Method of production of merchant shapes in form of bars from medium-carbon micro-alloyed steel

FIELD: metallurgy; production of round bars used for manufacture of shock absorber rods.

SUBSTANCE: proposed method includes melting steel in electric furnace, off-furnace treatment, pouring into ingot molds at protection of jet, hot rolling of ingot, thus obtaining billet followed by rolling, controlled cooling and winding bars in bundles, calibration of bars at deformation degree of 20-25%, unwinding of bars, cutting and straightening and special treatment of surface. Steel contains the following components, mass-%: carbon, 0.40-0.52; manganese, 0.40-0.95; silicon, 0.17-0.37; chromium,, 0.01-0.25; sulfur, 0.020-0.045; vanadium, 0.005-0.020; aluminum, 0.03-0.050; calcium, 0.001-0.010; nitrogen, 0.005-0.015; nickel, up to 0.25; copper, no more than 0.25; molybdenum, no more than 0.10; arsenic, no more than 0.08; phosphorus, no more than 0.030; the remainder being iron and unavoidable admixtures. Calcium-to-sulfur ratio is ≥0.065; hot rolling of merchant shaped is completed at temperature of 1000-1050°C followed by fast cooling to 880-900°C and cooling in air to 300°C. Length of bars from bundle of hot-rolled shapes reaches 6 m at accuracy of cutting of ±5 mm. Finishing of shapes includes trimming, check of surfaces for flaws and ultrasonic monitoring of internal defects, selective dressing.

EFFECT: enhanced machinability of merchant shapes; enhanced ductility and toughness.

1 ex

 

The invention relates to the field of metallurgy, in particular to the production of long-rolled steel with special surface finish, round, bars and rods of medium-carbon, micro steel high machinability, used for the manufacture of the absorber rods.

Known structural steel, containing (wt.%): carbon range 0.38-0.47, the manganese 0,8-1,2, silicon 0,17-0,37, vanadium 0,08-0,18, boron 0,001-0,005, nitrogen from 0.005 to 0.025, sulfur being 0.036-0,080, calcium 0,001-0,010, the rest provided that the ratio of manganese to calcium is 100-1100 (USSR Author's certificate SU 1689424 A1, With 22 38/60 from 07.11.1989,, bull. No. 41). The disadvantage of this steel is relatively high nitrogen content and the absence in the composition of the elements protect the boron from binding in the nitrides, which in some cases will not allow to achieve the claimed by the authors of the effect for improving the hardenability characteristics.

Known structural steel, containing (wt.%): carbon 0,42-0,50, silicon 0,17-0,37, manganese from 0.50 to 0.80, sulfur is not more than 0,040, phosphorus does not exceed 0.035, the rest of the iron. Impurities: chromium - not more than 0,25%, Nickel not exceed 0.30%, arsenic - not more than 0.08%, nitrogen not more than 0,008%, copper not exceed 0.30% (Marochnik steels and alloys, edited by A.s.zubchenko, M., engineering, 2003, p.102). The disadvantage of this steel is an ad hoc sulfur content, which will lead to significant is the deterioration of the characteristics of cutting, to reduce the resistance of the cutting tool, the increasing pressure on the tool when the lower sulfur level in the proposed interval - i.e. less than 0.012%. Also among the disadvantages include the absence in it of reactive elements, such as calcium, which will contribute to the presence of steel elongated sulfide inclusions, and, as a consequence, the high anisotropy of the mechanical properties of hot-rolled.

A known method for the production of long products, including boron steel smelting, production of metal casting, hot rolling, cooling...(Patent DE 3434744 A1, 03.04.1986, With 21 D 8/06, claims ).

