RU2758602C1 - COLUMN I-BEAM WITH A SHELF THICKNESS OF UP TO 40 mm - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention relates to the field of metallurgy, namely to manufacture of hot-rolled stock in the form of column I-beams with a shelf thickness of up to 40 mm, made of low-alloy steel and used for manufacture of welded metal structures suitable for operation in conditions of low temperatures. The column I-beam is made of steel containing components in the following ratio, wt.%: carbon 0.09 to 0.12, manganese 1.55 to 1.70, silicon 0.17 to 0.27, aluminium 0.02 to 0.06, phosphorus ≤ 0.015, sulphur ≤ 0.010, copper ≤ 0.020, nitrogen ≤ 0.008, chromium 0.10 to 0.20, nickel 0.25 to 0.30, vanadium 0.06 to 0.08, molybdenum 0.02 to 0.05, iron the rest. The carbon equivalent value С_eq is no greater than 0.46%.

EFFECT: manufactured I-beam exhibits the required mechanical properties and does not require additional heat treatment of the welded seam after welding.

1 cl, 6 tbl

Description

The invention relates to the field of metallurgy, in particular to the production of rolled products from low-alloy steel of increased strength with a guarantee of weldability without additional heat treatment, used for the manufacture of welded metal structures suitable for operation at low temperatures.

Known column I-beam, traditionally made from low-alloy steel 09G2S according to [1] GOST 19281-2014, containing components in the following ratio, wt.%: Carbon ≤ 0.12; manganese 1.30-1.70; silicon 0.50-0.80; phosphorus ≤ 0.030; sulfur ≤ 0.035; chromium ≤ 0.30; nickel ≤ 0.30; copper ≤ 0.30; iron is the rest.

The disadvantage of the known solution is that rolled products made from steel of the specified composition have a guarantee of weldability, Ceq is not more than 0.46%, but cannot provide mechanical properties for the strength class C390 according to [2] GOST 27772-2015 and the strength class C390B according to [ 3] GOST R 57837-2017.

The closest analogue (prototype) to the claimed invention is an I-beam made of steel 12G2FD according to [4] GOST 19281-2014, which contains carbon, manganese, silicon, aluminum, phosphorus, sulfur, copper, vanadium in the following ratio, wt%: carbon 0 09-0.15; manganese 1.30-1.70; silicon 0.17-0.37; phosphorus ≤ 0.017; sulfur ≤ 0.030; copper 0.15-0.30; chromium ≤ 0.30; nickel ≤ 0.30; vanadium 0.02-0.10; nitrogen ≤ 0.008, iron rest.

The disadvantage of the known solution is that rolled products made from steel of the specified composition, while providing mechanical properties for the strength class C390 according to GOST 27772-2015 and strength class C390B according to GOST R 57837-2017, does not have a guarantee of weldability, Seq more than 0.46 %. Welding of this steel is possible with additional heat treatment of rolled stock before welding, which leads to a complication of manufacturing and an increase in the cost of manufacturing welded structures from such steel.

The listed analogs contain a mandatory list of elements, but do not indicate specific limits for their content and additional alloying elements to obtain the required mechanical properties and special requirements of consumers for weldability.

The technical result, the achievement of which the claimed solution is aimed at, is to increase the mechanical properties (yield stress, tensile strength, relative elongation, impact strength KCV at a temperature of minus 40 ° C) of a column I-beam with a shelf thickness of up to 40 mm, while obtaining a carbon equivalent of no more than 0 , 46%, which contributes to an increase in the consumer properties of rolled products and an improvement in weldability, in view of the absence of additional heat treatment of the weld.

The specified technical result is achieved by the fact that column I-beam with a shelf thickness of up to 40 mm is made of steel containing components in the following ratio, wt%: carbon 0.09-0.12; manganese 1.55-1.70; silicon 0.17-0.27; aluminum 0.02-0.06; phosphorus ≤ 0.015; sulfur ≤ 0.010; copper ≤ 0.020; nitrogen ≤ 0.008; chromium 0.10-0.20; nickel 0.25-0.30; vanadium 0.06-0.08; molybdenum 0.02-0.05; iron is the rest.

The limits of the content of the components in the claimed invention have been obtained empirically.

