CS222876B1 - Silicon-silicon-man-made converters for electrotechnical transformer sheets and its production method - Google Patents

Abstract

The invention relates to silicon steel, mainly produced in converters for electrotechnical transformer sheets, with a mass content of 2.9 to 4.25% silicon, 0.02 to 0.04% carbon, 0.05 to 0.12% manganese, traces of up to 0.015% phosphorus and traces of up to 0.015% sulfur, as well as a process for its production, which solves the problem of significantly improving the magnetic properties of oriented sheet metal strips and speeding up their production in converters. Improving the magnetic properties of oriented transformer strips is of great importance in the field of reducing the dimensions of manufactured devices and thereby reducing their weight. The magnetic properties of the material are expressed by the function of several factors such as chemical composition, segregation, grain size, amount and morphology of impurities, state of tension, crystallographic orientation, etc. The technology for producing oriented transformer strips The strip must be designed to meet the basic conditions for the formation of the vast majority of grains in the (110) [011] orientation, i.e. Goss texture. There are known efforts to solve the problem by reducing specific losses and increasing magnetic induction, while the production method and chemical composition of the steel, including technology, especially in the production of steel in the con 2

Description

The invention relates to silicon steel, mainly produced in converters for electrotechnical transformer sheets, with a mass composition of 2.9 to 4.25% silicon, 0.02 to 0.04% carbon, 0.05 to 0.12% manganese, traces of up to 0.015% phosphorus and traces of up to 0.015% sulfur, as a method of its production, which solves the problem of significantly improving the magnetic properties of oriented sheet metal strips and speeding up their production in converters.

Improving the magnetic properties of oriented transformer strips is of great importance in the field of reducing the dimensions of manufactured devices and thus reducing their weight. The magnetic properties of the material are expressed as a function of several factors such as chemical composition, segregation, grain size, amount and morphology of impurities, state of tension, crystallographic orientation, etc. The technology for producing oriented transformer strips must be designed in such a way as to meet the basic conditions for the formation of the vast majority of grains in the (110) [011] orientation, i.e. Goss texture.

There are known efforts to solve the problem by reducing specific losses and increasing magnetic induction, while the production method used and the chemical composition of steel, including the technology used, especially in the production of steel in converters, do not offer prospects for a significant improvement in the magnetic properties of transformer sheet metal strips.

The above-mentioned shortcomings are eliminated and the problem is solved by silicon steel, especially produced in converters for electrotechnical transformer sheets according to the invention and with a mass composition of 2.9 to 4.25% silicon, 0.02 to 0.04% carbon, 0.05 to 0.12% manganese, traces of up to 0.015% phosphorus and traces of up to 0.015% sulfur. The essence of the invention lies in the fact that the steel further contains antimony in a mass concentration of 0.01 to 0.2% and nitrogen in a mass concentration of 0.001 to 0.008%, preferably the steel further contains chromium in a mass concentration of 0.001 to 0.05%, copper in a mass concentration of 0.001 to 0.1%, nickel in a mass concentration of 0.001 to 0.1%, aluminum in a trace amount of up to 0.015%, selenium in a trace amount of up to 0.025%. The essence of the production of this steel lies in the fact that antimony and selenium are added, before casting the liquid steel, by placing it on the bottom of the mold in the form of a ferroalloy Fe ₃ Sb ₂ in a fraction of 3-8 mm in the solid state.

The advantages of the steel and the method of its production according to the invention over the state of the art in the world are that it can be produced using conventional technology in converters. The resulting product has a grain orientation predominantly in the (110) [001] orientation.

A 'ii «I, WifŮr W*» . .

This orientation is supported by a small amount of antimony by preventing the growth of grains deviating from this orientation. The resulting optimum texture is produced by high-temperature annealing. Examples of embodiments of steel according to the invention:

Example 1

Four laboratory melts were made using the induction melting method in a vacuum induction furnace. Electrolytic iron with a purity of 99.99% by weight of iron, spectrally pure silicon and antimony were used. Antimony alloying was carried out by adding the Fe ₃ Sb ₂ master alloy to the melt. The mass concentration of the elements in the melts is given in Table 1.