A known method for the production of long steel products, including steel smelting in the electric furnace, the production of metal, secondary treatment, continuous casting, hot rolling of continuously cast billets, cooling (EN 2156313 C1 21 D 8/02, 20.09.2000,)

The technical result of the invention is to improve characteristics machinability, with the concurrent increase hardenability characteristics and ensuring end-to-end hardenability rolled diameter up to 23 mm

To achieve a technical result, the method of production all rolled into bars, calibrated round, of medium-carbon steel includes steel smelting in the electric furnace, nauchnoy processing of obtaining steel in the following ratio of components, wt.%:

carbon0,40-0,52
manganese0,40-0,95
silicon0,17-0,37
chrome0,01-0,25
sulfur0,020-0,045
vanadiumof 0,005 0,020
aluminum0,03-0,050
calcium0,001-0,010
nitrogen0,005-0,015
Nickelto 0.25
coppernot more than 0,25
molybdenumnot more than 0.10
arsenicnot more than 0.08
phosphorusno more than 0,030
iron and inevitable impuritiesthe rest,

when performing ratio: calcium/sulfur≥0,065, steel casting molds with stream protection with argon, hot rolling the ingot to obtain billets, hot rolling of billets long products, which finished at a temperature of 1000-1050°, accelerated cooling of rolled up 880-900°C, followed by cooling to 300°C, calibrated with deformation rate of 20-25%, the winding rental in riots, uncoiling, cutting with getting the car up to 6 meters with precision cutting ±5 mm, finish rolled by editing, control the behavior of the displacement defects, ultrasonic inspection of internal defects and selective grinding machine.

Given the combination of alloying elements allow you to get in the proposed steel bars hot-rolled round with a diameter up to 25 mm), favorable lamellar structure with globular sandwich inclusions, which provides, on the one hand, high characteristics of cutting even a broad incisors when the transverse axis of the cutting tool, on the other hand is a favorable combination of strength and ductility.

Carbon is introduced into the composition of this steel to provide the required level of strength and hardenability. The upper limit of carbon content (0.52%) due to the need to ensure the required level of ductility of steel, and the bottom, respectively 0.40% - providing the required level of strength and hardenability of the steel.

Carbonitrides element vanadium is introduced into the composition of this steel to ensure a fine, uniform grain structure, which will increase as the level of its strength, and to provide a given level of ductility. While vanadium manages the processes in the lower part of the austenitic region and microtecnica temperature range (determines the tendency to grain growth of austenite, stabilizes when ructure during thermomechanical processing, raises the temperature of recrystallization and, consequently, affects the character γ-α- transformation. Vanadium also contributes to hardening of the steel during thermolysine. The upper limit of the content of vanadium - 0,02%, due to the need to ensure the required level of ductility of steel, and the bottom, respectively 0.005% by providing the required strength level of the steel.

Manganese and chromium are used on the one hand, as a solid solution hardeners, on the other hand, as elements significantly increases the stability of the supercooled austenite steel. The upper levels of manganese - 0.95% chromium, 0.25% is determined by the need to ensure the required level of ductility of steel, and the lower, manganese - 0.40% and 0.01% chromium, respectively, by the need to provide an appropriate level of strength and hardenability of the steel.

Silicon belongs to territooriumil elements. The lower limit for silicon-0.17% caused by the deoxidation of steel. The silicon content higher 0.37% will adversely affect the characteristics of ductility of steel.

Sulfur determines the level of ductility of steel. The upper limit (0.040%) due to the necessity of obtaining a given level of ductility and toughness of steel, and. the lower limit (0.020%) - questions-tech production, as well as providing a given the level of machinability of the steel.

Aluminum is used as a deoxidizer of steel and the element capable of forming a fine, uniform grain structure. The upper limit (0.050%) due to the necessity of obtaining a given level of ductility and toughness of steel, and the lower limit (0.030%) - questions-tech production, as well as to ensure uniform grain structure of the steel.

Calcium is an element modifying nonmetallic inclusions. The upper limit (0.010%) as in the case of sulfur caused by the necessity of obtaining a given level of ductility and toughness of steel, and the lower (0.001%) limit issues-tech production.

Nitrogen promotes the formation of nitrides in the steel. The upper limit of soderzhaniya nitrogen - 0.015% due to the necessity of obtaining a given level of ductility and toughness of steel, and the lower limit is 0.005% issues technology of production.