The applicant has developed a columnar I-beam with a shelf thickness of up to 40 mm made of steel containing components in the following ratio, wt%: carbon 0.09-0.12; manganese 1.55-1.70; silicon 0.17-0.27; aluminum 0.02-0.06; phosphorus ≤ 0.015; sulfur ≤ 0.010; copper ≤ 0.020; nitrogen ≤ 0.008; chromium 0.10-0.20; nickel 0.25-0.30; vanadium 0.06-0.08; molybdenum 0.02-0.05; iron - the rest, providing a carbon equivalent Ceq of not more than 0.46% and at the same time providing an increased value of strength, which guarantees weldability of rolled products without additional heat treatment.

The carbon equivalent is calculated using the formula:

The mechanical properties of the claimed columnar I-beam with a shelf thickness of up to 40 mm correspond to class C390 in accordance with GOST 27772-2015:

- with a shelf thickness of up to 10 mm inclusive

yield point (σ _T ) - not less than 390 N / mm ² ;

temporary resistance (σ _in ) - not less than 520 N / mm ² ;

relative elongation (δ _s ) - not less than 20%;

impact toughness KCV at a temperature of minus 40 ° C - more than 34 J / cm ² .

- with a shelf thickness over 10 to 20 mm inclusive

yield point (σ _T ) - not less than 380 N / mm ² ;

temporary resistance (σ _in ) - not less than 520 N / mm ² ;

relative elongation (δ _s ) - not less than 20%;

impact strength KCV at a temperature of minus 40 ° С - more than 34 J / cm ²

- with a shelf thickness over 20 to 40 mm inclusive

yield point (σ _T ) - not less than 370 N / mm ² ;

temporary resistance (σ _in ) - not less than 490 N / mm ² ;

relative elongation (δ _s ) - not less than 20%;

impact strength KCV at a temperature of minus 40 ° С - more than 34 J / cm ²

The developed columnar I-beam with a shelf thickness of up to 40 mm is made of steel having the following quantitative composition (wt%) and qualitative composition:

• carbon content in the range from 0.09 to 0.12%, with the declared ratio of other components of low-alloy steel determines its strength. A decrease in the carbon content of less than 0.09% leads to a failure to achieve the required strength characteristics. An increase in carbon content in excess of 0.12% reduces ductility, deteriorates toughness and reduces weldability.

• manganese content in the range from 1.55 to 1.70%, with the declared ratio of other components of low-alloy steel, is introduced to increase the strength of steel, as well as reduce the negative effect of sulfur (red brittleness). When the manganese content is less than 1.55%, the required strength characteristics are unattainable. Increasing the manganese content above 1.70% reduces ductility and toughness.

• silicon content in the range from 0.17 to 0.27%, with the declared ratio of other components of low-alloy steel, is necessary for deoxidation of steel and to increase strength. When the silicon content is less than 0.17%, the required deoxidation of the steel does not occur, the steel becomes semi-calm. An increase in silicon content over 0.27% leads to a decrease in toughness and weldability.

• aluminum content in the range from 0.02 to 0.06%, with the declared ratio of other components of low-alloy steel, is a technological additive for steel deoxidation. When the aluminum content is less than 0.02%, the required steel deoxidation does not occur. An increase in the aluminum content of more than 0.06% leads to a complication of casting and an increase in the cost of steel.

• phosphorus content less than or equal to 0.015% (≤ 0.015%), with the declared ratio of other components of low-alloy steel, is a harmful impurity in steel, in an amount of more than 0.015% sharply worsens the ductility, toughness, weldability of steel.

• sulfur content less than or equal to 0.010% (≤ 0.010), with the claimed ratio of other components of low-alloy steel, is a harmful impurity in steel, in an amount of more than 0.010% sharply worsens the strength properties and weldability of steel.

• copper content less than or equal to 0.020% (≤ 0.020), with the declared ratio of other components of low-alloy steel, is an accompanying element, with its amount above 0.020% it does not have a positive effect on steel, but increases its carbon equivalent by its mass fraction.

• nitrogen content less than or equal to 0.008% (≤ 0.008), with the claimed ratio of other components of low-alloy steel, is a carbonitride-forming element that strengthens steel. However, an increase in nitrogen concentration in excess of 0.008% leads to a decrease in toughness and weldability.

