Structural steel of high hardenability
(57) Abstract:The invention relates to metallurgy, in particular to the development of high-strength structural steel for the manufacture of billets used in cold landing fasteners. The proposed structural steel of high hardenability, containing carbon, manganese, silicon, boron, nitrogen and iron in the following ratio of components, wt. %: carbon 0,10 - 0,20, manganese 0,90 - 1,40, silicon 0,15 - 0,30, molybdenum 0,01 - 0,30, boron 0,0005 - 0,0050, titanium 0.01 to 0.04, nitrogen 0,005 - 0,015, iron rest, provided that the content of the elements satisfies the following relations: and Mn + 5 x Mo > 2,15. The technical result of the invention is to increase the hardenability characteristics and ensuring end-to-end hardenability thermolysine steel up to ø 32 mm 2 table. The invention relates to the field of metallurgy, in particular in the development of high-strength structural steel, intended for the manufacture of billets used in cold landing fasteners.Known structural steel, containing (wt. %): carbon 0.15 - 0.30%, silicon 0.5 - 0.8%, manganese 0.7 - 1.5%, phosphorus 0.02 - 0.10, copper 0.1 - 0.4, boron 0.001 - 0.the actual content of alloying elements, which can lead to instability of the mechanical properties, its low efficiency and insufficient hardenability.Closest to the technical essence and the achieved effect to the proposed steel is a steel containing (wt.%): carbon 0.14 - 0.22%, si 0.10 - 0.37%, mn 1.0 - 1.6%, boron 0.005 - 0.010%, nitrogen 0.015 - 0.03%, the rest is iron .The disadvantages of the known steel lies in the fact that at relatively high content is not taken into account the protection factor of boron from binding in the nitrides that will not allow you to get increased hardenability characteristics.The objective of the invention is to increase the hardenability characteristics and ensuring end-to-end hardenability thermolysine steel up to ø 32 mmThis object is achieved in that the proposed steel containing carbon, manganese, silicon, boron, nitrogen and iron further comprises molybdenum and titanium in the following ratio of components, wt.%:
Carbon - 0,10 - 0,20
Manganese - 0,90 - 1,40
Silicon - 0,15 - 0,30
Molybdenum - 0,01 - 0,30
Bor - 0,0005 - 0,0050
Titanium - 0.01 to 0.04)
Nitrogen - 0,005 - 0,015
Iron - Rest
provided that the content elements odulator 0.20% copper, 0.20%, aluminum up to 0.06%.Given the combination of alloying elements allow you to get in the proposed steel (billet billet with a diameter up to 32 mm), after thermolysine (tempering temperature of not less than 920oC followed by tempering temperature not lower than 500oC) a homogeneous fine structure of martensite leave with a favorable combination of strength and ductility.Carbon is introduced into the composition of this steel to ensure strength and hardenability. The upper limit of carbon content (20%) due to the need to ensure the required level of ductility of steel, and the lower (0,10%) - providing the required strength level of the steel.Manganese and molybdenum are used, on the one hand, as a solid solution hardeners, on the other hand, as elements, greatly increasing the stability of the supercooled austenite and increases the hardenability of steel. The upper level of the contents of these elements (respectively 1.40% Mn, 0.30% Mo) is determined by the need to ensure the required level of ductility of steel, and the lower (0.09% Mn, 0.01% Mo) - the need to ensure the required level of strength and prokalivaem the flax technology deoxidation of steel. The silicon content above 0.30% will adversely affect the characteristics of ductility of steel.Boron contributes to a sharp increase in the hardenability of steel. The upper limit of the content of boron (0.0050%) is determined by considerations of ductility of steel, and the lower (0.0005%) - the need to ensure the required level of hardenability.Titanium is used as a deoxidizer and provides protection boron from binding in the nitrides, which contributes to a sharp increase in the hardenability of steel. So the lower level of the titanium content (0.01%) is determined by the requirement to ensure the hardenability of steel, and the upper level (0.04%) - requirement to provide a given level of ductility of steel.Nitrogen is an element that participates in the formation of carbonitrides, while lower levels (0.005%) is determined by the requirement to provide a given level of strength, and the upper level (0.015%) - requirement to provide a given level of ductility and hardenability.To ensure complete bonding of nitrogen in the nitride type TiN as the result of reactions:
[Ti] + [N] = TiN
requires the following relationship elements , otherwise not provided satnarine determines the conditions of preservation in more than 50% effective boron, that provides the specified characteristics of the hardenability of steel.The ratio Mn + 5 Mo 2.15, on the one hand, defines the conditions that ensure a given level of strength of the steel, on the other hand, determines the level of the base doping, providing a minimum level of hardenability of steel.Comparative analysis of the prototype allows us to conclude that the claimed composition differs from the known introduction of new components of molybdenum and titanium, as well as ratios: Mn + 5 Mo 2.15.Analysis of patent and scientific and technical information not found solutions with the same set of features, which would reach a similar effect - enhancing characteristics of the hardenability of steel.The following are examples of implementation of the invention within the scope of the claims.In experimental conditions in 60 kg open induction furnace smelted 10 heats experienced steel, whose chemical composition is given in table 1. Steel was poured into 3 ingot weighing 17 kg, which are then forged on in the section 70 x 70 mm, Then the in was progulivali on a sheet with a thickness of 14 mm From the sheet made of billet samples of size 14 x 14 x 300 mm, which P>oC with a holding time of 50 minutes and cooled in water. Vacation at a temperature of 630oC with a holding time of 30 minutes. The thickness of the workpiece and the cooling during hardening provided through hardenability blanks.The mechanical characteristics were determined on a tangential samples. Tensile test at room temperature was performed on samples: type I, GOST 1497-84, on the test machine "INSTRON-1185" with registration strain deformation. The loading rate of the sample is 5 mm/min was Determined characteristics of strengthbandof 0.2and viscosity .
