JP2007314885A - Soft magnetic material with low coercive field strength, high permeability and improved resistance to corrosion - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To melt a soft magnetic nickel-iron alloy satisfying the mentioned requirements to magnetic properties, corrosion resistance and wear resistance and also preferably used for a series of preferable applications in the case of a soft magnetic component. <P>SOLUTION: The invention relates to a soft magnetic nickel-iron alloy containing 35 to 65 mass% nickel, one or several of the rare earths cerium, lanthanum, praseodymium or neodymium and the impurities introduced during smelting, the sum of the rare earths being between 0.003 to 0.05 mass%, and the ratio of the sum of the rare earths by mass% is higher than the sulfur content by mass% at least by 4.4 times. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a soft magnetic nickel iron alloy.

  From the description of Carl Heck's book "Magnetische Werkstoffe und ihre technische Anwendung", Huetig Verlag, Heidelberg 1975, p. 349 et seq. is there.

  The main requirement of the material is a high saturation current density, high permeability to achieve a large magnetic coercivity with little energy, and thus a little strength of the magnetic field, ie a small excitation current as well as a high current density. It can be generated in the air gap and thus a large attractive force acts on the anchor. The slight coercivity allows the relay to be slightly opened during the back swing of the excitation current.

  Along with magnetic requirements, relay materials still require corrosion resistance in alternating weathering tests. This is because the correct functioning of the relay is required in all weather conditions. This requirement can only be achieved by additionally coating the finished member with a corrosion-resistant layer in the case of materials with insufficient corrosion resistance.

  The contact surface between the anchor and the yoke must have as little gap as possible in order to achieve a high permeability of the magnetic circuit consisting of the yoke and the anchor. This contact surface must not be damaged by opening and closing of the relay. This is because in this case, the trigger current of the relay changes.

  Similar requirements apply to other molded and stamped metal members made of soft magnetic material.

  The magnetic requirements for the relay material are described in DIN 17405 "Weichmagnetische Werkstoffe fuer Gleichstromrelais". The following Table 1 shows an excerpt from DIN 17405.

  DIN 17745 “Knetlegierungen aus Nickel und Eisen” describes alloy Ni48 (material numbers 1.3926 and 1.3927) as starting material for types RNi 12 and RNi 8 (See Table 2). Alloy Ni36 (material number 1.3911) is the starting material for type RNi24.

  When melting nickel-iron alloys, deoxidizing and / or desulfurizing elements such as manganese, silicon and aluminum are still required along with the desired alloying elements. In addition, if the alloy is produced using conventional steelmaking techniques for advantageous costs, some minimum of oxygen, sulfur, phosphorus, carbon, calcium, magnesium, chromium, molybdenum, copper and cobalt. Admixtures can be avoided. In this case, normal steelmaking techniques are understood to be ladle metallurgy and / or VOD treatment for melting in an open arc furnace and subsequent deoxidation, desulfurization and degasification. Thereafter, the flat steel pieces for block or strand cast plates are hot deformed in one or two steps to a thickness of about 4 mm, and in some cases cold deformed to the final thickness with intermediate heating. The magnetic properties are degraded by admixtures of carbon, nitrogen, oxygen, sulfur and non-metallic inclusions, as described for example in DE 1961556 A1. Non-metallic impurities are produced by casting due to the required deoxidation and / or desulfurization of the melt. Depending on the deoxidizer and / or desulfurizer, for example, oxides of calcium, magnesium or aluminum are present.

Therefore, in order to avoid the above-mentioned difficulty, soft magnetic materials having the highest requirements according to the state of the art so far are disclosed in DE 3910147 and DE 1259367. Manufactured by vacuum technology using selected clean use materials. Another method known from the publication is described in German Offenlegungsschrift DE 4 105 507, which is very costly under vacuum or under protective gas of blocks previously melted under vacuum or under protective gas. This is an expensive electric sludge remelting method.
German Patent Application Publication No. 19612556 A1 German Patent Application Publication No. 3910147 German Patent No. 1259367 German Patent Application Publication No. 4105507 arl Heck's book "Magnetische Werkstoffe und ihre technische Anwendung", Huetig Verlag, Heidelberg 1975, p. 349 et seq.

