Structural steel

FIELD: metallurgy, in particular structural steel composition.

SUBSTANCE: claimed steel contains (mass %): carbon 0.42-0.54p; silicium 0.15-0.50; manganese 0.90-1.50; niobium 0.01-0.08; molybdenum 0.06-0.20; aluminum 0.005-0.060; titanium 0.019-0.045; sulfur 0.001-0.045; phosphorus 0.001-0.045; nitrogen less than 0.012; chromium, nickel and copper each not more than 0.30, and balance: iron. Steel of present invention is useful in production of pipelines for oil industry operating at temperature from 50°C to -10°C.

EFFECT: steel with optimum combination of strength and viscous properties.

2 tbl, 1 ex

 

The invention relates to metallurgy and, in particular, compositions of the steels used for the manufacture of seamless tubing and casing pipes for oil pipelines subjected during the operation of high static and cyclic loads and shock loads in the temperature range from 50 to 10°C.

Known a number of structural steels intended for the manufacture of such products.

For example, the steel GS (OST 14-21-77) of the following composition, wt.%:

Carbon 0,32-0,40

Silicon 0,40-0,70

Manganese 1,50-1,80

Chromium not more than 0,25

Nickel is not more than 0,25

Copper not more than 0.20

Sulfur does not exceed 0.035

Phosphorus does not exceed 0.035

Iron Rest.

Steel of such composition is characterized by a relatively low strength properties.

Also known steel G technical specifications 14-104-168-97, contains, wt%:

Carbon 0,30-0,35

Silicon 0,17-0,37

Manganese 1,20-1,50

Chrome does not exceed 0.30

Nickel : not more than 0.20

Copper does not exceed 0.30

Sulfur does not exceed 0.035

Phosphorus does not exceed 0.035

Iron Rest.

However, this steel does not have a sufficiently high rate mechanical properties and cold resistance.

Closest to the claimed invention to the technical essence and the achieved result is taken as the prototype of the steel GS technical specifications 14-104-65-86, contains, wt%:

Carbon 0,33-0,41

Silicon 0,40-0,70

Manganese 1,30-1,60

Chromium not more than 0,25

Nickel is not more than 0,25

Copper does not exceed 0.30

Sulfur does not exceed 0.035

Phosphorus does not exceed 0.035

Iron Rest.

The disadvantages of the known steels are low in impact strength in combination with insufficiently high performance strength properties that affect the operational characteristics of the steel.

The task of the invention is the improvement in impact strength in combination with the increase in strength properties of the metal in the hot rolled condition, increased structural strength and operational characteristics of the tubing.

To achieve this goal, we offer steel containing carbon, silicon, manganese and iron, further comprises aluminum, titanium, molybdenum and niobium in the following ratio, wt.%:

Carbon 0,42-0,54

Silicon 0,15-0,50

Manganese 0,90-1,50

Niobium 0,01-0,08

Molybdenum 0,06-0,20

Aluminum from 0.005 to 0.060

Titanium 0,010-0,045

Iron Rest.

As impurities in steel allowed sulfur and phosphorus in the range 0.001-0,045% each, as well as chromium, Nickel and copper up to 0.30% of each and nitrogen to 0,012%.

The selected ratio of the components is determined by the following factors.

Carbon is the main chemical element in steel, which is about what defines its strength and performance. The lower limit of 0.42% is limited by the necessity of obtaining the required combination of strength properties of metal after refining in the manufacture of seamless hot-rolled pipes. The upper limit of carbon 0,54% is limited by the need to ensure high viscous properties.

The manganese is in the range of 0.90-1.40 per cent provides the desired combination of strength and ductile properties by increasing the influence of niobium and molybdenum on the stability of supercooled austenite.

Niobium is the lower limit of the content of niobium to 0.01%is the limit below which the niobium does not have a tangible positive impact on the grinding of grain and gladstonos steel; if the content of niobium more than 0.08%, there is a excessive-density phase of the element, leading to reduction of ductility of steel and impact properties.

The molybdenum content in the range 0,06-0,20% allows to obtain the required combination of strength and viscous properties of the metal due to the efficient grinding of grain. The increase in the content of molybdenum over 0,20% leads to a significant increase in the hardenability of steel and appear in the result of large thermal stresses of the metal pipes in metallurgical repartition at the production stage; when the mass fraction of molybdenum less than 0.06% of its influence is negligible.

Aluminum is RA is Kislyuk and the modifying element. In addition, it binds to nitrogen in the nitride. When the aluminum content of less than 0,005% its impact slowly, the steel has a low mechanical properties. Increasing the aluminum content over to 0.060% leads to raznozernistoy microstructure of steel, which, in turn, leads to a significant reduction in ductility and toughness of the metal.