The ratio of calcium/sulfur≥0.065% defines the conditions for the formation of globular inclusions (sulphides). If this ratio, the globular sulfides, otherwise in steel are elongated sulfides, which increases the anisotropy of the properties of steel and worsens the ratio of the strength-toughness. particularly in the transverse direction of the car.

Comparative analysis of the prototype allows you to make yvod, that the claimed composition differs from the known.

Therefore, the claimed set of characteristics meets the criterion of "substantial differences".

An example of implementation of layer method:

Smelting of the investigated steel (chemical composition in wt.%: carbon - 0.48, manganese - 0.72, silicon - 0.32, chrome - 0.10, vanadium - 0.01, sulfur - 0,034, aluminum-0.037, calcium - 0.0025, nitrogen - 0.010 conducted produced in shaft furnace "Fuchs". Used blending melting liquid cast iron up to 40% of the total volume of the mixture. Oxidative period included a high rate of oxidation of carbon within 0,05-0,07%/min electric mode involved the shutting down of the furnace when the carbon content of 0.2-0.4 percent above the lower limit specified, dodavku the carbon produced without arcing. The temperature of the discharge from the furnace 1640-1680°C. Enter ferroalloys, steel treatment to remove non-metallic inclusions was performed on the ladle furnace equipped with an electric heating system or hinotori. The temperature of the steel before casting on 60°C above the liquidus temperature of the brand. Casting was carried out in extended to the top of the mold. The mass of the ingot a 7.85 so To provide a given nitrogen content in the casting produced of stream protection metal with argon through a special ring device. Heating of the ingots in the blooming plant produced in rivers is operativnyh wells before the temperature started rolling 1250-1270° C. Rolling ingots was carried out on the blooming mill (mill 1300) and then on a continuous billet mill on the billet cross section of 100×100 mm For removing the formed during heating of ingots de-carbonized layer preform was subjected to abrasive blasting." Then made hot rolling the resulting workpiece on a wire mill 150 or small-section mill 250 in diameters from 5.5 to 23 mm in coils. To ensure the value of de-carbonized layer is not more than 1% of the diameter of the limited rate of billets from the furnace is not less than 100 t/h for 150 mill and not less than 56 tons/hour for mill 2.50. The onset temperature rolling of billets 1220-1240° (C) to 250 mill and 1270-1290° (C) to 150 mill. Hot rolling of the rolled finish at a temperature of 1000-1050°this temperature is rapidly cooled to 880-900°and then in air to 300°C. Subjecting car calibration with deformation rate of 20-25%, producing winding rental in riots. After unwinding rolled lead cutting of rental with receiving rods of length up to 6 meters with precision cutting ±5 mm Finish rolled carry out flow in the following sequence: edit, control of surface defects, ultrasonic inspection of internal defects, selective abrasive cleaning.

In the hot rolling and subsequent finishing of the surface of the obtained rolled 022,5 mm, length of the OI - 5900 mm, the curvature of the bars - not more than 0.7 mm/m lamellar Structure of pearlite, bezplatny layer depth of 0.05 mm, the score of the actual grain - 7, the hardness of the workpiece 229-241 HB, ultimate strength, 680 MPa, an elongation of 9%, relative narrowing 42%

Ratio

calcium/sulfur= 0.074 calcium - 0.0025%, sulfur - 0,034%

The introduction of the proposed method of production of long-rolled products from medium carbon steel high machinability, providing a two-layer sandwich of non-metallic inclusions, guaranteeing, on the one hand, ensuring high performance cutting, on the other hand favorable ratio between strength ductility and toughness of steel.

