CN107779759A - Boron-containing bainite steel rail with excellent delayed fracture resistance and production method thereof - Google Patents
Boron-containing bainite steel rail with excellent delayed fracture resistance and production method thereof Download PDFInfo
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- CN107779759A CN107779759A CN201610737596.2A CN201610737596A CN107779759A CN 107779759 A CN107779759 A CN 107779759A CN 201610737596 A CN201610737596 A CN 201610737596A CN 107779759 A CN107779759 A CN 107779759A
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- bainite
- delayed fracture
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- 229910001563 bainite Inorganic materials 0.000 title claims abstract description 45
- 230000003111 delayed effect Effects 0.000 title claims abstract description 17
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 14
- 229910000831 Steel Inorganic materials 0.000 title abstract description 69
- 239000010959 steel Substances 0.000 title abstract description 69
- 229910052796 boron Inorganic materials 0.000 title abstract description 15
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 title abstract description 14
- 238000001816 cooling Methods 0.000 claims abstract description 24
- 238000010438 heat treatment Methods 0.000 claims abstract description 11
- 238000005098 hot rolling Methods 0.000 claims abstract description 10
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 8
- 239000012535 impurity Substances 0.000 claims abstract description 4
- 229910052742 iron Inorganic materials 0.000 claims abstract description 4
- 239000000203 mixture Substances 0.000 claims description 19
- 238000000034 method Methods 0.000 abstract description 2
- 238000003723 Smelting Methods 0.000 abstract 1
- 238000005266 casting Methods 0.000 abstract 1
- 238000009749 continuous casting Methods 0.000 abstract 1
- 230000009466 transformation Effects 0.000 description 13
- 239000000126 substance Substances 0.000 description 12
- 239000010936 titanium Substances 0.000 description 11
- 239000000047 product Substances 0.000 description 9
- 239000011651 chromium Substances 0.000 description 8
- 229910052799 carbon Inorganic materials 0.000 description 7
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 6
- 229910001566 austenite Inorganic materials 0.000 description 6
- 230000000694 effects Effects 0.000 description 6
- 238000005204 segregation Methods 0.000 description 6
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 5
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 5
- 238000007792 addition Methods 0.000 description 5
- 229910045601 alloy Inorganic materials 0.000 description 5
- 239000000956 alloy Substances 0.000 description 5
- 238000005275 alloying Methods 0.000 description 5
- 229910001567 cementite Inorganic materials 0.000 description 5
- 238000005516 engineering process Methods 0.000 description 5
- 229910052739 hydrogen Inorganic materials 0.000 description 5
- 239000001257 hydrogen Substances 0.000 description 5
- KSOKAHYVTMZFBJ-UHFFFAOYSA-N iron;methane Chemical compound C.[Fe].[Fe].[Fe] KSOKAHYVTMZFBJ-UHFFFAOYSA-N 0.000 description 5
- 229910000859 α-Fe Inorganic materials 0.000 description 5
- 229910000734 martensite Inorganic materials 0.000 description 4
- 229910052757 nitrogen Inorganic materials 0.000 description 4
- 229910052710 silicon Inorganic materials 0.000 description 4
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 3
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 3
- 230000008859 change Effects 0.000 description 3
- 230000007812 deficiency Effects 0.000 description 3
- 238000013461 design Methods 0.000 description 3
- 239000011572 manganese Substances 0.000 description 3
- 238000005457 optimization Methods 0.000 description 3
- 238000012545 processing Methods 0.000 description 3
- 239000010703 silicon Substances 0.000 description 3
- 229910052719 titanium Inorganic materials 0.000 description 3
- 230000005641 tunneling Effects 0.000 description 3
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 2
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 2
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 2
- 230000006378 damage Effects 0.000 description 2
- 239000010955 niobium Substances 0.000 description 2
- 229910001562 pearlite Inorganic materials 0.000 description 2
- 229920001296 polysiloxane Polymers 0.000 description 2
- 238000001556 precipitation Methods 0.000 description 2
- 238000003908 quality control method Methods 0.000 description 2
- 238000010791 quenching Methods 0.000 description 2
- 230000000171 quenching effect Effects 0.000 description 2
- 238000011160 research Methods 0.000 description 2
- 238000003466 welding Methods 0.000 description 2
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 1
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 1
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 1
- 230000001133 acceleration Effects 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- 239000011575 calcium Substances 0.000 description 1
