CN107699792B - A kind of low temperature resistant micro alloyed steel and production technology - Google Patents
A kind of low temperature resistant micro alloyed steel and production technology Download PDFInfo
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- CN107699792B CN107699792B CN201710915092.XA CN201710915092A CN107699792B CN 107699792 B CN107699792 B CN 107699792B CN 201710915092 A CN201710915092 A CN 201710915092A CN 107699792 B CN107699792 B CN 107699792B
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- 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
- 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
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
- C21D8/0226—Hot rolling
-
- 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
- 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
- C22C38/26—Ferrous alloys, e.g. steel alloys containing chromium with niobium or tantalum
-
- 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
- C22C38/28—Ferrous alloys, e.g. steel alloys containing chromium with titanium or zirconium
-
- 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
- C21D2211/005—Ferrite
-
- 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
- C21D2211/009—Pearlite
Abstract
The present invention relates to a kind of low temperature resistant micro alloyed steel, the chemical composition comprises the following components in percentage by weight of the micro alloyed steel are as follows: C:0.075%~0.1%；Si:0.10%~0.30%；Mn:1.0%~1.40%；Cr:0.25%~0.50%；Nb:0.020%~0.030%；Ti:0.015%~0.025%；Al :≤0.015%；P :≤0.010%；S :≤0.010%；Surplus is Fe and inevitable impurity element；The inevitable impurity element includes gas content and other inevitable impurity elements, the gas content: molten steel [H]≤2.0ppm, slab [H]≤2ppm, [O]≤30ppm, [N]≤50ppm；Other described inevitable impurity element≤1%.Meanwhile the invention further relates to a kind of production technologies of low temperature resistant micro alloyed steel.The present invention effectively controls growing up for austenite grain by the micro-alloying technology of Nb+Ti in steel rolling heating process, final to obtain ferrite-pearlite superfine grained structure, and grain size reaches 10 grades or more, meets the technical requirements of low temperature indices；Yield strength > 355MPa of micro alloyed steel of the present invention；Tensile strength > 550MPa；- 60 DEG C of low-temperature impact Ak > 27J；Elongation after fracture > 22%.
Description
Technical field
The present invention relates to construction(al)steel technical field more particularly to a kind of low temperature resistant micro alloyed steel and production technologies.
Background technique
Due to the fast development of world economy, various countries increasingly increase Demand of Oil & Gas amount, and oil-gas mining is gradually walked from land
To ocean, move towards high and cold from low temperature, this puts forward new requirements to low temperature resistant steel construction steel and H profile steel exploitation.
On variety development, for cryogenic property index request, generally use in the world low carbon manganese steel C (< 0.12%)+(Nb,
V is micro-) alloying process, there is reflection in Russian standard and Europe superscript.The process route of fine grain controlled rolling is used in microstructure,
To guarantee cryogenic property.But Hi-grade steel, low-temperature flexibility height, performance are badly in need of in the low temperature resistant steel construction steel in China and H profile steel production
The kind of stability types.
By taking Russian Yamal engineering, Western Canadian Arctic project as an example.The peninsula Yamal is located at Siberia the north, belongs to the arctic
Subprovince, permafrost haorizon blazon, and the lowest temperature can construct, want to rolling shapes and H profile steel performance at -70 DEG C for annual only 3 months
Ask harsh.Extremely frigid zones oil gas rolling shapes and H profile steel feature: high-intensitive, excellent low-temperature flexibility (- 50 DEG C), it is antifatigue,
Anti- lamellar tearing, good weldability.In production technology using blast-melted-molten iron pre-desulfurization-converter smelting-LF furnace (or
RH furnace) refining-steel plate or casting for shaped blank continuous-structural steel plate and H profile steel factory controlled rolling fine grain production process route it is enterprising
Row.
Low-carbon microalloyed fine grain controlled rolling steel grade, the urgent technical problem faced are how to solve continuous casting billet transverse fissure technology
Problem.
It includes 3 processes that microalloying low-alloy steel slab crackle, which generates: in the forming process of initial solidification shell, along with
The generation of peritectic reaction, initial solidification shell is by the frictional force of crystallizer, Xiang Bianli, thermal stress, ferrostatic pressure etc., due to green shell
The inhomogeneities of growth, when above-mentioned stress is more than the critical intensity of solidification front steel, in green shell weakness (wave when generally oscillation mark
Paddy) microcrack is generated, meanwhile, the sediments such as AlN, Nb (CN), V (CN) are precipitated along austenite grain boundary, lead to the netted iron of crystal boundary
Ferritic generates, and weakens grain-boundary strength, causes intercrystalline fracture, and macro manifestations are the expansion of plasticity low ebb area (brittle zone) temperature range
Greatly；Secondary cooling zone inhomogeneous cooling is even to cause crack propagation at Local cooling intensity is excessive；In aligning area, slab straightening temperature enters crisp
Property section, arc slab inner arc is under pressure by tension, outer arc, concentrates since the notch effect of oscillation mark generates stress, accelerates
The formation and extension of crackle, finally crack in the slab inner arc by tension.