  The problem underlying the present invention is a soft magnetic iron-nickel alloy that meets the requirements described for magnetic properties, corrosion resistance and wear resistance and is used in a series of preferred applications in the case of soft magnetic components. It is to melt.

  This task has a nickel content of 35 to 65% by weight and one or more of the rare earths cerium, lanthanum, praseodymium or neodymium and impurities inevitable for melting, in which case the sum of the rare earths is 0.003 This is solved by a soft magnetic iron-nickel alloy, which is ˜0.05% by mass and the proportion of the sum of the rare earth content in mass% is at least 4.4 times greater than the sulfur content in mass%.

  Other preferred embodiments of the subject of the invention can be ascertained from the dependent claims to which they belong.

  The alloys according to the invention are preferably produced by steelmaking techniques, ie melting in an open arc furnace and subsequent ladle metallurgy and / or VOD treatment for deoxidation, desulfurization and degassing. Thereafter, the flat steel slab for the block or strand cast plate is hot deformed to a thickness of about 4 mm in one or two steps in order to adjust the hardness required for the production of members from this strip. Then, in some cases, it is cold deformed to the final thickness with intermediate heating.

  Following manufacture of the member from the alloy and burning of the member at a temperature of 800-1150 ° C., a coercivity of less than 8 A / m can be achieved using the member.

  The advantageous use of the alloys according to the invention is inter alia relay members, for example yokes and anchors.

Furthermore, the iron-nickel alloy according to the invention can still be advantageously used for the following cases:
-The valve lid and top of the solenoid valve,
-Yokes or pole parts or pole pieces or ultrathin plates and anchors for stationary and electromagnets,
-Spool core, step-by-step motor stator and motor rotor and stator,
-Sensor moldings and stamped metal parts, position sercine and position receiver;
-Magnetic head and magnetic head shielding,
-Shielding, eg motor shielding, shielding containers for display equipment and shielding for cathode tubes.

  From a 1.2 mm thick strip produced by steelmaking technology, flat specimens are stamped, cleaned, heat treated at 1080 ° C./4 hours under hydrogen atmosphere, and then heated to 300 ° C. in a furnace. Cooled down. For this specimen, the weathering test described in DIN 50017 was carried out for 28 hours at 55 ° C./90-96% air humidity for 8 hours and at 25 ° C. and 95-99% air humidity for 16 hours. Alloys with a nickel content of 36% to 81% by weight and partially with additives such as chromium, copper and / or molybdenum were tested (see Table 3). Alloys with a nickel content of 55% by weight or less show a significantly stronger corrosion resistance on the surface than alloys with a nickel content higher than 75% after the end of the alternating weathering test (B. Gehrmann, H. Hattendorf, A. Kolb-Telieps, W. Kramer, W. Moettgen, Material and Corrosion 48, 535-541 (1997)), therefore, without additional means to improve corrosion resistance, The above requirements for relay material are not met. In contrast, the properties required by DIN 17405 were fulfilled as indicated by the coercivity Hc exemplarily described in Table 3 (prior art).

  Sulfur was measured at the corroded position of the specimen after the end of the alternating REM / EDX weathering test.

  The improvement according to the invention of the corrosion behavior is surprisingly achieved by desulfurizing with Cor a corrosion sensitive nickel iron alloy having a nickel content of 35% to 65% by weight. In this case, this is preferably carried out using mixed metals from rare earth cerium and / or lanthanum and / or praseodymium and / or neodymium which are very similar in chemical behavior. Sufficient rare earth atoms must be present to ensure that the sulfur is bound overall. This is the case, for example, when starting from the formation of sulfide sulfide CeS with the majority cerium content, ie when more cerium atoms are present in the alloy than sulfur atoms.

  Thereafter, the cerium content in wt.% Must be at least 4.4 times greater than the sulfur content in wt.% In order to achieve complete binding of sulfur by cerium. The same applies to the total content of other rare earth lanthanum, praseodymium and / or neodymium and rare earth.

  As already mentioned above, the addition of such strong deoxidizers and desulfurizers such as cerium can impair the magnetic properties by reaction products remaining in the material (A. Hoffmann, Ueber den Einfluss von verschiedenen Desoxidationselementen auf die Verformung und die Anfangspermeabilitaet von Ni-Fe-Legierungen, Z. angew. Physik 32, pp. 236-241). Surprisingly, the addition of rare earths can be metered such that the permeability and coercivity magnetic values are within the normal range of fluctuations of the melt melted according to the state of the art.