- 229910052804 chromium Inorganic materials 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000000280 densification Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 230000036541 health Effects 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 239000004615 ingredient Substances 0.000 description 1
- 229910052749 magnesium Inorganic materials 0.000 description 1
- 239000011777 magnesium Substances 0.000 description 1
- 229910052748 manganese Inorganic materials 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000010310 metallurgical process Methods 0.000 description 1
- 229910052750 molybdenum Inorganic materials 0.000 description 1
- 239000011733 molybdenum Substances 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 229910052758 niobium Inorganic materials 0.000 description 1
- GUCVJGMIXFAOAE-UHFFFAOYSA-N niobium atom Chemical compound [Nb] GUCVJGMIXFAOAE-UHFFFAOYSA-N 0.000 description 1
- 150000004767 nitrides Chemical class 0.000 description 1
- 238000009377 nuclear transmutation Methods 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 238000005096 rolling process Methods 0.000 description 1
- 235000015170 shellfish Nutrition 0.000 description 1
- 239000006104 solid solution Substances 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 230000006641 stabilisation Effects 0.000 description 1
- 238000011105 stabilization Methods 0.000 description 1
- 238000005728 strengthening Methods 0.000 description 1
- 230000001629 suppression Effects 0.000 description 1
- 238000005496 tempering Methods 0.000 description 1
- 238000000844 transformation Methods 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
- 229910052720 vanadium Inorganic materials 0.000 description 1
- LEONUFNNVUYDNQ-UHFFFAOYSA-N vanadium atom Chemical compound [V] LEONUFNNVUYDNQ-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/005—Modifying the physical properties by deformation combined with, or followed by, heat treatment of ferrous alloys
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/04—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for rails
- C21D9/06—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for rails with diminished tendency to become wavy
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/14—Ferrous alloys, e.g. steel alloys containing titanium or zirconium
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/32—Ferrous alloys, e.g. steel alloys containing chromium with boron
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/002—Bainite
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Heat Treatment Of Articles (AREA)
- Heat Treatment Of Steel (AREA)
Abstract
The invention provides a boron-containing bainite steel rail with excellent delayed fracture resistance and a production method thereof, wherein the steel rail comprises the following components in percentage by weight: c ]: 0.18% -0.26%; [ Si ]: 1.30% -1.70%; [ Mn ]: 1.75% -2.15%; [ Cr ]: 0.30% -0.70%; [ Mo ]: 0.15% -0.40%, [ P ] is less than or equal to 0.020%, [ S ] is less than or equal to 0.010%, and [ B ]: 0.0006% -0.0015%, [ Ti ]: 0.01% -0.03%, [ H ]: 0.00017% or less, and the balance of iron and inevitable impurity elements; the production method comprises the steps of smelting, continuous casting, casting blank heating, hot rolling and heat treatment, wherein the heat treatment is that the steel rail is cooled to 700 +/-60 ℃ or 600 +/-60 ℃ in air after hot rolling, then cooled to 300 +/-40 ℃ at the cooling speed of 0.5 ℃/s-4 ℃/s, and then cooled to room temperature in air. The bainite steel rail produced by the method can be applied to railways through on-line heat treatment, and the delayed fracture resistance of the steel is improved.
Description
Technical field
The invention belongs to metal processing sectors, more particularly to a kind of boracic bainite with excellent resistance for delayed fracture
Rail.
Background technology
From the seventies in last century so far, the exploitation of bainite rail has had the history of nearly 50 years.Bainite rail due to
Its excellent application performance and be described as the rail of 21st century.So far, the application of bainite rail is still very limited
, cost performance that this is largely determined by bainite rail is relatively low, production technology can not also meet large-scale industrial production will
Ask.
Presently disclosed bainite rail chemical composition ranges are wide, and difficulty is brought to rail control of product quality.Experiment
Research shows:After rail hot rolling under conditions of continuous air cooling, bainite structure is typically by the high, medium and low temperature transformation production of austenite
Thing is formed, and when the chemical composition ranges of steel are excessively wide in range, above-mentioned high, medium and low temperature organizational composition ratio and yardstick will occur more
Big change, therefore can cause properties of product that larger fluctuation occurs, it is unfavorable for the stabilization of product quality, is less useful for welding quality
Control.
