SU33547A1 - Manganese non-magnetic steel - Google Patents

Description

The materials used to make resistance elements so far are nickel-based alloys (with the exception of some manganin grades containing 4-41% Ni), such as nickeline (20-32% Ni), constantan (40-50% Ni ), kruppin (30% nickel), nichrome (65-80% Ni), etc.

The electrical resistivity of these alloys is approximately as follows: nickel 33 micro-ohms per cm, constantan-49 micro-ohms per cm, nichrome-110 micro-ohms per cm, maiganin-43 micro ohms per cm.

In addition to resistivity, in limited cases it is important to have a low temperature coefficient of electrical resistance. Finally, the material for C01 motivations must also have certain mechanical properties, mainly high viscosity and plasticity, in order to be easily pulled into the wire, wound in spirals, etc.

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All of the above materials are very expensive because they contain a very large amount of nickel, copper and often other expensive pure metals.

For cable armor, a material is required that would have a low permeability, i.e. would be practically non-magnetic, which makes the hysteresis loss close to zero, the electrical resistance as high as possible, which reduces the Foucault current loss, certain mechanical properties (see below) and would be well drawn into the wire.

According to technical conditions, this material should have the following basic properties: magnetic permeability not higher than 8-10; tear resistance not lower than 40 kg; relative lengthening is not lower than 10-15%; good wire drawing.

As a material for this purpose, a whole range of compounds are still known, such as steel with 9-15% nickel.

3i - 5% chromium, 3-5% manganese, the rest iron; steel with 5% Ni, 7% Mn and 1% G, etc.

As shown in the above formulations, all materials contain an expensive nickel.

The subject of the present invention is a material for resistive resistances and for cable armor, containing absolutely no nickel or other jioporHX components.

The chemical composition of this material is as follows: carbon-0.3-1%, manganese-15-22%, silicon -0 ,,%, copper 1 -4%, the rest is iron.

The structure of this material must be austenitic, which mainly determines the limits of the content of individual elements and heat treatment conditions.

Carbon above the upper limit contributes to obtaining a large number of carbides, which requires a very high quenching temperature to convert them into solution.

When the content is less than 0.3% C, a sufficiently stable austenite is not obtained.

From the ideas of obtaining a sufficiently stable austenite, the limits of manganese content should also be observed.

Silicon greatly increases the electrical resistivity of the material and, hence, its temperature coefficient. Therefore, the silicon content varies depending on the exact purpose of the material.

Copper lowers the temperature coefficient and slightly improves the material's ability to drag.

The electrical magnetic and mechanical properties of this material depend not only on the chemical composition, but also on the conditions of its thermal and mechanical processing. The latter is, in general, quenching with a temperature of 800-1050 ° in water, and the duration of exposure at the quenching temperature depends on the diameter of the wire.

According to the inventors' research, the magnetic permeability of this material is 1.3, the specific electrical resistance is 92 micro-ohms per SL, the temperature coefficient is (O- 100 °) -0,0006, the tear resistance is 86 kg1 mm elongation-: 48%.

The material is very well drawn in the wire. have a cold way. For comparison, it can be stated that it is drawn in the same way as for carbon steel with 0.5-0.6% carbon. The material after heat treatment is extremely plastic.

The material can be melted like an electric furnace or from an open-hearth furnace. Before being drawn, it can be forged or rolled. The initial temperature of its forging or rolling is 1000-1050 °. The final temperature is about 750-800.

The economic effect from the use of this new material, according to the inventors, is extremely large.

According to further studies of the inventors, the proposed steel is also suitable for the manufacture of heating elements in electric heating devices, and also for bandage wire (for bonding windings in electric machines). For the latter purpose, a special bronze wire is used. Tests on heating devices showed the full suitability of the proposed material for most of these devices. It is also possible to use it for auto-candles instead of nickelin.

Silicon, in addition to this effect, greatly increases the temporary resistance of the material, leading to erq, up to 120 KiJMM and above, without decreasing the elongation.

Additional studies have shown that copper in an amount of from 1 to 4% extremely improves the viscosity of the material, bringing the relative elongation to 65% and narrowing the cross-section to 71%. Detailed studies of the effect of cooling rate during heat treatment on properties have shown that not only is there no need to cool in water, but it is even desirable to cool slowly, because when cooled in water, under the influence of thermal stresses, the properties deteriorate first. magnetic./ Since the cooling in the furnace and in the air does not give a significant difference, it is possible to prefer the cooling in air for economic reasons. For the same

for this reason, it is necessary to recommend a lower heat treatment temperature (up to 700 °).

Inventors carried out studies with an additive to the proposed aluminum steel, which showed that in amounts from 0.5 to 2% aluminum improves primary crystallization, significantly increases the electrical resistivity and lowers the temperature coefficient. Therefore, aluminum in the specified amounts for most applications of the material must be introduced.

The proposed manganese non-magnetic steel is resistant against oxidation to a temperature of 550 °.

Work of wire and similar products at higher temperatures is unprofitable, as the wire quickly burns out. Therefore, the inventors have undertaken a study to find a surface coating that gives reliable oxides to prevent further oxidation at high temperatures.

Electroplating with chromium turned out to be the most suitable for this purpose.

For this purpose, products of complex shape are chrome plated in the usual way, while products of a great length and constant cross section are drawn through the electrolyte at a fixed rate.

After applying a layer of xpolla, the product is subjected to annealing between 700-1000 ° C, and a heat-resistant layer of chromium oxide forms on the surface of the coating, and the inner layers of chromium diffuse into the alloy, so that the coating is sufficiently strong to withstand plastic deformations.

In addition, since the proprietary oxides of the proposed steel do not have sufficient dielectric properties necessary for the production of Rustrat-type rheostats without a special insulation coating, and since chromium oxide has sufficient electrical resistance for the above purpose, the wire of the proposed steel treated by the above method is suitable For the production of rustat rheostats, only the required chromium layer can be much thinner.

The subject matter of the invention.

Claims (2)

1. Manganese non-magnetic steel, containing 15-22% Mn and up to% C, characterized in that, in addition to the addition of 0.5 to 4% Si, which is known in relation to non-magnetic steel grades, copper is introduced in an amount from 1 to four%. 2. Steel according to claim 1, characterized in that aluminum is additionally added to its composition.