Summary of the invention
In view of above-mentioned analysis, the present invention is intended to provide a kind of low temperature resistant micro alloyed steel and production technology, to solve
The problem of continuous casting billet surface of existing low temperature resistant micro alloyed steel and H profile steel is easy to produce transverse crack.
The metallurgical mechanism to solve the above problems is: 1) carbon content is reduced to the lower limit of peritectic reaction as far as possible in steel, reduces
The negative effect of peritectic reaction；2) it solves after growing up because of the precipitation of austenite grain boundary particle as crystal boundary ferrite net forming core matter
Point, and then control the slab plasticity low ebb warm area occurred and expand problem.Therefore, how to avoid the generation of crystal boundary ferrite net is
Core technology is crucial.The present invention is in view of the above-mentioned problems, addition can be in the microalloying low-alloy steel system of addition Nb and Ti
The Cr element for preventing crystal boundary carbon from quickly spreading inhibits the generation of high temperature pro-eutectoid crystal boundary ferrite net, fundamentally solves
This technical problem；Simultaneously because Nb, Ti microalloy technology have effectively refined austenite grain in high-temperature heating process, because
This is obtained with good ultrafine-grained (UFG) microstructure in Rolling production, without Conventional cryogenic controlled rolling technique；This skill
Art advantage can not carry out low temperature rolling type steel production line in particular for Hot Metal in Beam Blank such as H profile steel rolling etc., produce for improving
Product properties of product have huge technology and economic value.
The purpose of the present invention is mainly achieved through the following technical solutions:
A kind of low temperature resistant micro alloyed steel, the chemical composition comprises the following components in percentage by weight of the micro alloyed steel are as follows: C:
0.075%~0.1%；Si:0.10%~0.30%；Mn:1.0%~1.40%；Cr:0.25%~0.50%；Nb:
0.020%~0.030%；Ti:0.015%~0.025%；Al :≤0.015%；P :≤0.010%；S :≤0.010%；It is remaining
Amount is Fe and inevitable impurity element；The inevitable impurity element includes gas content and other are inevitable
Impurity element, the gas content: molten steel [H]≤2.0ppm, slab [H]≤2ppm, [O]≤30ppm, [N]≤50ppm；Institute
State other inevitable impurity element≤1%.
The present invention has the beneficial effect that:
The present invention ensure that autstenitic grain size exists by the micro alloyed steel fine grain effect of the Nb+Ti in mild steel
It is effectively controlled under the conditions of 1200 DEG C, lays a good foundation to obtain fine grained texture for the hot rolling of steel routine.Generally use Nb+
The fine grain effect of V micro alloyed steel is far below the microalloying fine grain effect of Nb+Ti, is not able to satisfy -60 DEG C of low temperature requirements, especially
It is when producing large scale specification product, it is necessary to just can solve surface to center portion using the microalloying fine grain technique of Nb+Ti
The whole crystal grain refinement of steel.
The effect of each element and proportion foundation in micro alloyed steel are as follows:
Carbon: the basic element of the low-carbon low-alloy steel based on ferrite-pearlite；Phosphorus content is 0.08%~0.17%
When being cooled to 1495 DEG C from liquid phase peritectic reaction occurs for carbon steel, continuous casting billet brought by the negative effect in order to avoid peritectic reaction
Surface transverse cracks phenomenon, C content is as low as possible, but is likely to occur low-carbon shellfish in the too low increase and decrease and steel that will cause production cost
Family name's body tissue phenomenon, therefore C content of the present invention is selected as C:0.075~0.1%.
Silicon: being non-carbide forming element, be mainly present in steel with solution, there is significant solution strengthening effect,
It can be significantly reduced austenite-ferrite rate of transformation, improve austenite self-diffuse activation energy, reduce self-diffusion coefficient, it can be with
Play the role of inhibiting C diffusion velocity；Under the premise of compared with big supercooling degree, it is brighter to postpone austenite-ferrite transformation effect
It is aobvious, to have refinement pearlite lamella effect, but excessive Si will deteriorate the toughness of steel in continuous cooling process；It is comprehensive
Above-mentioned consideration, steel Si content range of the present invention are 0.10~0.30%.