Table 1 melting

Composition by weight in %

silicon antimony nitrogen carbon sulfur 1 3.02 0 4 x IQ" ⁴ 5 x 10" ⁴ 2 x 10~ ⁴ 2 3.01 0.007 2 x 10 5 x 10" ⁴ 2 x 10 ⁴ 3 3.02 0.140 7 x 10" ⁴ 5 x 10 “ ⁴ 2 x 10~« 4 3.00 0.120 7 x 10~ ⁴ 5 x 10" ⁴ 2 x 10" ⁴ Ingots from produced alloys the abovementioned the by weight composition 60 % antimony,

The compositions were hot and cold rolled to a thickness of 0.30 mm and highly thermally annealed. The results showed that in melts 3 and 4 with a mass content of antimony in % 0.140 and 0.120, this element positively influences the formation and overall representation of the Goss texture. Further laboratory results showed that the minimum mass content of antimony, which will be actively manifested, is 0.01%. Example 2

The steel was produced using the nitridical variant of single-pan technology in a converter. Liquid pig iron, scrap, ferrosilicon, lime and other additives in appropriate quantities were used for production.

The steel was cast at a temperature of 1550 °C into molds with dimensions of ——-——— mm.

1060x860

The mass composition of the elements in the melt analysis was; as follows: carbon 0.02 %/o, manganese 0.07 %, silicon 3.15 %, phosphorus 0.006 %, sulfur 0.014 %, aluminum 0.003 %, nitrogen 0.007, copper 0.037 %, nickel 0.004 %, chromium 0.019 %, arsenic 0.003 %. For verification according to the invention, 3 ingots were selected from the melt and cast in sequence into molds No. 6, No. 7 and No. 8. At the bottom of the molds with a final weight of one ingot of 11.7 tons, a solid state Fe ₃ Sb ₂ master alloy in a fraction of 3 to 8 mm was added. The master alloy for the experimental ingots in an amount of 50 kg was produced by melting pure; antimony with low-carbon iron in an induction furnace. The produced master alloy Fe ₃ Sb ₂ contained 0.61% silicon, 0.072% carbon, 0.019% sulphur, 0.046% aluminium, 0.004% nitrogen and 0.002% oxygen. The amount of master alloy added to the ingots was chosen so that the resulting mass concentration of antimony was in the range of 0.03 to 0.06%. Chemical analysis of the experimental ingots showed that the mass concentration of antimony was 0.04% in one ingot and 0.05% in the other two ingots. The steel produced was used to make a steel strip with a thickness of 0.35 mm by hot and cold rolling. By measuring the physical characteristics of the final products, i.e. transformers

sheet metal thickness 0.35 mm average values: these were achieved for P 1.5/50 0.97 (W.kg ^-1 ) P 1.7/50 1.34 (W.kg ^-1 ) B 500 1.78 (T) B 1000 1.83 (T)

The transformer steel according to the invention has shown good utility properties and its application in practice will be associated with substantial economic benefits.

The invention can be used primarily in the production of transformers, thereby reducing their weight and thus saving high-quality metal material. The invention can also be used in the production of other electrical equipment. Low specific losses will allow for the reduction of no-load losses and thus saving electrical energy. Reducing the dimensions of transformers will reduce processing and investment costs.

Claims (3)

1. Silicon steel, in particular manufactured in converters, for electrotechnical transformer sheets weighing 2,9 to 4,25% by weight of silicon, 0,02 to 0,04% of carbon, 0,05 to 0,12% of manganese, traces up to 0.015% phosphorus and traces up to 0.015% sulfur, characterized in that it further comprises, in a weight concentration, an antimony in the range of 0.01 to 0.2% and a nitrogen in the range of 0.001 to 0.008%. 2. The silicon steel of claim 1, further comprising a chromium content in the range 0.001 to 0.05%, a copper content in the range 0.001 to 0.1 nickel in an amount of 0.001 to 0.1%, aluminum at a trace amount of up to 0.015% and selenium at a trace amount of up to 0.025%. 3. A process according to claim 1, wherein the antimony and optionally selenium are added before casting of the liquid steel, by placing it on the bottom of the ingot mold in the form of a ferroalloy Fe ₃ Sb ₂ in fractions of 3-8 mm in the solid state.