Method of manufacturing calibrated round rolled in the bars of medium carbon steel including steel smelting in the electric furnace, secondary treatment with obtaining steel in the following ratio, wt.%:

Carbon0,40-0,52
Manganese0,40-0,95
Silicon0,17-0,37
Chrome0,01-0,25
Sulfur0,020-0,045
Vanadium0,005-0,02
Aluminum 0,03-0,05
Calcium0,001-0,010
Nitrogen0,005-0,015
NickelTo 0.25
CopperNot more than 0,25
MolybdenumNot more than 0.10
ArsenicNot more than 0.08
PhosphorusNo more than 0,030
Iron and
inevitable impuritiesRest

when executing the ratio of calcium:sulfur≥0,065, steel casting molds with stream protection with argon, hot rolling the ingot to obtain billets, hot rolling of billets long products, which finished at a temperature of 1000-1050°, accelerated cooling of rolled up 880-900°C, followed by cooling to 300°C, calibrated with deformation rate of 20-25%, the winding rental in riots, uncoiling, cutting with getting the car up to 6 m with a precision cutting ± 5 mm, finish rolled by editing, control of surface defects, ultrasonic inspection of internal defects and selective grinding machine.



 

Same patents:

FIELD: metallurgy; production of merchant shapes for manufacture of spherical pins, end-pieces of rods and spherical supports for automobile suspensions.

SUBSTANCE: merchant shapes are molten from steel containing the following components, mass-%: carbon, 0.35-0.42; manganese, 0.50-0.80; silicon, 0.17-0.37; chromium, 0.80-1.10; sulfur, 0.020-0.040; vanadium, 0.005-0.020; calcium, 0.001-0.010; oxygen, 0.001-0.015; nickel, up to 0.25; copper, no more than 0.25; molybdenum, no more than 0.10; arsenic, no more than 0.08; nitrogen, no more than 0.015; the remainder being iron and unavoidable admixtures at oxygen-to-calcium ratio equal to 1-4.5 and calcium-to-sulfur ratio ≥0.065. Proposed merchant shapes contains nonmetallic inclusions of sulfide having double-layer structure; maximum contamination with nonmetallic inclusions pertaining to sulfides, oxides, silicates and nitrides does not exceed 3 points; it contains also structure consisting of 80% of granular pearlite; size of actual grain is 5-10 points at diameter ranging from 10 to 30 mm; provision is made for decarbonized layer not exceeding 1.5% of diameter, magnitude of cold upsetting is no less than 1/3 of height, rupture strength does not exceed 600 Mpa; relative elongation is no less than 18% and relative reduction in area is no less than 60%.

EFFECT: enhanced machinability at full hardenability of shapes up to 30 mm in diameter; retaining of technological ductility of steel.

1 ex

Low-alloyed steel // 2283362

FIELD: metallurgy; making of low-alloy steels for manufacture of articles operating in aggressive media containing hydrogen sulfide and carbon dioxide.

SUBSTANCE: proposed low-alloyed steel contains the following components, mass-%: carbon, 0.05-0.15; manganese, 0.40-0.65; chromium, 0.50-0.80; silicon, 0.30-0.80; vanadium, 0.04-0.09; aluminum, 0.02-0.05; the remainder being iron and admixtures. Content of admixtures is limited as follows, mass-%: nitrogen, no more than 0.008; nickel, no more than 0.30; copper, no more than 0.25; hydrogen, no more than 0.0002; total calcium/sulfur ratio shall be no less than 1. In particular case, proposed steel may contain titanium and niobium; total amount of vanadium, titanium and niobium shall not exceed 0.15 mass-%. Proposed steel may be used for manufacture of pipes and joints for handling aggressive media, watery oil and formation water in particular characterized by high degree of mineralization and containing H2S and CO2.

EFFECT: enhanced strength characteristics and corrosion resistance.

2 cl, 4 tbl

Rail steel // 2259416

FIELD: ferrous metallurgy; production of rail steel.