Bainite rail intensity has reached high-strength (1200MPa) or strong (1400MPa) grade of steel of superelevation is other, to high-strength steel
Speech, delayed fracture resistance ability declines with the raising of intensity, therefore the generally resistance to delay of high strength bainite steel rail
Fracture property is less than pearlite steel rail, is embodied in elongation percentage is relatively low, fatigue crack growth rate is higher etc..Therefore shellfish is improved
The delayed fracture resistance ability of family name's body rail, steel is improved to the Technological adaptability of existing metallurgical process controlled level, is successfully to produce
Bainite rail has to solve the problems, such as.Delayed fracture is usually as caused by the residual hydrogen in steel is higher, therefore, improves steel
Resistance for delayed fracture mainly by controlling residual hydrogen amount to realize, but by residual hydrogen amount control below 0.0001% to steel
Metallurgical production brings larger pressure.
Invention《Bainitic steel rail with high resistance to surface fatigue damage and high-wearing feature》(application number:
99800029.9) the bainite rail chemical composition disclosed is " carbon 0.15%-0.45%, silicon 0.1%-2.00%, manganese
0.20%-3.00%, chromium 0.20%-3.00%, the element selected along with one or more from following elements group:Molybdenum
0.01%-1.00%, copper 0.05%-0.50%, nickel 0.05%-4.00%, titanium 0.01%-0.05%, vanadium 0.01%-
0.30%, niobium 0.005%-0.05%, boron 0.0001%-0.0050%, magnesium 0.0010%-0.0100%, calcium 0.0010%-
0.015%.Although " boracic, chemical composition ranges are very wide in range, and difficulty is brought to rail control of product quality.The invention limits
Determined carbide in steel tissue signature " a kind of bainitic steel rail steel with good resistance to surface fatigue damage and wearability, extremely
Small part contains bainite structure, it is characterised in that the carbide that its major axis is between 100nm~1000nm is in the bayesian
Body tissue one is given between the gross area shared on section is the section 10%~50%.”
Invention《Improved non-carbide bainitic steel and its production method》(application number:96192013.0) disclosed in bayesian
The chemical composition of body steel includes C0.05-0.50%, Si and/or Al 1.00-3.00%, Mn0.50-2.50%, Cr0.25-
2.50%, Ni0-3.00%, S0-0.025%, W0-1.00%, Mo0-1.00%, Cu0-3%, Ti0-0.10%, V0-
0.50%, and B0-0.005%, Fe be remaining and adjoint impurity.Although boracic, chemical composition ranges are very wide in range, give rail product
Quality control brings difficulty.The invention does not propose specific technological parameter yet, is only proposed for production technology " from its rolling temperature
The continuous natural cooling rail is to room temperature in atmosphere, or accelerates to cool down the rail to room temperature ".
Invention《The tough weldable air-cooled great health bainitic steel of the special superelevation of railroad frog》(application number:98124899.3) open
Bainitic steel chemical composition " (Wt%) C0.10-0.6, Si≤2.65, Mn0.50-3.20, Cr0.20-2.80, Ni≤3.50,
Mo≤2.00, remainder are Fe, and the following elements (Wt%) of one or two or more kinds are added on its basic ingredient:Nb≤
0.20th, V≤0.20, Ti≤0.20, Re≤0.10, B≤0.008." production technology is empty after 850 DEG C~1000 DEG C austenitizings
Cold ,≤650 tempering are become a useful person.Temper, complex manufacturing are needed after the invention hot rolling and air cooling, it is difficult to ensure that rail quality is stable
Property.
The content chemical composition ranges that above three invention is opened are wide in range, and bainite rail chemical composition ranges are wide, to steel
Rail control of product quality brings very big difficulty.After rail hot rolling under conditions of continuous air cooling, bainite structure is typically by Ovshinsky
The high, medium and low temperature transmutation product of body is formed, when the chemical composition ranges of steel are excessively wide in range, above-mentioned high, medium and low temperature organizational composition
Larger change will occur for ratio and yardstick, therefore can cause properties of product that larger fluctuation occurs, and be unfavorable for the steady of product quality
It is fixed, it is less useful for the control of welding quality.
The content of the invention
There is provided a kind of with excellent resistance for delayed fracture it is an object of the invention to overcome above mentioned problem and deficiency
Boracic bainite rail, bainite rail obdurability after burning optimization on line are superior to hot rolled bainite steel rail, are returned without follow-up
Fire processing, it is possible to applied on railway.