• chromium content in the range from 0.10 to 0.20%, nickel in the range from 0.25 to 0.30%, vanadium in the range from 0.06 to 0.08% and molybdenum in the range from 0.02 to 0 , 05% with the claimed ratio of other components of low-alloy steel, are alloying elements that increase the strength characteristics. In the present invention, the best ratio of their mass fractions is selected to maximize strength without loss of weldability.

When the chromium content is below 0.10%, the strength decreases. If its limit of 0.20% is exceeded, the weldability of steel decreases, an unacceptable increase in the carbon equivalent Ceq occurs above 0.46%.

• Nickel content in the range from 0.25 to 0.30% contributes to an increase in toughness, however, with a content less than 0.25%, its effect is insignificant, and exceeding the limit of 0.30% leads to an unacceptable increase in the carbon equivalent Ceq above 0, 46%.

• vanadium content in the range from 0.06 to 0.08% increases the strength characteristics of steel, promotes grain refinement. At a content below 0.06%, the required increase in strength does not occur, at a content above 0.08%, an increase in the carbon equivalent Ceq above 0.46% occurs.

• molybdenum content in the range from 0.02 to 0.05% is necessary to increase strength and improve weldability. Its content below 0.02% does not give the required positive effect, and exceeding 0.05% leads to an unacceptable increase in the carbon equivalent Ceq above 0.46%.

The claimed technical result is achieved using the quantitative and qualitative composition of the components, and does not depend on the sequence (order) of their addition to the melt, as well as on whether they are added in pure or in the form of a ligature.

The technology for the production of rolled products includes: steel smelting by the oxygen-converter method, out-of-furnace treatment, continuous casting, cooling, heating to a temperature of 1250 ° C and subsequent rolling on a universal beam mill with a rolling end temperature in the range of 800-1050 ° C.

This technology for the production of the inventive column I-beam, made of steel, with a chemical composition that provides the specified optimal ratio between the elements and obtaining a carbon equivalent Ceq of not more than 0.46%, allows you to obtain increased strength characteristics of rolled products while ensuring weldability without additional heat treatment of the weld from the consumer.

Table 1 shows the composition of the steel from which the proposed columnar I-beam is made and the composition of steel grades according to GOST 19281-2014.

The results of mechanical tests of a column I-beam with a flange thickness of 35.5 mm, made of steel containing components in the proposed ratio, are shown in Table 2 and Table 3.

The actual mechanical properties of rolled products are in accordance with the requirements of standards for rolled products.

Tables 4, 5, 6 show the test results of welded joints from 40K5 I-beam samples made of steel with strength class C390.

Welding of samples was carried out in a mechanized way in an environment of protective gases, with three grades of wire (Sv-08G2S, Sv-08GSMT, Sv-08GSNT).

All monitored parameters met the requirements of standards for metal structures.

From tables 2, 3, 4, 5, 6 it can be seen that the declared columnar I-beam is characterized by high strength characteristics, while ensuring the guarantee of weldability at the consumer.

Thus, the essence of the claimed technical solution lies in the fact that a column I-beam with a shelf thickness of up to 40 mm, made of steel with a chemical composition, in which the known components are selected in an optimal ratio, provides consumers' requirements for a combination of the required technical characteristics of rolled products and good weldability without additional heat treatment of the weld, which corresponds to the criterion of "novelty".

Analysis of patents and scientific and technical information revealed the absence of features similar to those inherent in the proposed technical solution, which allows us to conclude that it meets the criterion of "inventive step".

The use of the declared columnar I-beam for the manufacture of metal structures at the consumer allows to provide:

1) increasing the strength characteristics of structures;

2) weldability, without additional heat treatment of the weld.

This leads to an expansion of the range of products manufactured and an increase in sales of I-beams.

Experimental study and use of the proposed technical solution at EVRAZ Nizhny Tagil Metallurgical Plant JSC confirms compliance with the criterion of industrial applicability of the invention.

