\% ≤ C ≤ 0,02 \%}$$

It is also preferable that: $$\text{0.002\% ≤ S ≤ 0.007\%}$$

and it is desirable that: $$\text{0.005\% ≤ C ≤ 0.02\%}$$

Preferably, the manganese content must be greater than 0.05% and it need not be greater than 1%. Likewise, it is preferable that Nb + Ta ≤ 0.05%.

$$\text{Ca ≤ 0,0025\%}$$

$$\text{Al ≤ 0,05\%}$$

$$\text{O < 0,0025\%}$$

$$\text{N < 0,005\%}$$

$$\text{P < 0,01\%}$$

$$\text{Sc + Y + La + Ce + Pr + Nd + Sm < 0,01\%}$$

It is desirable that the contents of impurities are such that: $$\text{Mg <0.001\%}$$

$$\text{Ca ≤ 0.0025\%}$$

$$\text{Al ≤ 0.05\%}$$

$$\text{O <0.0025\%}$$

$$\text{N <0.005\%}$$

$$\text{P <0.01\%}$$

$$\text{Sc + Y + La + Ce + Pr + Nd + Sm <0.01\%}$$

The invention also relates to a cold-rolled strip of iron-nickel alloy according to the invention whose recrystallization texture is cubic of the type (100) <001>, and its use for the manufacture of a shadow mask for tube. cathode visualization or toric magnetic core.

The invention will now be described in a more precise but nonlimiting manner, and will be illustrated by the examples which follow.

The inventors have found, unexpectedly, that by adding to an iron-nickel alloy otherwise in accordance with the prior art, a small amount of titanium, accompanied, possibly, small amounts of Zr or Hf, in the presence of small amounts of S, Se or Te, and possibly of Nb, Ta, C or Mn, the annealing temperature range of the alloy was very significantly enlarged, making it possible to obtain a cubic texture (100) <001> very favorable for obtaining good magnetic properties. With these additions, the width of the satisfactory temperature range exceeds 50 ° C., while this width is usually less than 25 ° C.

The iron-nickel alloys concerned capable of exhibiting a cubic structure mainly contain iron and nickel, the nickel possibly being partially substituted by cobalt. They can also contain, in particular, copper, manganese, molybdenum, tungsten, vanadium, chromium and silicon.

$$\text{0\% ≤ Co + Cu + Mn ≤ 10\%}$$

$$\text{0\% ≤ Mo + W + Cr ≤ 4\%}$$

$$\text{0\% ≤ V + Si ≤ 2\%}$$

Expressed by weight%, the contents of these elements are such that: $$\text{30\% ≤ Ni + Co ≤ 85\%}$$

$$\text{0\% ≤ Co + Cu + Mn ≤ 10\%}$$

$$\text{0\% ≤ Mo + W + Cr ≤ 4\%}$$

$$\text{0\% ≤ V + If ≤ 2\%}$$

The rest of the composition consists of iron, the elements specific to the invention, and impurities.

So that these alloys can have a cubic structure, it is also necessary that, if they contain titanium, aluminum, niobium or tantalum, we have: $$\text{Ti + Al + Nb + Ta ≤ 1\%}$$

$$\text{Ca < 0,0025\%}$$

$$\text{Al < 0,05\%}$$

$$\text{0 < 0,0025\%}$$

$$\text{N < 0,005\%}$$

$$\text{P < 0,01\%}$$

$$\text{Sc + Y + La + Ce + Pr + Nd + Sm < 0,01\%}$$

The impurities are, in particular, magnesium, calcium, aluminum, oxygen, nitrogen, phosphorus and rare earths. Preferably, the contents of these elements are such that: $$\text{Mg <0.001\%}$$

$$\text{Ca <0.0025\%}$$

$$\text{Al <0.05\%}$$

$$\text{0 <0.0025\%}$$

$$\text{N <0.005\%}$$

$$\text{P <0.01\%}$$

$$\text{Sc + Y + La + Ce + Pr + Nd + Sm <0.01\%}$$

• de 0,003% à 0,15% de titane,
• éventuellement, au moins un élément pris parmi Zr et Hf, la somme des teneurs en Ti, Zr et Hf étant comprise entre 0,003% et 0,15%; il est préférable d'avoir simultanément 0,005% ≤ Ti ≤ 0,05% et 0,001% ≤ Hf + Zr ≤ 0,025%;
• de 0,003% à 0,05%, et de préférence, de 0,005% à 0,02% de carbone;
• éventuellement au moins un élément pris parmi Nb et Ta, la somme des teneurs en ces éléments ne dépassant pas, de préférence, 0,05%;
• de préférence, plus de 0,05% de manganèse; lorsqu'une forte addition de manganèse n'est pas utile ou pas souhaitable, la teneur en cet élément est limitée à 1%.