Average values were calculated according to the results of the test at least three samples per pixel. The significance of differences of average values of the analyzed values were assessed using student's criterion, calculated as follows:
< / BR>where M1and M2- average values compared; S21and S22the dispersion medium;
t0,kr005(a) - critical value of the student test at a significance level of 0.95 and the number of degrees of freedom.
Characterization of hardenability (critical diameter D50) was performed by the method of mechanical hardening tsilindricheskimi underwent heat treatment in a chamber furnace at the following mode: normalization, 950oC, 1 h, air. Tested on two sample for smelting. Hardening of the samples was carried out with a water jet in a special unit. In connection with the need to prevent oxidation and decarburization of the end of the sample in direct contact with water during hardening, heating the samples in a chamber furnace (without protective atmosphere) was performed in special glasses. The end of the sample was placed on a special graphite plate. The sample was heated in a furnace to a temperature of 950oC. the Duration of heating of the sample to the quenching temperature was 30 - 50 minutes. Deviations from the set temperature quenching did not exceed 5oC. Exposure of the sample at a temperature of quenching after heating was 30 minutes drive Time from the moment of extraction of the sample from the furnace before cooling does not exceed 5 seconds. The sample was kept under running water until completely cooled (about 15 - 20 min). The cooling water temperature was 20 - 5oC.For measuring the hardness along the length of the tempered sample was sosotoyalas two diametrically opposite sites to a depth of 0.5 to 0.1 mm of the Site sosotoyalas with abundant cooling water. The roughness of the ground was rougher 7th grade purity of emoti steel measuring the hardness began at a distance of 1.5 mm from the hardened end face in the axial direction. The first 16 measurements from the end of the sample was performed with an interval of 1.5 mm, and then through 3 mm, if necessary, re-measuring the hardness at the site at which measurements were taken, the area was pereshlifovyvat. The depth of metal removal when re-grinding was 0.1 - 0.2 mm Hardness was determined according to Rockwell (HRC) in accordance with the requirements of GOST 9013. For each pair of points lying at the same distance from the end of the sample at two opposite sites, was estimated average hardness
Mechanical properties are presented in table 2.As can be seen from table 2., we offer steel, in comparison with the known higher hardenability characteristics.Sources of information
1. USSR author's certificate N 901331, C 22 C 38/16, 21.04.1980,2. USSR author's certificate N 462880, C 22 C 39/00, 16.03.1973, (prototype)n Structural steel of high hardenability, containing carbon, manganese, silicon, boron, nitrogen and iron, characterized in that it further comprises molybdenum and titanium in the following ratio, wt.%:
Carbon - 0,10 - 0,20
Manganese - 0,90 - 1,40
Silicon - 0,15 - 0,30
Molybdenum - 0,01 - 0,30
Bor - 0,000 now satisfies the following relationships:
< / BR>Mn + 5 Mo Of 2.15.
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.
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: 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: 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.
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
FIELD: metalwork operating in cold climates at static loads.
SUBSTANCE: proposed iron-based cold-resistant alloy includes the following components, mass-%: titanium, 1-2; carbon, 0.009 max; silicon, 0.1 max; aluminum, 0.003 max; copper, 0.03 max; nickel, 0.2 max; the remainder being iron. Proposed alloy possesses high strength at retained ductility; embrittlement of this alloy at cooling to temperature below minus 78°C is excluded; content of carbon is considerably reduced due to increased content of titanium, thus enhancing resistance to cold.
EFFECT: enhanced efficiency; enhanced cold resistance.
1 dwg, 1 tbl
FIELD: ferrous metallurgy; motor-car industry; production of steels intended for manufacture of items of a complex configuration with the help of cold sheet stamping.