Manganese: being weak carbide formation element, there is slight segregation phenomena in Casting Billet of Highcarbon Steel, and expands austenitic area member
Element, the strong stability for improving overcooling austenite postpone austenite-ferrite transformation, while being also to reduce perlitic transformation temperature
Degree extends pearlite incubation period, close with Cr element interaction, is the strong element for postponing perlitic transformation, while having reduction
The effect of eutectoid carbon content；Weak carbide formation element forms alloy carbide or alloyed cementite in perlitic transformation,
Therefore diffusion and redistribution of the carbon in austenite are not only needed, but also needs carbide former in austenite
Diffusion and redistribution, to significantly postpone pearlitic transformation；The diffusion coefficient of C is than replacing solid solution element such as in austenite
The atomic diffusivities such as Mn, Cr big 5 several magnitudes, therefore Mn is able to suppress the generation of pearlite.Mn element can improve steel
Harden ability, have certain solution strengthening effect；In addition, there are also the effects for controlling field trash by Mn.But when Mn too high levels,
Segregation in slab, which is inclined to, to be increased, and the uniformity of tissue is reduced, to reduce drawing property.For these reasons, of the invention
Steel Mn content range are as follows: 1.0~1.40%.
Niobium: being carbide, exists in steel with carbide or carbonitride form, low-carbon microalloyed
Play the role of strong fine grain in steel, while solution strengthening, precipitation strength are also fairly obvious, but due in austenite
Crystal boundary is precipitated, and promotes the generation of austenite grain boundary ferrite net, significantly weakens austenite grain boundary, leads to continuous casting transverse crack
Generation, experimental analysis shows that Nb bearing steel transverse crack is grain boundary fracture, and crystal boundary is that have ferrite net appearance, therefore need
Inhibit the generation of crystal boundary ferrite net.The present invention is effectively to inhibit C in Ovshinsky by adding a certain number of Cr elements
Diffusion velocity in body, and then prevent the generation of crystal boundary pro-eutectoid ferrite.According to refined crystalline strengthening effect, steel Nb of the present invention contains
Amount is 0.020~0.030%.
Titanium: the TiC particle of a large amount of Dispersed precipitates formed during solidification of molten steel can become brilliant when solidification of molten steel
Core refines structure of steel, reduces the generation of coarse column crystal and dendritic structure conducive to the crystallization of steel, and can reduce segregation reduces band
Shape tissue rank is the powerful technique measure of low-carbon low-alloy steel crystal grain refinement；In addition, Ti can also be generated in conjunction with N it is stable
High diffusive compound, the carbide binding force that Ti and C is formed is extremely strong, it is extremely stable, be not easily decomposed, TiC particle, which has, prevents steel Ovshinsky
Body crystal grain is grown up the effect of roughening；Ti can also generate the carbide particle of indissoluble with Fe and C, be enriched in the crystal boundary of micro alloyed steel
Place, prevents the grain coarsening of steel, and Ti can also dissolve in austenite and ferrite, forms solid solution, and steel is made to generate reinforcing.Due to Ti
(CN) identical with Nb (CN) lattice structure, thus Nb (CN) be precipitated when with Ti (CN) be forming core core be precipitated, form compound carbon
Nitrogen precipitated phase.Ti content of the present invention are as follows: 0.015~0.025%.
Chromium: being weak carbide formation element, and Cr promotes cementite unstability and M2C is formed, and small and dispersed precipitating is formed, through heat
Machine software and the experimental results showed that, within the scope of 0.40~0.80wt.%, not Cr carbide generate and center only
There is the segregation of very little index.The comprehensive function of Cr is close with Mn element, significantly reduces eutectoid carbon content, strongly obstruction austenite-
Ferrite transformation, while perlitic transformation is postponed strongly, stable austenite element, austenite can be reduced significantly by improving its content
Phase region；With the harden ability for improving steel, while Cr can refine pearlite piece interlamellar spacing, can be improved wire rod in drawing process
Work hardening rate guarantees high-intensitive.Steel Cr content range of the present invention are as follows: Cr:0.25~0.50%.
Aluminium, p and s: impurity element in steel significantly reduces plasticity and toughness and welding performance, is not causing other influences situation
Under, more lower better, aluminium is used for deoxidation, therefore range Al :≤0.015%, and p and s content controls within 0.01wt.%, i.e.,
Al :≤0.015%；P :≤0.010%；S :≤0.010%.