According to the invention, the alloy contains:

• from 0.003% to 0.15% titanium,
• optionally, at least one element taken from Zr and Hf, the sum of the contents of Ti, Zr and Hf being between 0.003% and 0.15%; it is preferable to have simultaneously 0.005% ≤ Ti ≤ 0.05% and 0.001% ≤ Hf + Zr ≤ 0.025%;
• from 0.003% to 0.05%, and preferably from 0.005% to 0.02% carbon;
• optionally at least one element taken from Nb and Ta, the sum of the contents of these elements preferably not exceeding 0.05%;
• preferably more than 0.05% manganese; when a strong addition of manganese is not useful or undesirable, the content of this element is limited to 1%.

This alloy can be produced in an arc furnace, continuously cast in the form of a slab or thin strip, or in an ingot, then hot rolled in the form of a hot strip. The hot strip is then cold rolled with a work hardening rate greater than 80%, and preferably greater than or equal to 90%, to obtain a cold rolled strip.

$$\text{Bm-Br < 400 Gauss}$$

$$\begin{gathered} \text{H1 compris entre 0,15 et 0,30 Oersteds} \\ \text{ΔH < 0,035 Oersteds.} \end{gathered}$$

When the cold-rolled strip is intended for the production of toric magnetic cores, the annealing must give the alloy not only a cubic texture, but also a weakest coercive field possible. In this case, it is preferable, first, to cut and wind the strip to form a toric core. The O-ring is then annealed at a temperature between 850 ° C and 1200 ° C to cause primary recrystallization which generates the formation of a cubic texture (100) <001>. The annealing temperature must be adjusted to, on the one hand, remain below the critical secondary recrystallization temperature with giant grains, and, on the other hand, so that the quantities Bm, Bm-Br, H1 and ΔH measured by the CCFR method according to ASTM A598-92 in the chapter "Standard Method For Magnetic Properties of Magnetic Amplifier Cores" are such that: $$\text{Bm> 14500 Gauss}$$

$$\text{Bm-Br <400 Gauss}$$

$$\begin{gathered} \text{H1 between 0.15 and 0.30 Oersteds} \\ \text{ΔH <0.035 Oersteds.} \end{gathered}$$

The heat treatment can also be carried out directly on the cold-rolled strip, with possibly less constraints on the search for magnetic properties. This is, in particular, the case when the nickel content is close to 36% and the strip is used for the manufacture of shadow masks for cathode-ray viewing tubes; the cubic texture is, in fact, particularly favorable for a good quality of the drilling of holes by chemical etching. Annealing is then carried out at a temperature above 550 ° C. and below the secondary recrystallization temperature. When it is not essential to have a particularly low coercive field, the annealing temperature is generally less than 800 ° C.

By way of example, and in order to highlight the effects of the invention, the critical temperature for the appearance of secondary recrystallization with giant grains of the alloys A (according to the prior art) and B (according to the invention) cold rolled with hardening rates of 83%, 90% and 95%. Critical temperatures were determined using a thermal gradient oven.

The chemical compositions of the alloys were, by weight%: Fe Or Mn Yes VS S Al Ti Hf AT ball 36.1 0.4 0.09 0.005 7 ppm <0.005 0 0 B ball 36.4 0.3 0.1 0.012 30ppm 0.01 0.019 0.007

For the different work hardening rates, the critical temperatures were: 83% 90% 95% AT 970 ° C 1020 ° C 1040 ° C B 1060 ° C 1090 ° C 1090 ° C

These examples show that the alloy according to the invention retains a cubic structure at a temperature greater than 1050 ° C. even for a relatively low work hardening rate (83%), and, in all cases, greater than 50 ° C. recrystallization temperatures of the alloy according to the prior art.

Also by way of example and comparison, the alloys 1, 2 and 3 were manufactured according to the prior art and the alloys 4, 5 and 6 according to the invention. These alloys were cold rolled in the form of strips of 0.05 mm thick with work hardening rates of 95%, then the annealing temperature range was determined making it possible to obtain a cubic structure (100) < 001> as well as the magnetic properties mentioned above.