SUBSTANCE: the invention is pertaining to the field of ferrous metallurgy, in particular, to production of steel for manufacture of railway rails. The offered rail steel contains its components in the following ratio (in mass %): Carbon - 0.83-0.5; manganese - 0.6-1.1; silicon - 0.3-0.7; vanadium - 0.08-0.15; aluminum - no more than 0.005; nitrogen - 0.012-0.02; calcium -0.0005-0.005; chromium - 0.05-0.5; one of the devices sampled from a group including zirconium and REM, namely, zirconium -0.0005-0.005; REM - 0.0005-0.005; molybdenum - 0.11-0.3; nickel - 0.05-0.3, iron and impurities - the rest. The technical result of the invention is an increased complex of mechanical properties, firmness of steel and its resistance to brittle fracture, which improves operational stability of the rails. Out of the steel of a stated composition it is possible to manufacture the rails hardened both in oil and in a compressed air with a troostite structure.

EFFECT: the invention ensures an increased complex of the rail steel mechanical properties, firmness of the steel, its resistance to brittle fracture and production of rails with a troostite structure.

2 tbl

The invention relates to welding and for the composition of welding wire for welding and surfacing of products from high-carbon steels operating at high alternating loads, and can be used mainly when restoring components and parts railroad rolling stock

Steel // 2232201
The invention relates to ferrous metallurgy, in particular to find the composition of the steel used in the manufacture of knives designed for cutting scrap

Steel // 2224042
The invention relates to ferrous metallurgy, in particular to research of high-strength steels for bolts rails

Structural steel // 2217519
The invention relates to structural alloyed steels for the manufacture of machine parts and mechanisms and can be used in engineering, transport, automotive, road machinery and other fields, as well as in defense technique for the manufacture of ammunition
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Bearing steel // 2113533
The invention relates to the field of metallurgy and can be used in the manufacture of bearing parts that operate when exposed to aggressive environments

FIELD: metallurgy; production of merchant shapes for manufacture of spherical pins, end-pieces of rods and spherical supports for automobile suspensions.

SUBSTANCE: merchant shapes are molten from steel containing the following components, mass-%: carbon, 0.35-0.42; manganese, 0.50-0.80; silicon, 0.17-0.37; chromium, 0.80-1.10; sulfur, 0.020-0.040; vanadium, 0.005-0.020; calcium, 0.001-0.010; oxygen, 0.001-0.015; nickel, up to 0.25; copper, no more than 0.25; molybdenum, no more than 0.10; arsenic, no more than 0.08; nitrogen, no more than 0.015; the remainder being iron and unavoidable admixtures at oxygen-to-calcium ratio equal to 1-4.5 and calcium-to-sulfur ratio ≥0.065. Proposed merchant shapes contains nonmetallic inclusions of sulfide having double-layer structure; maximum contamination with nonmetallic inclusions pertaining to sulfides, oxides, silicates and nitrides does not exceed 3 points; it contains also structure consisting of 80% of granular pearlite; size of actual grain is 5-10 points at diameter ranging from 10 to 30 mm; provision is made for decarbonized layer not exceeding 1.5% of diameter, magnitude of cold upsetting is no less than 1/3 of height, rupture strength does not exceed 600 Mpa; relative elongation is no less than 18% and relative reduction in area is no less than 60%.

EFFECT: enhanced machinability at full hardenability of shapes up to 30 mm in diameter; retaining of technological ductility of steel.

1 ex

FIELD: metallurgy; production of round calibrated bars from medium-carbon steel of high machinability for manufacture of shock absorber rods.

SUBSTANCE: proposed method includes making steel in electric-arc furnace, off-furnace treatment, micro-alloying with sulfur, continuous teeming at protection of jet with argon, hot rolling of continuously cast billet making use of mechanical heat treatment modes, hot calibration and winding merchant shape in bundles, unwinding bars, cutting and straightening bars. Steel contains the following components, mass-%: carbon, 0.42-0.50; manganese, 0.50-0.80; silicon, 0.17-0.37; sulfur, 0.020-0.040; phosphorus, 0.001-0.030; aluminum, 0.03-0.05; calcium, 0.0010.010; oxygen, 0.001-0.015; chromium, no more than 0.25%; nickel, up to 0.35%; copper, no more than 0.25%; molybdenum, no more than 0.10%; arsenic, no more than 0.08%; nitrogen, no more than 0.015%. The remainder being iron and unavoidable admixtures. Ratio of oxygen and calcium content is determined by the following ratio: oxygen/calcium =1-4.5 and calcium-sulfur ≥0.065. At tapping from melting unit, metal is subjected to deep deoxidation, alloying with silicon, manganese, chromium etc. After bringing the chemical composition of metal to specified level pertaining to all elements, but for aluminum and sulfur, metal and slag are subjected to repeated oxidation with gaseous oxygen or oxidized pellets. Then aluminum is added followed by treatment with calcium and alloying with sulfur.