On the basis of above scheme, the present invention has also done following improvement:
Further, C content is 0.081%~0.093% in the low temperature resistant micro alloyed steel.
Preferably, C content is 0.085%~0.090% in the low temperature resistant micro alloyed steel.
Further, Si content is 0.13%~0.25% in the low temperature resistant micro alloyed steel.
Preferably, Si content is 0.18%~0.21% in the low temperature resistant micro alloyed steel.
Further, Mn content is 1.08%~1.36% in the low temperature resistant micro alloyed steel.
Preferably, Mn content is 1.13%~1.22% in the low temperature resistant micro alloyed steel.
Further, Cr content is 0.28%~0.43% in the low temperature resistant micro alloyed steel.
Preferably, Cr content is 0.31%~0.37% in the low temperature resistant micro alloyed steel.
Further, Nb content is 0.022%~0.028% in the low temperature resistant micro alloyed steel.
Further, Ti content is 0.017%~0.023% in the low temperature resistant micro alloyed steel.
Further, the microstructure of the low temperature resistant micro alloyed steel is ferrite and pearlite.
Further, the low temperature resistant micro alloyed steel is applied under the conditions of limiting temperature is -60 DEG C, described low temperature resistant micro-
The thickness of alloying steel is in 20mm or more.
The low temperature resistant micro alloyed steel of the present invention is used for extremely cold area steel building steel, realizes from low temperature to high and cold steel
It uses.
Further, the low temperature resistant microalloying steel surface and center portion grain size range are controlled at 10 grades or more.
Low temperature resistant microalloying steel surface and center portion grain size range are controlled at 10 grades or more by the present invention, ensure that
Steel ballistic work under the conditions of -60 DEG C is greater than 27J.
A kind of production technology of low temperature resistant micro alloyed steel, comprising: converter smelting → LF furnace or RH furnace refining → slab or H
Steel casting for shaped blank continuous → heating stove heating → steel plate or H profile steel rolling line；
The heating stove heating: heating temperature range is 1200 DEG C~1240 DEG C；
The steel plate or H profile steel rolling line: start rolling temperature is controlled at 1100 DEG C~1200 DEG C, is rolled into finishing mill temperature
Degree control is rolled rear air-cooled at 890 DEG C~910 DEG C.
Resistance to -60 DEG C of low temperature micro alloyed steel of the present invention, for large scale think gauge steel plate or H profile steel thickness (20mm with
On), low temperature impact properties, the especially crystalline substance of center portion performance cannot be guaranteed using Nb+V combined microalloying+air-cooled technique of control
Particle size；Using Nb+Ti combined microalloying, the carbonitride of Ti is taken full advantage of the liquid forming core the characteristics of, makes austenite
Crystal grain has just obtained more adequately refinement under the conditions of as-cast structure, it is suppressed that columanar structure grows up, and obtains more
Uniform equiaxed grain structure inhibits component segregation；Growing up for austenite grain is inhibited in 1200 DEG C or less precipitations using Nb,
Therefore the low temperature resistant micro alloyed steel haveing excellent performance can both be obtained using above-mentioned production technology.
Further, the heating furnace heating temperature range is 1215 DEG C~1233 DEG C.
Further, the start rolling temperature control is rolled and is controlled into finishing mill temperature at 895 DEG C at 1131 DEG C~1189 DEG C
~906 DEG C.
The invention has the benefit that
(1) micro alloyed steel of the present invention is to use steel with fine grain is low temperature resistant for -60 DEG C of low temperature, on the one hand, passes through low-alloy
Nb, Ti microalloy element are added in steel, make effectively to have refined austenite grain in Rolling production, and then finally refined ferrite
Pearlitic structrure makes the steel grade can satisfy the requirement of -60 DEG C of conditions of low temperature；On the other hand, pass through the excellent of alloy system
Change design, solves Nb micro alloyed steel steel billet crystal boundary ferrite net and generate core technology problem, i.e., so-called continuous casting billet plasticity
The control problem in low ebb area, and then effectively control the technical problem that casting billet surface is easy to produce transverse crack；
(2) the low-alloy steel kind such as alloy system production continuous casting H profile steel of the present invention, slab, square billet, it is special without taking
Continuous casting manufacturing technique, such as: the depth that reduction continuous casting secondary cooling water, control crystallizer vibration reduce oscillation mark trough is big, special tune
Whole continuous casting billet pulling rate；
(3) low temperature resistant -60 DEG C of present invention exploitation with low-alloy steel, is mainly used for extremely cold area steel building steel, leads to
The micro-alloying technology for crossing Nb+Ti effectively controls growing up for austenite grain in steel rolling heating process, final to obtain iron element
Body-pearlite superfine grained structure, grain size reach 9 grades or more, meet the technical requirements of low temperature indices；The present invention is micro-
Yield strength > 355MPa of alloying steel；Tensile strength > 550MPa；- 60 DEG C of low-temperature impact Ak > 27J；Elongation after fracture >
22%.