The object of the present invention is achieved like this:
Within the scope of the chemical composition ranges of steel are limited in reasonably;Add alloying element and realize tunneling boring bainite group
The purpose knitted, but alloy total amount is unsuitable too high, it is too high, increase cost and increase the tendency that excessive martensite is separated out in steel
With the tendency of element segregation, steel toughness plasticity deteriorates or performance inconsistency is serious, and alloy total amount is too low, can not obtain tunneling boring and be
The bainite rail of bainite structure;Further boron element is limited in:In the range of 0.0006-0.0015%, boron member is avoided
The adverse effect of plain On Impact Toughness, while the resistance for delayed fracture of steel gets a promotion, the upper limit of the residual hydrogen of steel can improve to
0.00017%.Therefore alloying element scope proposed by the present invention is more accurate.
Design composition within the scope of bainite rail after burning optimization on line obdurability be superior to hot rolled bainite steel rail,
Without follow-up temper, it is possible to applied on railway.
A kind of excellent boracic bainite rail of resistance for delayed fracture and its production method, the composition of the rail is by weight
Percentages are as follows:[C]:0.18%-0.26%;[Si]:1.30%-1.70%;[Mn]:1.75%-2.15%;[Cr]:
0.30%-0.70%;[Mo]:0.15%-0.40%, [P]≤0.020%, [S]≤0.010%, [B]:0.0006%-
0.0015%, [Ti]:0.01%-0.03%, [H]:≤ 0.00017%, remaining is iron and inevitable impurity element.
Present component design reason is as follows:
Carbon is maximally effective intensified element, thus it is acceptable in engineering under the premise of, its content is higher, and cost is lower,
Therefore it should try one's best and improve its content, but no more than 0.26%, martensite proportion is too high in steel if more than 0.26%,
The toughness plasticity of steel can be affected;Its content not preferably less than 0.18% simultaneously, otherwise needs to increase containing for other alloying elements
Measure to strengthen steel matrix, cost of alloy is too high, and steel grade does not have competitiveness, and carbon content within this range, realizes the good of obdurability
Good matching.
Silicon generally as reinforced ferrite element add steel in, in this steel, it primarily serve suppress ε-carbide or
The effect that cementite separates out, the temperature that converted the austenite to due to the segregation of carbon of non-carbide precipitate is less than room temperature, with remnants
The form of austenite remains.Typical bainite was divided into upper bainite and lower bainite in the past, wherein containing in difference
The cementite that position separates out, cementite can cause the toughness plasticity of steel to significantly reduce, therefore low-carbon bainite steel answering in engineering
With seldom, only ULCB is applied.With the addition of element silicon, the cementite in bainitic steel, which separates out, to be pressed down
System, the non-carbide bainitic steel toughness plasticity that continuous coo1ing obtains significantly improve.Silicone content is less than 1.30%, then can not realize suppression
The purpose that cementite processed separates out, silicone content is higher than 1.70%, and remained austenite content increases in steel and carbon content is too low, residual austenite
The stability of body reduces, and the toughness plasticity of steel equally reduces.
Manganese element is than more typical cheap, displaced type solution strengthening element, and in this steel, it is strong to have primarily served phase transformation
The effect of change, therefore in order to reduce the cost of alloy of steel, addition is bigger.Addition is less than 1.75%, then needs to increase it
The content of his expensive alloying elements, therefore be both economical higher than 1.75%, but addition should not also be higher than 2.15%, add
The trend for entering the too high then element segregation of amount increases, and obvious reduce will occur for another aspect structure property especially toughness plasticity.
Needed to reduce the trend of segregation by the control of Mn contents below 2.15%, the portion of quenching degree deficiency
Divide and usually made up by adding Cr members.
Cr is the quenching degree element for significantly improving steel, and appropriate Cr is added in steel, can also improve ferrite electrode potential, is promoted
The surface of steel is formed the oxide-film of densification, improve its corrosion resistance.Cr contents are low, hardness deficiency after heat treatment, Cr too high levels,
Increase cost of alloy, therefore, in the range of present invention control Cr contents 0.3%~0.7%.
Molybdenum element is typical postponement perlitic transformation, separates bainite and perlitic transformation C curve, so that steel is easy
It is the alloying element for making rail tunneling boring to obtain bainite structure under the conditions of hot rolling and air cooling in bainite transformation occurs.