SUBSTANCE: the invention is pertaining to the field of ferrous metallurgy and motor-car industry, in particular, to methods of production of steels intended for manufacture by cold sheet stamping of items of a complex configuration, predominantly details for motor cars. The technical problem is to boost steel stamping, to improve the quality of a surface of a steel strip and hence to improve adhesion of a protective cover. The method includes a steel smelting, casting, hot rolling, strips reeling in rolls, a cold rolling, a recrystallization annealing and a temper rolling. The steel contains components in the following ratio (in mass %): Carbon - 0.002 - 0.008, silicon - 0.005-0.025, manganese - 0.05-0,20, phosphorus - 0.005-0.025, sulfur - 0.003-0.012, aluminum - 0.02-0.07, titanium - 0.02-0.05, niobium - 0.001 0.080, iron and imminent impurities - the rest. The hot rolling is completed at the temperature determined from the ratio: Tf.r≥ 7300 / (3.0-Ig [Nb] [C]) - 253, where Tf.r - temperature of the end of the rolling, °C; [Nb] and [C] - the shares of niobium and carbon in the steel accordingly in mass %, and the recrystallization annealing is carried out in a pusher-type furnace at the temperature assigned depending on the contents of niobium in steel according to the equation: Tan= (750+ 1850 [Nb]) ± 20, where Tan - a temperature of the thermal treatment, °C; [Nb] - the contents of niobium in the steel, in mass %.
EFFECT: the invention allows to boost the steel stamping, to improve the quality of the steel strip surface and adhesion of a protective cover.
4 ex, 1 tbl
FIELD: steel making.
SUBSTANCE: invention relates to such type of steel that is employed in welded structures such as gas conduits, petroleum pipelines, as well as in high-pressure vessels. Steel according to invention contains, wt %: C 0.02-0.10, Si up to 0.6, Mn 1.5-2.5, P up to 0.015, S up to 0.003, Ni 0.01-2.0, Mo 0.2-0.6, Nb below 0.010, Ti up to 0.030, Al up to 0.070, N up to 0.0060, Fe and unavoidable impurities - the rest, provided that parameter P = 2.7C+0.4Si+Mn+0.8Cr+0.45(Ni+Cu)+2V+Mo-0.5 is within a range of 1.9 to 3.5. Microstructure of steel is mainly composed of martensite and bainite. Steel sheet is manufactured by heating casting to at least Ac3, subjecting it to hot rolling, and cooling sheet at a rate 1°C/sec to temperature not exceeding 550°C. Sheet is further used to manufacture a tube. When laying multilayer welding joint, energy absorbed in the Charpy impact test at -40°C is at least 200 J.
EFFECT: achieved elongation strength at least 800 MPa.
21 cl, 1 dwg, 9 tbl, 5 ex
FIELD: metallurgy; production of low-alloyed cold-resistant steel for underwater sea gas lines at working pressure up to 19 Mpa working at low temperatures.
SUBSTANCE: proposed method includes production of steel blank, heating it to temperature above As3, deformation in controllable mode at specific reduction processes and at total reduction of 50-60% followed by controllable cooling; proposed steel has the following composition, mass-%: carbon, 0.05-0.9; manganese, 1.25-1.6; silicon, 0.15-0.30; chromium, 0.01-0.1; nickel, 0.3-0.6; molybdenum, 0.10-0.25; vanadium, 0.03-0.10; aluminum, 0.02-0.05; niobium, 0.01-0.06; copper, 0.2-0.4; calcium, 0.001-0.005; sulfur, 0.0005-0.005; phosphorus, 0.005-0.015; the remainder being iron; preliminary deformation of blanks is performed at temperature of 950-850°C at total reduction of 50-60%; then, blank is cooled down to temperature of 820-760°C at rate of cooling of 15°C/s on controllable cooling unit and final deformation is performed additionally at temperature of 770-740°C to required thickness of skelp at total reduction of 60-76%; further cooling is performed at higher rate of 35-55°C/s to temperature of 530-350°C, after which skelp is cooled in jacket to temperature of 150±20°C and then in the air. New stage of the proposed method makes it possible to manufacture tubes of 1067-1420 mm in diameter at thickness of walls of 24-40 mm which are used for sea gas pipe lines working at pressure of up to 19 Mpa.
EFFECT: enhanced strength, ductility and cold resistance; enhanced operational reliability; increased service life.
2 tbl, 1 ex
FIELD: metallurgy, namely cold resistant steels.
SUBSTANCE: cold resistant steel for machines and apparatuses, namely in gas- and oil production industry operating in condition of cold climate. Such steel contains, mass %: carbon, 0.15 - 0.22; manganese, 0.3 - 0.6; silicon, 0.15 - 0.40; vanadium, 0.08 -0.12; titanium, 0.001 - 0.040; niobium, 0.001 - 0.040; aluminum, 0.03 - 0.06; sulfur, 0.010 - 0.020; phosphorus, 0.010 - 0.020; cerium, 0.005 - 0.05; calcium, 0.001 - 0.01; barium, 0.001 - 0.01; iron, the balance.
EFFECT: improved strength and cold resistance of steel.