It in the present invention, can also be combined with each other between above-mentioned each technical solution, to realize more preferred assembled schemes.This
Other feature and advantage of invention will illustrate in the following description, also, certain advantages can become from specification it is aobvious and
It is clear to, or understand through the implementation of the invention.The objectives and other advantages of the invention can be by written specification, right
Specifically noted structure is achieved and obtained in claim and attached drawing.
Detailed description of the invention
Attached drawing is only used for showing the purpose of specific embodiment, and is not to be construed as limiting the invention, in entire attached drawing
In, identical reference symbol indicates identical component.
Fig. 1 is the formation schematic diagram of NbC crystal boundary precipitation and crystal boundary ferrite net；
Fig. 2 is Nb micro-alloying low-carbon H steel continuous casting billet surface transverse cracks sterogram；
Fig. 3 is Nb micro-alloying low-carbon H steel continuous casting billet surface transverse cracks schematic diagram；
Fig. 4 is micro-organization chart at Nb micro-alloying low-carbon H steel continuous casting billet surface transverse cracks；
Fig. 5 is the micro-organization chart of 1# micro alloyed steel of the present invention；
Fig. 6 is the micro-organization chart of comparative example micro alloyed steel of the present invention.
Specific embodiment
Specifically describing the preferred embodiment of the present invention with reference to the accompanying drawing, wherein attached drawing constitutes the application a part, and
Together with embodiments of the present invention for illustrating the principle of the present invention, it is not intended to limit the scope of the present invention.
A specific embodiment of the invention, discloses a kind of low temperature resistant micro alloyed steel, the change of the micro alloyed steel
It studies point by weight percentage are as follows: C:0.075%~0.1%；Si:0.10%~0.30%；Mn:1.0%~1.40%；
Cr:0.25%~0.50%；Nb:0.020%~0.030%；Ti:0.015%~0.025%；Al :≤0.015%；P :≤
0.010%；S :≤0.010%；Surplus is Fe and inevitable impurity element；The inevitable impurity element includes gas
Body content and other inevitable impurity elements, the gas content: molten steel [H]≤2.0ppm, slab [H]≤2.0ppm,
[O]≤20ppm, [N]≤50ppm；Other described inevitable impurity element≤1%.
In another embodiment, in the low temperature resistant micro alloyed steel of the present invention C content be 0.081%~
0.093%.
In another embodiment, in the low temperature resistant micro alloyed steel of the present invention C content be 0.085%~
0.090%.
In another embodiment, in the low temperature resistant micro alloyed steel of the present invention Si content be 0.13%~
0.25%.
In another embodiment, in the low temperature resistant micro alloyed steel of the present invention Si content be 0.18%~
0.21%.
In another embodiment, in the low temperature resistant micro alloyed steel of the present invention Mn content be 1.08%~
1.36%.
In another embodiment, in the low temperature resistant micro alloyed steel of the present invention Mn content be 1.13%~
1.22%.
In another embodiment, in the low temperature resistant micro alloyed steel of the present invention Cr content be 0.28%~
0.43%.
In another embodiment, in the low temperature resistant micro alloyed steel of the present invention Cr content be 0.31%~
0.37%.
In another embodiment, in the low temperature resistant micro alloyed steel of the present invention Nb content be 0.022%~
0.028%.
In another embodiment, in the low temperature resistant micro alloyed steel of the present invention Ti content be 0.017%~
0.023%.
In another embodiment, the microstructure of the low temperature resistant micro alloyed steel of the present invention includes ferrite and pearl
Body of light.
In another embodiment, the low temperature resistant micro alloyed steel limits of application temperature range of the present invention is -60 DEG C,
The thickness of the low temperature resistant micro alloyed steel is in 20mm or more.
In another embodiment, the low temperature resistant micro alloyed steel surface layer of the present invention and center portion grain size range are
10 grades of grain size refinement levels or more.