EFFECT: enhanced conditions for machining articles made from this steel; improved ductility and toughness characteristics of steel.

1 ex

FIELD: metallurgy; production of merchant shapes from medium-carbon steel at high machinability for manufacture of shock absorber rods for automobiles.

SUBSTANCE: proposed method enhances machinability at optimum ratio of strength, ductility and plasticity, minimum level of anisotropy at simultaneous improved characteristics of hardenability to level of through hardenability of rods to 30 mm. Proposed bars are made from medium-carbon steels containing carbon and alloying elements and possessing preset parameters of metallurgical quality, structure, mechanical properties, hardenability and machinability; medium-carbon steel contains the following components, mass-%: carbon, 0.42-0.50; manganese, 0.50-0.80; silicon, 0.17-0.37; sulfur, 0.020-0.040; phosphorus, 0.001-0.030; aluminum, 0.03-0.05; calcium, 0.001-0.010; oxygen, 0.001-0.015; chromium, no more than 0.25; nickel, no more than 0.025; copper, no more than 0.25; molybdenum, no more than 0.10; arsenic, no more than0.08; nitrogen, no more than 0.015; the remainder being iron and unavoidable admixtures. Ratio of oxygen and calcium , as well as calcium and sulfur is determined by the following dependances: oxygen/calcium= 1-4.5 and calcium/sulfur≥0.065. Nonmetallic inclusions of sulfides have double-layer structure: sulfide with oxide envelope; curvature of bars does not exceed 1.0 mm/m; rolled bars have plastic ferrite-pearlite structure at actual size of grain of 5-8; diameter of bars ranges from 10 to 30 mm; decarbonized layer is no more than 1.5% of diameter; hardness of billet is 229-255; rupture strength no less than 640 Mpa; relative elongation no less than 6% and relative reduction no less than 30%.

EFFECT: improved machinability characteristics at optimum ductility and strength; improved hardenability characteristics.

1 ex

FIELD: metallurgy, namely production of rolled bars.

SUBSTANCE: round rolled bar is made of steel containing, mass %: carbon, 0.17 -0.23; manganese, 0.65 -0.95; silicon, 0.17 - 0.37; chrome, 0.35 - 0.65; nickel, 0.40 - 0.75; molybdenum, 0.15 -0.25; sulfur, 0.020 - 0.040; phosphorus, 0.001 - 0.010; oxygen, 0.001 -0.015; copper, no more than 0.25; arsenic, no more than 0.08; nitrogen, no more than 0.015; iron and inevitable impurities, the balance; at relations oxygen/calcium = 1.45; calcium/sulfur ≥ 0.065. Rolled bar contains double-layer structure sulfide - sulfide with oxide envelope and it has hardness after quenching in depth 6 mm 32 - 40 HRc, size of real grain 5 - 10 points, diameter - up to 50 mm. Rolled bar has no decarbonized layer. After quenching and tempering rolled bar is characterized by temporary tensile strength, 1180 - 1520 MPa; limit yield, no less than 930 MPa; percentage elongation, no less than 7%; percentage tapering, no less than 59%.

EFFECT: improved cutting capability, enhanced hardenability at keeping high technological ductility.

1 ex

FIELD: metallurgy; methods of production of the circular bars.