  The deoxidation residue protrudes from the contact surface of the relay and remains between these contact surfaces, and when the relay is opened and closed later, due to the high hardness in the case of oxide residue, for example, the finely polished contact surface is It is known that it can be destroyed. Accordingly, the relay material may have only a very small content of non-metallic inclusions according to DIN 50602 (Method M). Therefore, even in the case of deoxidation using cerium or a mixed metal from rare earth cerium, lanthanum, praseodymium, neodymium, the value of the maximum size of the streak-shaped sulfide inclusion SS is 0. The maximum dimension value of oxide inclusions OA (aluminum oxide) in dissolved form must be less than 1 or less than 1.1 and is less than 2.2 or less than 3.2 or less than 4.2 And the maximum dimension value of the oxide inclusions OS (silicate) in the form of streaks must be less than 5.2 or less than 6.2 or less than 7.2 and the oxidation of the granular form The maximum dimension value of the inclusion inclusion OG must be less than 8.2 or less than 9.2.

  As an example, nickel iron alloys with about 48% nickel and slight additions of manganese and silicon were melted using steelmaking techniques in a 30 ton arc furnace (charges E5407 and E0545), with very similar compositions. There was a comparison with the rare earth additive-free charge (charges T4392, T5405 and T5406) corresponding to the state of the art. The exact composition is shown in Table 4.

  A small amount of boron may be added, as was done with charges T4392, T5405, T5406 and E5407, to improve punchability. The cerium content in mass% in the charges E5407 and E0545 according to the invention is about 4.4 times greater than the sulfur content in mass%.

  After melting, block rolling and subsequent hot strip rolling was performed at about 4 mm followed by cold re-deformation to a final thickness of 1.0 mm.

  From this, a circular specimen having a diameter of 25.5 mm was punched out. This is true for all charges up to E0545. In this case, an approximately 15 mm × 15 mm × 5 mm piece from a cast specimen with a finely polished surface was used. All specimens were cleaned and a portion of the specimens were heat treated in a hydrogen atmosphere at 970 ° C. for 6 hours and then cooled to below 300 ° C. in a furnace. The second part of the specimen was heat-treated at 1030 ° C./2 hours in a hydrogen atmosphere, and then cooled in the furnace to below 300 ° C. All specimens were subjected to a 2-day shortened weathering test with a temperature / moisture exchange of 3 hours periodicity from 25 ° C. and 55% air moisture to 55 ° C. and 98% air moisture. It was. In this case, the specimens were individually laid flat in a glass dish, so that on the lower side, the sharp conditions of crevice corrosion were still dominant. The results are shown in Table 5.

  In the case of the charges E5407 and E0545 according to the invention, no corrosion can be measured at all, whereas in the case of the two comparative charges T5405 and T5406, all specimens have corrosion points on both sides. It was actually measured.

Thus, the addition of strong deoxidizers and desulfurizers such as cerium can impair the magnetic properties due to the reaction products remaining in the material as described above. Surprisingly, the permeability and coercivity magnetic values exhibited by the charges E5407 and E0545 according to the present invention, as shown in Table 6, are the usual values of charges melted according to the state of the art. It is within the range of fluctuation.
Table 6: Measured values for specimens with a thickness of 1 mm after a magnetic value of the charge (T) according to the state of the art and after ignition at 1080 ° C./4 hours in a hydrogen atmosphere and after cooling to 450 ° C. in a furnace. The magnetic value of the charge (E) according to the invention. The composition of the charge is shown in Table 4.

  Two charges having a known state of the art composition described in Table 7 in terms of properties during block rolling and hot strip rolling were considered as second charges.

  The two charges are distinguished only by essentially different contents of rare earths.

  In the case of charge T0626 with a total rare earth content of 0.054%, cracks were formed during thermoforming, after which the blocks were scrap metal. Such a high rare earth content leads to poor thermal deformation behavior. In contrast, the charge T0624 is rolled into a block as well as a heat strip having a thickness of about 4 mm. Since rare earths have a chemically similar behavior, according to the present invention, the total content of rare earths cerium, lanthanum, praseodymium and neodymium is not more than 0. It can be limited to 05% by mass.