In another embodiment, a kind of production technology of low temperature resistant micro alloyed steel of the present invention, comprising: converter
Smelting → LF furnace or RH furnace refining → slab or H steel casting for shaped blank continuous → heating stove heating → steel plate or H profile steel Rolling Production
Line；
The heating stove heating: heating temperature range is 1200 DEG C~1240 DEG C；
The steel plate or H profile steel rolling line: start rolling temperature is controlled at 1100 DEG C~1200 DEG C, is rolled into finishing mill temperature
Degree control is rolled rear air-cooled at 890 DEG C~910 DEG C.
In another embodiment, heating furnace heating temperature range of the present invention is 1215 DEG C~1233 DEG C.
In another embodiment, start rolling temperature control of the present invention is rolled at 1131 DEG C~1189 DEG C into finish rolling
Machine temperature is controlled at 895 DEG C~906 DEG C.
In another embodiment, the present invention provides the chemical component of micro alloyed steel and comparative example, and to it
Mechanical property, low temperature impact properties and crystallite dimension are tested, and Tables 1 and 2 is specifically shown in.
The chemical component (wt%) of 1 micro alloyed steel of table and comparative example
Mechanical property, low temperature impact properties and the grain size of 2 micro alloyed steel of table and comparative example
Wherein, comparative example alloy system and production technology are as follows: percentage composition (wt.%) counts chemical component by weight are as follows: C:
0.09~0.12%；Si:0.10~0.30%；Mn:1.0~1.40%；V:0.04~0.08%；Nb:0.020~0.030%；
Al :≤0.020%；P :≤0.010%；S :≤0.010%；Gas content: molten steel [H]≤2.0ppm, slab [H]≤
2.0ppm, [O]≤30ppm, [N]≤50ppm；Other inevitable impurity element≤1%, remaining is Fe.Its production technology
It is through converter smelting → LF furnace or RH furnace refining → slab or H steel casting for shaped blank continuous → heating stove heating → steel plate or H profile steel
Rolling line；H profile steel production technology: the heating temperature of heating furnace is 1200 DEG C~1240 DEG C, and start rolling temperature is controlled 1100
~1200 DEG C, rolled piece, at 890~910 DEG C, rolls rear air-cooled into finishing mill temperature.
Plate Production technique: the heating temperature of heating furnace is 1200 DEG C~1240 DEG C, start rolling temperature control 1100~
1200 DEG C, rolled piece, at 800~900 DEG C, rolls rear section cooling to 600 ± 15 DEG C into finishing mill temperature, air-cooled to arrive room temperature.
Emphasis needs to solve the problems, such as crystal grain refinement in low-alloy system of the invention, so that better low-temperature flexibility is obtained,
Simultaneously in the metallurgical technology of refinement crystal grain, it is necessary to use micro-alloying technology and Controlled Rolling And Controlled Cooling.Micro-alloying low-carbon is low
Steel alloy technology faces the transverse fissure control problem that big technical problem emphatically is continuous casting billet, the main reason is that, peritectic reaction and micro-
The negative effect of crystal boundary ferrite net, causes the transverse crack of casting billet surface to occur caused by alloying element crystal boundary is precipitated.Specifically
It is analyzed as follows:
Peritectic reaction mechanism: when being cooled to 1495 DEG C from liquid phase peritectoid occurs for the carbon steel that phosphorus content is 0.08%~0.17%
Reaction, δ Fe (solid)+L (liquid) → γ Fe (solid), traditionally carbon steel of the phosphorus content within the scope of this is referred to as peritectic reaction
Steel.When since δ Fe+L → γ Fe transformation occurs, linear contractive quotiety is 9.8 × 10-5/ DEG C, and the δ Fe line of peritectic reaction does not occur
Constriction coefficient is 2 × 10-5/℃.Therefore linear shrinkage amount is larger when peritectic reaction, green shell and crystallizer wall air gap easy to form,
Being prematurely formed for air gap will lead to contraction unevenness and shell thickness unevenness, in weakness crackle easy to form, be easy to happen bleed-out
Accident and cc billet surface quality defect, therefore mild steel is one of the steel grade of more difficult continuous casting in continuous casting.
Based on above-mentioned analysis, carbon content control of the present invention is in 0.075~0.1% range, and small packet crystalline substance reacts as far as possible
Counter productive.
Ferrite net generates: the negative effect of Nb micro alloyed steel is that crystal boundary is precipitated mechanism and induces the netted iron of crystal boundary
Ferritic generates.Although crystal boundary precipitation particles can play the role of pinning austenite grain boundary, make crystal boundary net as nucleation mass point
The generation of columnar ferrite, weakens grain-boundary strength, and macro manifestations are the plasticity low ebb for larger temperature range occur, subsequent slab
Cause transversal crack during straightening, sees Fig. 1.The stain to form a line among Fig. 1 indicates crystal boundary Nb precipitation particles, surrounding string-like
There is micro-crack after indicating crystal boundary stress, two sides blank space indicates that grain boundary ferrite is precipitated to string-like up and down, and upper and lower two sides solid matter is black
Point indicates prior austenite body tissue, and arrow indicates Impact direction.