The chemical compositions were, in% by weight: alloy Fe * Or Mn Yes VS S Al Ti Zr Hf Nb 1 Ball 47.5 0.38 0.1 0.007 0.005 <0.005 - - - - 2 Ball 47.8 0.51 0.21 0.005 0.005 <0.005 - - - - 3 Ball 48 0.49 0.23 0.001 0.004 <0.005 - - - - 4 Ball 47.5 0.48 0.22 0.009 0.005 <0.005 0.021 0.003 - - 5 Ball 47.4 0.49 0.24 0.008 0.004 0.011 0.023 - - 0.02 6 Ball 47.5 0.26 0.01 0.0011 0.005 0.015 0.023 - 0.002 0.026 * Fe and impurities

The magnetic properties and the satisfactory annealing temperature range were: alloy Bm (gauss) Bm-Br (gauss) H1 (Oersteds) ΔH (Oersteds) Θ satisfactory annealing ° C 1 14800 140 0.34 0.042 - 2 14500 170 0.36 0.021 - 3 14600 240 0.27 0.032 975/1000 4 14500 190 0.28 0.029 1040/1100 5 14700 130 0.28 0.024 950/1050 6 15000 140 0.26 0.031 1000/1100

It can be seen from these results that with alloys 1 and 2 according to the prior art it is not possible to obtain all of the magnetic characteristics required, namely: Bm> 14500 Gauss, Bm-Br <400 Gauss, H1 between 0.15 and 0.30 Oersteds, ΔH <0.035 Oersteds. For alloy 3 according to the prior art, the satisfactory annealing temperature range has a range of 25 ° C, whereas, for alloys 4, 5 and 6, the satisfactory annealing temperature range has a range of 60 ° C, 100 ° C and 100 ° C respectively. These examples clearly illustrate the difficulties encountered with the alloys according to the prior art and the advantage provided by the invention.

Claims (13)

Iron-nickel alloy characterized in that its chemical composition comprises, by weight: $$\text{30\% ≤ Ni + Co ≤ 85\%}$$

$$\text{0\% ≤ Co + Cu + Mn ≤ 10\%}$$

$$\text{0\% ≤ Mo + W + Cr ≤ 4\%}$$

$$\text{0\% ≤ V + If ≤ 2\%}$$

$$\text{0\% ≤ Nb + Ta ≤ 1\%}$$

$$\text{0.003\% ≤ C ≤ 0.05\%}$$

$$\text{0.003\% ≤ Ti ≤ 0.15\%}$$

$$\text{0.003\% ≤ Ti + Zr + Hf ≤ 0.15\%}$$

$$\text{0.001\% <S + Se + Te <0.015\%}$$

the remainder being iron and impurities resulting from the preparation, the chemical composition satisfying, in addition the relationship: $$\text{0\% ≤ Nb + Ta + Ti + Al ≤ 1\%}$$

Iron-nickel alloy according to claim 1 characterized in that: $$\text{0.005\% ≤ Ti ≤ 0.05\%}$$

$$\text{0.001\% ≤ Hf + Zr ≤ 0.025\%}$$

Iron-nickel alloy according to claim 1 or claim 2 characterized in that: $$\text{0.002\% ≤ S ≤ 0.007\%}$$

Iron-nickel alloy according to any one of Claims 1 to 3, characterized in that: $$\text{0.005\% ≤ C ≤ 0.02\%}$$

Iron-nickel alloy according to any one of Claims 1 to 4, characterized in that: $$\text{0.05\% ≤ Mn}$$

Iron-nickel alloy according to any one of Claims 1 to 5, characterized in that: $$\text{Mn ≤ 1\%}$$

Iron-nickel alloy according to any one of Claims 1 to 6, characterized in that: $$\text{Nb + Ta ≤ 0.05\%}$$

Iron-nickel alloy according to any one of Claims 1 to 7, characterized in that the impurity contents are such that: $$\text{Mg <0.001\%}$$

$$\text{Ca <0.0025\%}$$

$$\text{Al <0.05\%}$$

$$\text{O <0.0025\%}$$

$$\text{N <0.005\%}$$

$$\text{P <0.01\%}$$

$$\text{Sc + Y + La + Ce + Pr + Nd + Sm <0.01\%}$$

Method for manufacturing a cold-rolled alloy strip according to any one of Claims 1 to 8 having a cubic texture, characterized in that: - we make a hot rolled strip, - the strip is cold rolled with a work hardening rate greater than 80%, - And the cold strip is annealed at a temperature above 550 ° C and below the secondary recrystallization temperature of the alloy, to give it a cubic texture. Method for manufacturing a toroidal magnetic alloy core according to any one of Claims 1 to 8, characterized in that: - a cold rolled strip is manufactured having a work hardening rate of more than 80%, - the strip is cut and rolled up to form an O-ring, - And the ring core is annealed at a temperature above 850 ° C and below the secondary recrystallization temperature of the alloy. Cold-rolled strip of iron-nickel alloy according to any one of claims 1 to 8, the recrystallization texture of which is cubic of the type (100) <001>. Use of a strip according to claim 11 for the manufacture of a shadow mask for cathode-ray display tube. A toroidal magnetic alloy core according to any one of claims 1 to 8 having a cubic texture.