Sources of information

[1] GOST 19281-2014

[2] GOST 27772-2015

[3] GOST R 57837-2017

[4] GOST 19281-2014

Table 1

Components steel Content of steel components, wt% The claimed invention Steel grade 09G2S in accordance with GOST 19281-2014 Steel grade 12G2FD GOST 19281-2014 Examples of 1 2 3 4 5 carbon 0.097 0.114 0.12 ≤ 0.12 0.09-0.15 manganese 1.58 1.68 1.59 1.30-1.70 1.30-1.70 silicon 0.22 0.23 0.23 0.50-0.80 0.17-0.37 aluminum 0.038 0.041 0.034 0.02-0.06 - phosphorus 0.0089 0.0096 0.0100 ≤ 0.030 ≤ 0.030 sulfur 0.0031 0.0027 0.0029 ≤ 0.035 ≤ 0.035 copper 0.010 0.010 0.009 ≤ 0.30 0.15-0.30 nitrogen 0.0049 0.0065 0.0049 ≤ 0.010 ≤ 0.010 chromium 0.119 0.13 0.126 ≤ 0.30 ≤ 0.30 nickel 0.29 0.29 0.29 ≤ 0.30 ≤ 0.30 vanadium 0.064 0.07 0.0069 ≤ 0.12 0.02-0.10 molybdenum 0.041 0.044 0.044 - - iron rest rest rest rest rest

table 2

Steel properties Steel properties by examples (tensile) Rolled steel from the declared steel Requirements according to GOST 27772-2015 Requirements in accordance with GOST R 57837-2017 Examples of 1 2 3 4 5 Limit
fluidity,
N / mm ² 393-392 396-392 423-419 ≤370 ≤375 Temporary
resistance,
N / mm ² 539-534 544-535 573-572 ≤490 ≤520 Relative extension, % 32-30 32-31 28-27 ≤20 ≤20

Table 3

Steel properties Steel properties by examples (impact bending)
Impact strength, J / cm ² , at temperature, ° С Rolled steel from the declared steel Requirements according to GOST 27772-2015 Requirements in accordance with GOST R 57837-2017 Examples of 1 2 3 4 5 KCU
minus 40 371, 362
356, 350 267, 255
243, 241 356, 350
345, 330 ≤34 - KCV
minus 40 247, 220
200, 185 152, 149
144, 138 220, 205
201, 197 ≤34 ≤34

Table 5

Brand
welding wire Sampling location Impact strength KCV, J / cm ² , at a temperature of minus 40 ° С SP 53-101-98, SP 70.13330.2012 not less than 34 seam axis fusion line Sv-08G2S Wall 52, 69, 80, 85, 96, 100 96, 168, 188, 216, 315, 340 71, 102, 106, 110, 120, 130 55, 205, 210, 230, 277, 368 35, 102, 126, 130, 158, 193 246, 258, 261, 290, 302, 342 Shelf 38, 45, 52, 97, 120, 143 220, 241, 242, 243, 256, 280 62, 71, 73, 82, 85, 93 221, 238, 257, 267, 280, 281 55, 57, 78, 83, 87, 102 170, 247, 255, 270, 291, 300 Sv-08GSMT Wall 85, 124, 140, 146, 170, 206 193, 284, 285, 328, 353, 368 83, 94, 115, 123, 150, 204 252, 284, 291, 317, 360, 373 72, 121, 131, 141, 152, 177 260, 334, 341, 357,369, 370 Shelf 93, 177, 172, 180, 216, 218 197, 227, 240, 243, 250, 360 70, 72, 75, 80, 96, 133 258, 272, 320, 331, 322, 333 57, 75, 77, 108, 110, 137 178, 227, 235, 262, 278, 343 Sv-08GSNT Wall 76, 82, 90, 122, 133, 137 224, 230, 231, 233, 243, 247 63, 68, 78, 80, 82, 102 220, 253, 255, 261, 264, 281 57, 63, 83, 96, 100, 113 206, 243, 253, 355, 344, 323 Shelf 55, 76, 81, 87, 91, 97 171, 205, 208, 212, 246, 295 72, 73, 85, 86, 90, 92 175, 191, 202, 206, 200, 222 77, 81, 83, 85, 87, 93 178, 190, 197, 206, 233, 247