Titanium - ties of nitrogen in steel, and within 0,010-0,045% provides sufficient diazotization liquid metal before the introduction of niobium in the steel, thus achieving the required amount of niobium in the form of carbides in the solid solution.

The steel of the proposed structure provides a combination of strength properties and cold resistance of the metal tube workpiece (PL. 1 and 2). Analysis of technical solutions in the area of study allows to draw a conclusion about the absence of these symptoms that are similar to the features of the claimed solution, and to recognize his invention, because it is new, meets the criterion of inventive step and is industrially applicable.

Example. Steel was smelted in the electric furnace. After the release of the metal from the furnace was producing his treatment in the ladle and poured into ingot molds. Alloying steel with molybdenum was carried out in the process of steel smelting in the furnace by entering ferromolybdenum in the number of 1.30-1.70 kg/t of steel. When out-of-furnace processing to the above spent the final deoxidation of metal, its refining, homogenizing the neutral gas blowing and modifying the processing of the silicocalcium. In the smelting and secondary treatment received steel of the following composition, wt.%: With - 0,48%, Mn - 1,25%, Si - 0,34%, Nb - 0,04%, Mo - 0,09%, S - 0,004%, P - 0,010%, iron - rest. The steel is further contained Cr - 0,16%, Cu - 0,11%, Ni - 0,16%, Al - 0,018% and Ti - 0,015%.

Steel casting molds carried out at a temperature 1540-1545°C. the Ingot was kept in the molds for at least 3 hours, stripped and subjected to the austenization are determined at a temperature of 1200-1300°C for 4 hours. After austenization are determined produced heating of the ingots to a temperature 1250-1280°With, rolling them on the blooming and cooling blooms. Then made the isothermal speed bumps at a temperature of 700°C for 48 hours, heating to 1250-1290°and pre-strain for 9 passages in the reverse mode and the final deformation for 7 passes with the temperature of the end of the deformation 850-900°to get rolled.

After the end of the deformation process was carried out by the final cooling of rolled billets to the ambient temperature. Testing of mechanical properties of samples and toughness at temperatures down to 0, minus 20 and minus 40°showed that the proposed steel has a higher strength and viscous characteristics that provide the t improved performance and reliability of pump-compressor pipes and couplings to them in terms of simultaneous exposure to static and cyclic loads wide temperature range operation.

Structural steel containing carbon, silicon, manganese and iron, characterized in that it additionally contains aluminum, titanium, molybdenum and niobium in the following ratio, wt.%:

Carbon 0,42-0,54

Silicon 0,15-0,50

Manganese 0,90-1,50

Sulfur 0,001-0,045

Phosphorus 0,001-0,045

Nitrogen Not exceeding 0,012

Chrome does Not exceed 0.30

Nickel does Not exceed 0.30

Copper does Not exceed 0.30

Niobium 0,01-0,08

Molybdenum 0,06-0,20

Aluminum from 0.005 to 0.060

Titanium 0,010-0,045

Iron Rest



 

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SUBSTANCE: claimed steel contains (mass %): carbon 0.21-0.40; silicium 0.60-1.50; manganese 0.20-0.60; chromium 4.00-6.00; nickel 0.20-2.00; vanadium 0.30-0.60; titanium 0.01-0.50; tellurium 0.001-0.020; aluminum 0.01-0.50; molybdenum or molybdenum and tungsten in total 1.00-2.00; and balance: iron. Molybdenum content in steel is not less than 0.40 mass %, and one mass part of molybdenum is equivalent to two mass parts of tungsten. Steel may additionally contain (mass %) calcium up to 0.30; zirconium up to 0.35; cerium up to 0.35, and boron up to 0.015. Content of inevitable impurities in claimed steel is limited: e.g. (mass %) sulfur, phosphorous and copper each not more than 0.040; lead, arsenic, and antimony each not more than 0.010.

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FIELD: metallurgy; production of important rolled stock for oil-well tubing of increased service life.

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1 ex

FIELD: metallurgy; high-titanium-bearing foundry alloy production.