  Table 8 shows a test of the content of non-metallic inclusions according to DIN 50602 for various charges (T) according to the state of the art and charges (E) according to the invention.

Charge T2536 has a maximum dimension of 2.7 with streak-shaped oxide inclusions (Method M). This value is too high to use the charge as material for the relay member. This value results in wear to the contact surface of the relay and results in loss of relay functionality. Thus, according to the present invention, the content of non-metallic inclusions is limited as follows:
The maximum dimension value according to DIN 50602 of the streak-shaped sulfide inclusion SS is 0.1 or less or 1.1 or less, and according to DIN 50602 of the oxide inclusion OA (aluminum oxide) in a dissolved form The maximum dimension value is 2.2 or less, or 3.2 or less, or 4.2 or less, and the maximum dimension value according to DIN 50602 of the streak-shaped oxide inclusion OS (silicate) is 5.2 or less. Alternatively, the maximum dimension value according to DIN 50602 of the granular oxide inclusion OG is not more than 8.2 or not more than 9.2. All other charges listed in Table 8 meet the requirements for the content of non-metallic inclusions.

Claims (15)

  Having a nickel content of 35 to 65% by weight and one or more of the rare earths cerium, lanthanum, praseodymium, neodymium and impurities unavoidable for melting, in which case the sum of the rare earths is 0.003 to 0.05 Soft magnetic material that is mass%.   2. The soft magnetic material according to claim 1, wherein the alloy has a cerium content of up to 0.05% by weight.   Alloy is deoxidizing additive and / or desulfurizing additive up to 0.5 mass% manganese, up to 0.5 mass% silicon, up to 0.002 mass% magnesium, up to 0.002 mass% calcium and aluminum 2. A mixture of a maximum of 0.010% by weight, a maximum of 0.004% by weight of sulfur and a maximum of 0.004% by weight of oxygen and a small amount of other additives inevitable for melting. Or the soft-magnetic material of 2.   The soft magnetic material according to any one of claims 1 to 3, wherein the ratio of the sum of the rare earth contents in mass% is at least 4.4 times greater than the sulfur content in mass%.   5. A soft magnetic material according to claim 1, wherein the alloy contains up to 0.002% by weight of boron.   A method for melting a soft magnetic iron-nickel alloy according to any one of claims 1 to 5, wherein the material alloy is melted in an open arc furnace and then for deoxidation, desulfurization and degasification. The method for melting the soft magnetic iron-nickel alloy according to any one of claims 1 to 5, wherein ladle metallurgy and / or VOD treatment is performed. The following parameters in the molten alloy:
The maximum dimension value of the streak-shaped sulfide inclusion is less than 0.1 or less than 1.1;
The maximum dimension value of the oxide inclusions OA (aluminum oxide) in dissolved form is less than 2.2 or 3.2 or 4.2;
-The maximum dimension value of the oxide inclusions OS (silicate) in the form of streaks is less than 5.2 or 6.2 or 7.2;
The method according to claim 6, wherein the value of the maximum dimension of the particulate oxide inclusion OG is adjusted to 8.2 or 9.2.   The method according to claim 6 or 7, wherein a coercive force of less than 8 A / m is achieved after producing a member from the alloy and heating the member at a temperature between 800C and 1150C.   Use of the soft magnetic iron-nickel alloy according to any one of claims 1 to 8 as material for a relay member.   Use of the soft magnetic iron-nickel alloy according to any one of claims 1 to 8 as a material for a valve lid and a valve upper part of a solenoid valve.   Use of the soft magnetic iron-nickel alloy according to any one of claims 1 to 8 as a material for yokes or pole pieces or pole pieces or ultrathin plates and anchors for stationary magnets and electromagnets.   Use of the soft magnetic iron-nickel alloy according to any one of claims 1 to 8 as a material for a spool core, a step-by-step motor stator and a motor rotor and stator.   Use of the soft magnetic iron-nickel alloy according to any one of claims 1 to 8 as a material for the forming and stamping metal parts of the sensor, the position cell thin and the position receiver.   Use of the soft magnetic iron-nickel alloy according to any one of claims 1 to 8 as a material for magnetic heads and magnetic head shielding.   Use of the soft magnetic iron-nickel alloy according to any one of claims 1 to 8 as a material for shielding.