Table 6

Brand
welding
wire A place
selection
sample Hardness, HV SP 53-101-98, SP 70.13330.2012 no more than 320 Actual values base metal heat affected zone the seam Sv-08G2S Wall 137, 139, 141,
141, 141 152, 156, 160, 160,
164, 164.168 144, 148, 152, 152, 156, 156, 160, 164 141, 141, 141,
144, 148 141, 144, 148, 152,
156, 160, 164 132, 135, 137, 139, 144, 148, 152, 156 141, 141, 141,
144, 148 152, 156, 160, 160,
164, 164.168 137, 139, 141, 144, 148, 160, 164 Shelf 137, 137, 137,
139, 139, 139, 141 137, 139, 141, 144,
148, 152, 156 137, 139, 141, 144, 144, 148, 148 137, 139, 141,
141, 144, 148 144, 148, 152, 152, 152,156, 156, 156 141, 144, 148, 152, 152, 156, 156 141, 141, 141,
144, 148 152, 152, 152,156, 156, 156, 160, 164 141, 144, 148, 152, 156, 160, 164 Sv-08GSMT Wall 141, 141, 144,
144,148,148 144, 148, 152, 156, 160, 164, 168 144, 148, 160, 160, 164, 164, 168 141, 141, 144,
144, 148, 148 144, 148, 152, 156, 160, 164, 168 168, 168, 168,
180, 184

Continuation of table 6

Brand
welding
wire A place
selection
sample Hardness, HV SP 53-101-98, SP 70.13330.2012 no more than 320 Actual values base metal heat affected zone the seam 137, 137, 139, 139,
141, 144, 148 144, 144, 148, 148,
152, 156, 160, 164 127, 130, 135,
141, 172, 17 Shelf 137, 139, 137,
139, 141, 141 144, 148, 152, 152,
156, 156, 160 137, 139, 144, 144, 148, 148, 152, 156 141, 141, 141,
144, 148, 141, 144, 144, 144,
148, 148, 148 141, 141, 144,
152, 156, 148 141, 141, 144,
144, 148, 148 144, 148, 152, 156,
160, 164, 168 168, 168, 168,
180, 184 Sv-08GSNT Wall 141, 141, 141,
144, 148 152, 152, 156, 156,
160, 160, 164, 164 172, 176, 180,
184, 188, 188 137, 139, 141, 144,
144, 148, 148 152, 156, 160, 160,
164, 164, 168 168, 172, 172, 176, 176, 180, 184 137, 139, 141, 141,
144, 148 152, 156, 160, 164,
168, 172, 176 160, 164, 172, 176, 180, 184, 188 Shelf 132, 135, 137, 137,
139, 139, 141 152, 156, 168,
168, 172, 176 127, 130, 141, 144, 148, 160, 164 141, 141, 141,
144, 148 160, 164, 172, 172,
176, 176, 180, 184 172, 176, 180, 184, 188, 196, 200 137, 137, 137, 139, 139, 139, 141 152, 152, 156, 156, 160, 164, 172, 176 132, 135, 144, 148, 180, 184, 196, 200

Claims (3)

Column I-beam with a shelf thickness of up to 40 mm, made of low-alloy steel, characterized in that it is made of steel containing components in the following ratio, wt%: Carbon 0.09 - 0.12 Manganese 1.55 - 1.70 Silicon 0.17 - 0.27 Aluminum 0.02 - 0.06 Phosphorus ≤ 0.015 Sulfur ≤ 0.010 Copper ≤ 0.020 Nitrogen ≤ 0.008 Chromium 0.10 - 0.20 Nickel 0.25 - 0.30 Vanadium 0.06 - 0.08 Molybdenum 0.02 - 0.05 Iron rest and having a carbon equivalent C _eq , which is not more than 0.46%, while for a shelf thickness of up to 10 mm it has a yield strength (σ _T ) of at least 390 N / mm ² and a _{ultimate strength (σ in} ) of at least 520 N / mm ² , for a shelf thickness of over 10 mm to 20 mm inclusive, it has a yield point (σ _T ) of at least 380 N / mm ² and a _{ultimate strength (σ in} ) of at least 520 N / mm ² , and for a shelf thickness of over 20 up to 40 mm inclusive, it has a yield point (σ _T ) of at least 370 N / mm ² and a _{ultimate tensile strength (σ c} ) of at least 490 N / mm ² .