0.15% is should be higher than that to reach above-mentioned purpose Mo contents, but it is sufficient that below 0.40%.
Boron:In bainitic steel, because boron can effectively suppress in Grain Boundary Segregation the precipitation of pro-eutectoid ferrite, therefore B
With the compound additions of Mo, it can be individually added into than Mo and more significantly postpone ferrite and pearlite transformation, because boron element adds
Amount is less and ferro-boron is cheap, therefore boron element often turns into the first choice of bainitic steel.Substantial amounts of research shows, because boron is in crystalline substance
Boundary's segregation also easily causes the loss of impact flexibility, therefore is just added without boron element when requiring higher impact flexibility.When
When boron element is more than 0.0015%, the impact flexibility of bainite rail is decreased obviously, and by boron element be limited in 0.0015% with
When lower, impact flexibility remains at higher level, and during B < 0.0006%, the raising to elongation percentage does not act on, therefore, control
[B]:0.0006%-0.0015%.After adding micro boron element, the resistance for delayed fracture of steel (elongation percentage significantly improves)
Get a promotion, the upper limit of the residual hydrogen of bainitic steel rail steel can be improved to 0.00017%.
Ti is strong nitride forming element, after carrying out trace Ti processing in steel, can separate out fine TiN and TiCN grains
Son, hinders Austenite Grain Growth, crystal grain thinning, and another aspect Ti can be combined with N, be reduced BN formation rate, reduce BN
Harm, give full play to solid solution B improve hardenability effect.Ti contents 0.01-0.03%, Ti nitrogen fixation effect are optimal, and titanium contains
Amount is less than 0.01%, does not have an effect of fixed nitrogen, and Ti content is higher than 0.03%, can also be formed while fixed nitrogen thick Ti (N,
C) non-metallic inclusion, purity of steel is reduced.
A kind of production method of the excellent boracic bainite rail of resistance for delayed fracture, including smelting-continuous casting-strand
Heating-hot rolling-heat treatment, the heat treatment are air-cooled to 700 DEG C ± 60 DEG C or 600 DEG C ± 60 DEG C later for rail hot rolling, it
300 DEG C ± 40 DEG C are cooled to 0.5 DEG C/s-4 DEG C/s cooling rate afterwards, is then air-cooled to room temperature.
700 DEG C ± 60 DEG C or 600 DEG C ± 60 DEG C are air-cooled to after rail hot rolling, rail hot rolling and air cooling has been able to suppress first
The precipitation of eutectoid ferrite, as long as therefore start more than transition temperature (Bs) in bainite, according to environment temperature (environment temperature≤
0 DEG C is air-cooled to 600 DEG C ± 60 DEG C, environment temperature>0 DEG C is air-cooled to 700 DEG C ± 60 DEG C) will start fast cooling temperature control compared with
Within the scope of narrow, you can to reach the purpose of limitation cooling velocity fluctuation.
Cooled down with 0.5 DEG C/s-4 DEG C/s cooling velocity, be that cooling rate is excessively slow, structure of steel because when cooling rate is less than 0.5 DEG C/s
In have more medium temperature block type transformation and occur, this structure stability is poor, and cooling rate is higher than 4 DEG C/s, martensite institute accounting in steel
Regular meeting increases sharply, and the fracture mechanical property of steel can be caused to deteriorate, therefore, cooling velocity is preferably controlled between 0.5-4 DEG C/s.
Accelerate cooling final cooling temperature control at 300 DEG C ± 40 DEG C, exactly in order that accelerating cooling to terminate in bainite transformation
In the range of temperature (Bs-Bf), 300 DEG C ± 40 DEG C can further make acceleration cooling termination temperature fall narrow scope it
Interior, not starting to bainite transformation also higher than 340 DEG C, either transformation amount is seldom or medium temperature bainite proportion is higher, unfavorable
In the toughness for improving steel, less than 260 DEG C, bainite cryo tissue, even martensite transfor mation proportion are too high, the disruptive force of steel
Penalty is learned, to terminating to accelerate the temperature range of cooling to be any limitation as, that is, the formation for avoiding high temperature transformation tissue is also reduced
The formation of low-temperature transformation tissue.So accelerate cooling final cooling temperature control at 300 DEG C ± 40 DEG C.