SUBSTANCE: the invention is pertaining to the field of metallurgy, in particular, to production of circular hot-rolled hot-calibrated and turned bars made out of the medium alloy steel of the heightened cutability used for manufacture of the high-loaded pinion gears of the car gearbox. The technical result of the invention is production of the structure of the bar ensuring the rational cutting conditions, which will allow to provide the guarantied level of the consuming properties of the pinion gears of the car gearbox. The method of production of the circular bar made out of the medium alloy steel includes: smelting of the steel in the electric furnace, out-of-furnace treatment of the steel in the ladle with a doping, a reduction and blowing by argon, the steel degassing treatment, the continuous steel casting, the hot rolling of the continuous bars with usage of modes of the thermomechanical treatment. According to the invention after the steel degassing conduct the repeated ladle metal reduction by the oxygenated pellets with the subsequent addition of aluminum, sulfur and produce the steel at the following ratio of the components(in mass %): carbon - 0.17-0.23; manganese - 0.65-0.95; silicon - 0.17-0.37; chromium - 0.35-0.65; nickel - 0.40-0.75; molybdenum - 0.15-0.25; sulfur - 0.020-0.040; phosphor - 0.001-0.035; niobium - 0.005-0.02; vanadium - 0.005-0.08; calcium - 0.001-0.010; oxygen - 0.001-0.015; copper - no more than 0.25; arsenic - no more than 0.008; nitrogen - no more than 0.015; iron and the imminent impurities - the rest; at realization of the following ratios: oxygen/calcium = l÷4.5 and calcium/sulfur ≥ 0.065. After the hot rolling realize the finish of the bars including the straightening, monitoring of the surface defects, the selective abrasive cleaning, the whole-size continuous abrasive grinding, turning of the circular bars, reeling of the bars in bundles and cutting the bars into billets of up to 6 meters length with the cutting accuracy ±5 mm.

EFFECT: the invention ensures production of the bars with the structure providing the rational cutting conditions, which guaranty the required level of the consuming properties of the car gearbox pinion gears.

FIELD: ferrous industry; production of stainless steel of the martensitic-austenitic class.

SUBSTANCE: the invention is pertaining to the field of ferrous industry, to production of stainless steel of the martensitic-austenitic class intended for manufacture of the high-loaded components working on twisting and bending under a dynamic loading in corrosive acid mediums having a high content of salts of alkaline and alkaline-earth metals, salts of nitrogenous acid and sulfuric acid, ions of chlorine and hydrogen sulfide. The steel contains the following ingredients(in mass %): Carbon - 0.005 - 0.07; silicon - no more than 1.0; manganese - no more than 1.8; chrome - 12.5 - 17.0; nickel - 2.0 - 8.0; molybdenum + 3 · tungsten - 0.05 - 5-4.5; nitrogen - 0.005 - 0.15; boron - 0.0001 - 0.01; at least one the following ingredients: aluminum, titanium, niobium, vanadium - 0.01 - 5.0; iron and impurities - the rest. At that Thus (Mo+3·W)≤(kl-Cr·al), where kl=15.9, a1 = 0.87, and alsoNi=k2-a(Cr+Mo+W), wherek2 = 16.25 ± l.5, a2=0.7 ± 0.l. The method of manufacture of the product provides for ingots casting or blanks continuous casting, rolling and thermal treatment. The technical result of the invention is an increased steel plasticity, its corrosion resistance in hydrosulfuric mediums with a simultaneous increase of stability of the steel mechanical properties.

EFFECT: the invention ensures an increased steel plasticity, corrosion resistance in hydrosulfuric mediums, stability of the steel mechanical properties.

25 cl, 2 tbl, 1 ex

FIELD: ferrous metallurgy; production of the corrosion-resistant steel and products made out of it.