SUBSTANCE: the invention is dealt with the field of metallurgy, in particular, with production of the foundry alloy containing mainly titanium and also a small amount of other useful metals reduced from oxides of a charge together with the basic components of a foundry alloy. The method includes the following stages: after melting-down of the first portion of the charge representing an ilmenite concentrate formed on the rotating melt of the high-titanium-bearing foundry alloy and reduction by titanium and silicon of a part of oxides from the melted portion of ilmenite they use aluminum to reduce all oxides in a cinder melt. The obtained slag is added with the first portion of calcium oxide in the amount ensuring fluidity of the cinder. The second portion of the charge is introduced in the melt in the amount corresponding to the possibility of to reduce oxides by titanium. The produced titanium oxide is merged with the earlier produced cinder. A determined part of the produced melt in conditions of its rotation is poured out through a side tap hole. Using aluminum reduce titanium oxide from the merged cinder and the reduced titanium merge with the rest metal melt. In the formed final cinder enter the second portion of calcium oxide. A part of the produced foundry alloy is poured out through a side tap hole. Then a final cinder is also poured out and they feed a new portion of ilmenite onto the residue of the foundry alloy. The invention allows to reduce at least twice the power input used for reprocessing of the ilmenite concentrate, as in the process of reduction of the metals from oxides there are no endothermic reactions but exothermic reactions; to use ilmenite concentrates with a share of titanium oxide up to 45% and a strong metal reductant - aluminum, and also to realize a progressive technology of the liquid-phase reduction of metals from oxides in conditions of rotation of the melt by an electromagnetic field.

EFFECT: the invention allows to reduce at least twice the power input used for reprocessing of the ilmenite concentrate, to use ilmenite concentrates with a share of titanium oxide up to 45% and a strong metal reductant - aluminum, to realize a progressive technology of the liquid-phase reduction of metals from oxides.

5 cl, 1 ex, 1 dwg

FIELD: ferrous metallurgy.

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EFFECT: ensured optimal conditions for cold die forging of high-strength geometrically complex fastening members and simultaneously ensured improved characteristics of in-process plasticity and low level of stray hardening.

FIELD: ferrous metallurgy.

SUBSTANCE: invention provides round-profiled iron smelted from alloyed steel composed of, wt %: carbon 0.06-0.11, manganese 0.30-0.9, silicon 0.001-0.15, boron 0.0005-0.0050, vanadium 0.005-0.08, aluminum 0.02-0.06, titanium 0.01-0.04, sulfur 0.005-0.020, nitrogen 0.005-0.015, calcium 0.001-0.010, iron and unavoidable impurities - the balance. When following relationships are fulfilled: Ti/48+Al/27-N/14 ≥ 0.6 x 10-3; Mn+5.0C ≥ 0.80; Ca/S ≥ 0.065, rolled iron has following characteristics: maximum degree of pollution with nonmetal inclusions, in particular sulfides, oxides, silicates, and nitrides, does not exceed 3 points for each type of inclusions; longitudinally uniform spheroidized structure composed of at least 60% grainy perlite; effective grain size 5-10 points; diameter 10-16 mm; carbon-free layer not exceeding 1.0% of diameter; cold setting value at least 1/3 height; throughout hardenability in circles up to 16 mm in diameter; point of maximum load not higher than 500 MPa; relative elongation at least 22%; and relative contraction at least 70%.

EFFECT: ensured optimal conditions for cold die forging of high-strength geometrically complex fastening members and simultaneously improved steel hardenability characteristics.

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The invention relates to the field of metallurgy, in particular to the production of long-rolled products of boron steel for cold massive forming of high-strength fasteners particularly complex form
The invention relates to the field of metallurgy, in particular to the production of long-rolled products of boron steel for cold massive forming of high-strength fasteners particularly complex form

FIELD: ferrous metallurgy.

SUBSTANCE: invention provides round-profiled iron smelted from alloyed steel composed of, wt %: carbon 0.06-0.11, manganese 0.30-0.9, silicon 0.001-0.15, boron 0.0005-0.0050, vanadium 0.005-0.08, aluminum 0.02-0.06, titanium 0.01-0.04, sulfur 0.005-0.020, nitrogen 0.005-0.015, calcium 0.001-0.010, iron and unavoidable impurities - the balance. When following relationships are fulfilled: Ti/48+Al/27-N/14 ≥ 0.6 x 10-3; Mn+5.0C ≥ 0.80; Ca/S ≥ 0.065, rolled iron has following characteristics: maximum degree of pollution with nonmetal inclusions, in particular sulfides, oxides, silicates, and nitrides, does not exceed 3 points for each type of inclusions; longitudinally uniform spheroidized structure composed of at least 60% grainy perlite; effective grain size 5-10 points; diameter 10-16 mm; carbon-free layer not exceeding 1.0% of diameter; cold setting value at least 1/3 height; throughout hardenability in circles up to 16 mm in diameter; point of maximum load not higher than 500 MPa; relative elongation at least 22%; and relative contraction at least 70%.

EFFECT: ensured optimal conditions for cold die forging of high-strength geometrically complex fastening members and simultaneously improved steel hardenability characteristics.

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