Above-mentioned process technology scheme by technological specification be limited in it is one narrower and rational within the scope of so that starting
Cool down and more they tended to the structural state for terminating cooling consistent, to obtain uniformly tiny bainite structure, guarantee rail quality is steady
It is fixed.The uniformity of tissue morphology is then influenceed beyond the scope.
The beneficial effects of the present invention are the bainite rail within the scope of design composition exists through burning optimization on line can
Applied on railway, and the resistance for delayed fracture of steel gets a promotion.
Embodiment
Below by embodiment, the present invention is further illustrated.
The embodiment of the present invention is according to the component proportion of technical scheme, including at refining-continuous casting-heating strand-hot rolling-heat
Reason, the composition of steel of the embodiment of the present invention are shown in Table 1.The main technologic parameters of steel of the embodiment of the present invention are shown in Table 2.Steel of the embodiment of the present invention
Performance be shown in Table 3.
The composition (wt%) of the steel of the embodiment of the present invention of table 1
The main technologic parameters of the steel of the embodiment of the present invention of table 2
The performance of the steel of the embodiment of the present invention of table 3
Claims (2)
- A kind of 1. excellent boracic bainite rail of resistance for delayed fracture, it is characterised in that the composition of the rail by weight hundred Divide as follows than counting:C]:0.18%-0.26%;[Si]:1.30%-1.70%;[Mn]:1.75%-2.15%;[Cr]: 0.30%-0.70%;[Mo]:0.15%-0.40%, [P]≤0.020%, [S]≤0.010%, [B]:0.0006%- 0.0015%, [Ti]:0.01%-0.03%, [H]:≤ 0.00017%, remaining is iron and inevitable impurity element.
- 2. a kind of production method of the excellent boracic bainite rail of resistance for delayed fracture described in claim 1, including Refining-continuous casting-heating strand-hot rolling-heat treatment, it is characterised in that the heat treatment is air-cooled to 700 later for rail hot rolling DEG C ± 60 DEG C or 600 DEG C ± 60 DEG C, 300 DEG C ± 40 DEG C are cooled to 0.5 DEG C/s-4 DEG C/s cooling rate afterwards, is then air-cooled to room Temperature.
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Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
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CN110607488A (en) * | 2019-09-02 | 2019-12-24 | 鞍钢股份有限公司 | Online heat treatment steel rail for high-speed railway and manufacturing method thereof |
CN112276030A (en) * | 2020-10-13 | 2021-01-29 | 攀钢集团攀枝花钢铁研究院有限公司 | High-strength delayed fracture-resistant hot-rolled steel rail and preparation method thereof |
CN112301200A (en) * | 2020-10-13 | 2021-02-02 | 攀钢集团攀枝花钢铁研究院有限公司 | Steel rail with delayed fracture resistance and preparation method thereof |
CN117327985A (en) * | 2023-10-24 | 2024-01-02 | 包头钢铁(集团)有限责任公司 | B, ti microalloyed hot rolled bainite steel rail and manufacturing method thereof |
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Publication number | Priority date | Publication date | Assignee | Title |
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CN110607488A (en) * | 2019-09-02 | 2019-12-24 | 鞍钢股份有限公司 | Online heat treatment steel rail for high-speed railway and manufacturing method thereof |
CN112276030A (en) * | 2020-10-13 | 2021-01-29 | 攀钢集团攀枝花钢铁研究院有限公司 | High-strength delayed fracture-resistant hot-rolled steel rail and preparation method thereof |
CN112301200A (en) * | 2020-10-13 | 2021-02-02 | 攀钢集团攀枝花钢铁研究院有限公司 | Steel rail with delayed fracture resistance and preparation method thereof |
CN112276030B (en) * | 2020-10-13 | 2021-11-19 | 攀钢集团攀枝花钢铁研究院有限公司 | High-strength delayed fracture-resistant hot-rolled steel rail and preparation method thereof |
CN117327985A (en) * | 2023-10-24 | 2024-01-02 | 包头钢铁(集团)有限责任公司 | B, ti microalloyed hot rolled bainite steel rail and manufacturing method thereof |
CN117327985B (en) * | 2023-10-24 | 2024-10-29 | 包头钢铁(集团)有限责任公司 | B, ti microalloyed hot rolled bainite rail and manufacturing method thereof |
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