SUBSTANCE: the invention is pertaining to the field of ferrous metallurgy, in particular, to production of the corrosion-resistant stainless steel of the martensitic- austenitic class intended for manufacture of the high-loaded component parts working on torsion and bending under a dynamic loading in corrosive acidic mediums with the high content of salts of alkaline and earth metals, salts of nitrogenous and sulfuric acids, ions of chlorine, hydrogen sulfide. The corrosion-resistant steel contains ingredients in the following ratio (in mass %): Carbon - no more than 0.07; chrome - 12.5-17.0; nickel - 2.0-8.0; molybdenum +3 x tungsten - 0.05-4.5; iron and impurities - the rest. At that (Mo+3·W)≤(k1- Cr·a1), where k1=15.9, a1=0.87, and also Ni=k2-a2 (Cr+Mo+W), wherek2=16.25±l.5, a2=0.7±0.1. The technical result of the invention is an increase of pliability, optimal corrosion resistance and strength in the hydrosulfuric mediums with a simultaneous increase of stability of the steel mechanical properties.

EFFECT: the invention ensures an increase of pliability, optimal corrosion resistance and strength in the hydrosulfuric mediums with a simultaneous increase of stability of the steel mechanical properties.

25 cl, 2 tbl, 1 ex

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

SUBSTANCE: proposed method includes making steel of definite chemical composition in electric furnace, tapping metal from furnace into ladle, treatment of metal in ladle and teeming steel into ingot molds. Alloying with molybdenum is performed by introducing molybdenum-containing materials into furnace in making steel. After teeming, ingots are rolled, cooled and heated for rolling in preset temperature range and are subjected to preliminary and final deformation; process is completed by final cooling of rolled blanks to surrounding temperature.

EFFECT: improved strength characteristics and cold resistance of metal; enhanced reliability of metal products.

1 ex

FIELD: ferrous metallurgy.

SUBSTANCE: invention provides round-profiled iron smelted from medium-carbon high-plasticity steel composed of, wt %: carbon 0.27-0.32, manganese 0.30-0.50, silicon 0.01-0.37, chromium 0.01-0.25, sulfur 0.005-0.020, niobium 0.005-0.02, calcium 0.001-0.010, iron and unavoidable impurities - the balance. When following relationships are fulfilled: 12/C-Mn/0.03 ≥ 20, 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 80% grainy perlite; effective grain size 5-10 points; diameter 10-30 mm; carbon-free layer not exceeding 1.5% diameter; cold setting value at least 1/3 height; point of maximum load not higher than 620 MPa; relative elongation at least 18%; and relative contraction at least 55%.

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 low-carbon steel composed of, wt %: carbon 0.17-0.25, manganese 0.30-0.65, silicon 0.01-0.17, sulfur 0.005-0.020, vanadium 0.005-0.07, niobium 0.005-0.02, calcium 0.001-0.010, iron and unavoidable impurities - the balance. When following relationships are fulfilled: 12/C-Mn/0.02 ≥ 27; 0.46 ≥ 6V+8Nb ≥ 0.22; 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 80% grainy perlite; effective grain size 5-10 points; diameter 10-25 mm; carbon-free layer not exceeding 1.5% of diameter; cold setting value at least 1/3 height; point of maximum load not higher than 550 MPa; relative elongation at least 20%; and relative contraction at least 60%.

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: rolled tube production, namely method for making pilger mill mandrels from heat resistant steel for rolling hot rolled tubes.

SUBSTANCE: method for making mandrels used for rolling hot rolled tubes with large and mean diameters in range 273-550mm comprises steps of casting ingots of hear resistant steel; forging cylindrical solid or hollow blanks, roughly working of them, performing heat treatment and finishing mandrels at forming conicity 1 - 2 mm on length of their working portion while taking into account designed linear expansion coefficient during rolling process; determining diameter size by means of expression δ = dn - Δ/1 + αĚt. One portion of mandrel from lock along length of half of working portion of mandrel is in the form of cone with diameters of cone bases determined form given expression and second portion is in the form of cylinder or truncated cone whose diameters are determined according to next expression

EFFECT: lowered lengthwise thickness difference of tubes.

3 cl, 1 dwg, 1 tbl

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