Technical measures of the present invention by addition Cr element, effective solution crystal boundary ferrite net forming core and development,
So as to avoid the generation of crystal boundary ferrite net, control slab transverse crack.
Utilization of the present invention to above-mentioned two big metallurgical mechanisms, the technology for effectively meeting intensity, toughness and surface quality refer to
Target requirement, obtains excellent cryogenic property.
It as shown in Figure 2,3, 4, is Nb micro-alloying low-carbon H steel continuous casting billet surface transverse cracks and cracks microstructure；Fig. 5
For the micro-organization chart of 1# steel of the present invention, Fig. 6 is the micro-organization chart of comparative example of the present invention, and You Tuzhong is, it can be seen that the present invention
1# steel leads to the generation of grain boundary ferrite and the generation of surface layer crackle because of the addition of Nb.
Its technical solution is the Cr for preventing ferrite from generating by addition, it is suppressed that the netted grain boundary ferrite in surface layer
It generates, to solve the generation of the phenomenon that surface transverse cracks caused by Nb microalloying.
It is noted that the principle of production technology of the present invention are as follows: resistance to low -60 DEG C warm low-alloy steel of the present invention, for big ruler
The steel plate or H profile steel thickness (20mm or more) of very little think gauge cannot be guaranteed using Nb+V combined microalloying+air-cooled technique of control
Low temperature impact properties, the especially crystallite dimension of center portion performance.Using Nb+Ti combined microalloying, the carbon of Ti is taken full advantage of
Nitride makes austenite grain just obtain more adequately refinement, suppression under the conditions of as-cast structure the liquid forming core the characteristics of
Zhi Liao columanar structure grows up, and obtains more uniform equiaxed grain structure, inhibits component segregation.Using Nb at 1200 DEG C
Be precipitated below and inhibit growing up for austenite grain, thus can both be obtained using conventional hot rolling technology have excellent performance it is low temperature resistant
Steel.
In conclusion the present invention provides a kind of low temperature resistant micro alloyed steels and its production technology, the present invention to develop resistance to
- 60 DEG C of low temperature of micro alloyed steel is mainly used for extremely cold area steel building steel；Meanwhile the present invention passes through the micro- of Nb+Ti
Alloying process effectively controls growing up for austenite grain in steel rolling heating process, and final acquisition ferrite-pearlite is ultra-fine
Grain structure, grain size reach 9 grades or more, meet the technical requirements of low temperature indices, and the yield strength of micro alloyed steel >
355MPa；Tensile strength > 550MPa；- 60 DEG C of low-temperature impact Ak > 27J；Elongation after fracture > 22%.
The foregoing is only a preferred embodiment of the present invention, but scope of protection of the present invention is not limited thereto,
In the technical scope disclosed by the present invention, any changes or substitutions that can be easily thought of by anyone skilled in the art,
It should be covered by the protection scope of the present invention.
Claims (9)
1. a kind of low temperature resistant micro alloyed steel, which is characterized in that the chemical composition comprises the following components in percentage by weight of the micro alloyed steel
Are as follows: C:0.075%~0.1%；Si:0.10%~0.30%；Mn:1.0%~1.40%；Cr:0.25%~0.50%；Nb:
0.020%~0.030%；Ti:0.015%~0.025%；Al :≤0.015%；P :≤0.010%；S :≤0.010%；It is remaining
Amount is Fe and inevitable impurity element；The inevitable impurity element includes gas content and other are inevitable
Impurity element, the gas content: molten steel [H]≤2.0ppm, slab [H]≤2ppm, [O]≤30ppm, [N]≤50ppm；Institute
State other inevitable impurity element≤1%；
The production technology of the low temperature resistant micro alloyed steel, comprising: converter smelting → LF furnace or RH furnace refining → slab or H steel are used
Casting for shaped blank continuous → heating stove heating → steel plate or H profile steel rolling line；
The heating stove heating: heating temperature range is 1200 DEG C~1240 DEG C；
The steel plate or H profile steel rolling line: start rolling temperature is controlled at 1100 DEG C~1200 DEG C, is rolled into finishing mill temperature control
System is rolled rear air-cooled at 890 DEG C~910 DEG C；
The low temperature resistant micro alloyed steel is applied under the conditions of limiting temperature is -60 DEG C；
The production technology of the low temperature resistant micro alloyed steel does not include reduction continuous casting secondary cooling water, control crystallizer vibration reduction
Oscillation mark；
The microstructure of the low temperature resistant micro alloyed steel is ferrite and pearlite.
2. a kind of low temperature resistant micro alloyed steel according to claim 1, which is characterized in that the low temperature resistant micro alloyed steel
It is 0.13%~0.25%, Mn content is that 1.08%~1.36%, Cr contains that middle C content, which is 0.081%~0.093%, Si content,
It is 0.022%~0.028%, Ti content is 0.017%~0.023% that amount, which is 0.28%~0.43%, Nb content,.
3. a kind of low temperature resistant micro alloyed steel according to claim 1, which is characterized in that the low temperature resistant micro alloyed steel
Middle C content is that 0.085%~0.090%, Si content is 0.18%~0.21%.
4. a kind of low temperature resistant micro alloyed steel according to claim 1, which is characterized in that the low temperature resistant micro alloyed steel
Middle Mn content is that 1.13%~1.22%, Cr content is 0.31%~0.37%.
5. a kind of low temperature resistant micro alloyed steel according to claim 1, which is characterized in that the low temperature resistant micro alloyed steel
Thickness in 20mm or more.
6. a kind of low temperature resistant micro alloyed steel according to claim 1, which is characterized in that the low temperature resistant micro alloyed steel
Surface and center portion grain size range are controlled at 10 grades or more.
7. a kind of production technology of low temperature resistant micro alloyed steel, which is characterized in that be used to prepare such as any one of claim 1-6 institute
The low temperature resistant micro alloyed steel stated, the production technology include: converter smelting → LF furnace or RH furnace refining → slab or H steel with different
Parison continuous casting → heating stove heating → steel plate or H profile steel rolling line；
The heating stove heating: heating temperature range is 1200 DEG C~1240 DEG C；
The steel plate or H profile steel rolling line: start rolling temperature is controlled at 1100 DEG C~1200 DEG C, is rolled into finishing mill temperature control
System is rolled rear air-cooled at 890 DEG C~910 DEG C；
The production technology of the low temperature resistant micro alloyed steel does not include reduction continuous casting secondary cooling water, control crystallizer vibration reduction
Oscillation mark.
8. a kind of production technology of low temperature resistant micro alloyed steel according to claim 7, which is characterized in that heating stove heating
Temperature range is 1215 DEG C~1233 DEG C.
9. a kind of production technology of low temperature resistant micro alloyed steel according to claim 7, which is characterized in that the open rolling temperature
Degree control is rolled and is controlled into finishing mill temperature at 895 DEG C~906 DEG C at 1131 DEG C~1189 DEG C.
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| JP2002363642A (en) * | 2001-06-01 | 2002-12-18 | Nkk Corp | Method for producing rolled wide flange shape having low yield ratio and excellent toughness |
| CN103834861A (en) * | 2014-03-20 | 2014-06-04 | 莱芜钢铁集团有限公司 | 320MPa low-temperature resistant hot-rolled H-shaped steel and preparation method thereof |
| CN104862588A (en) * | 2015-06-03 | 2015-08-26 | 马钢(集团)控股有限公司 | Hot-rolled H-shaped profile steel and production method thereof |
| JP2015218360A (en) * | 2014-05-16 | 2015-12-07 | 新日鐵住金株式会社 | Rolled steel and production method therefor |
| JP2016079443A (en) * | 2014-10-15 | 2016-05-16 | 新日鐵住金株式会社 | High strength extra thick h-shaped steel excellent in toughness and production method therefor |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2002363642A (en) * | 2001-06-01 | 2002-12-18 | Nkk Corp | Method for producing rolled wide flange shape having low yield ratio and excellent toughness |
| CN103834861A (en) * | 2014-03-20 | 2014-06-04 | 莱芜钢铁集团有限公司 | 320MPa low-temperature resistant hot-rolled H-shaped steel and preparation method thereof |
| JP2015218360A (en) * | 2014-05-16 | 2015-12-07 | 新日鐵住金株式会社 | Rolled steel and production method therefor |
| JP2016079443A (en) * | 2014-10-15 | 2016-05-16 | 新日鐵住金株式会社 | High strength extra thick h-shaped steel excellent in toughness and production method therefor |
| CN104862588A (en) * | 2015-06-03 | 2015-08-26 | 马钢(集团)控股有限公司 | Hot-rolled H-shaped profile steel and production method thereof |
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