CN107988565B - A kind of high toughness high hardenability high speed axle steel and its heat treatment method - Google Patents
A kind of high toughness high hardenability high speed axle steel and its heat treatment method Download PDFInfo
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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
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/54—Ferrous alloys, e.g. steel alloys containing chromium with nickel with boron
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- 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
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/18—Hardening; Quenching with or without subsequent tempering
-
- 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
- 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
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
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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
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
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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
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
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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
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/46—Ferrous alloys, e.g. steel alloys containing chromium with nickel with vanadium
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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
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/48—Ferrous alloys, e.g. steel alloys containing chromium with nickel with niobium or tantalum
-
- 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
- C21D2211/001—Austenite
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- 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
- C21D2211/008—Martensite
Abstract
A kind of high toughness high hardenability high speed axle steel, the yield strength R of the axle steelp0.2>=630MPa, tensile strength Rm >=800MPa, elongation percentage A >=20%, 5mm notch room temperature impact of collision absorb function KU2>=80J, ductile-brittle transition temperature are lower than -40 DEG C；The chemical component of the steel includes B, and the B is 0.0008~0.0025% by weight percentage.The present invention also provides the preparation methods of the steel simultaneously.The present invention gives full play to effect of each element in axle steel, obtains that crystal grain is tiny and microscopic structure based on martensite.The martensitic structure of uniform fine grain austenite grain and the enhancing of Nb microalloy nano-second-phase can be obtained using the heat treatment of quenching+high tempering twice, it realizes high-intensitive, high tenacity and high-hardenability excellent matching, finally makes high speed axle that there is the military services such as good shock resistance, antifatigue performance, excellent obdurability matching and good harden ability.
Description
Technical field
The present invention relates to railcar axle-steel technical field more particularly to a kind of fine grains, high-strength tenacity and high-hardenability
High speed axle steel and its heat treatment method.
Background technique
Axle is most harsh one of the component of rail transit train service condition, bears the self weight of train almost all and bears
Lotus.With putting into operation for China express railway, train speed is further increased, so that axle dynamic loading is continuously increased, to vehicle
The safety and reliability of axis brings very big challenge, and to the performance of axle material, more stringent requirements are proposed.Due to various countries
National conditions are broadly divided into two major classes with technical thought difference, the axle material of each railway developed country high-speed railway in the world: in high-quality
Carbon steel and high strength alloy steel.If modern architecture in Japan high-speed railway axle generallys use carbon steel (S38C), using
Surface mid frequency induction hardening heat treatment process, complex process are high to the technology controlling and process level requirement of equipment and personnel；European high-speed railway
Axle material then mostly uses greatly low-alloy structural steel (such as EA4T), 0.90-1.20wt.% containing Cr, Mo 0.15-0.30wt.%,
It can be obtained respective organization and performance by traditional Tempering and Quenching mode, but since this steel alloy content is lower, it is big to cut
There is harden ability deficiency in face axle, axle section structure and performance are uneven, influence its overall performance；The high iron car in Europe
Shaft material small part selects 30NiCrMoV12 medium alloy constructional steel, in steel containing 0.60~1.00wt.% of Cr, Ni 2.70~
0.40~0.60wt.% of 3.30wt.%, Mo, V0.08~0.13wt.%, such steel grade harden ability is good, can oil quenching, hardness it is high,
Corrosion resistance and good, but cost is higher.Horizontal and axle manufacturing enterprise actual heat treatment is smelted according to the current steel billet in China
The technology road of alloying Tempering and Quenching has preferentially been selected in technological equipment situation, the development for the high-speed train axle that domesticizes
Line.Chinese patent 201410532111.7 provides a kind of axle steel, on the basis of EA4T steel chemical composition, by adding Nb
0.015~0.060wt.%, B0.0008~0.0050wt.%, the harden ability of Lai Tigao steel, but due to not adopting an effective measure
The N in steel is fixed, part B can generate BN in conjunction with N more than needed, so that its effect for improving harden ability falls flat,
Meanwhile BN precipitation size is larger, the crystallite dimension for also easily leading to steel is uneven, reduces the service performance of axle.
Summary of the invention
In view of the above analysis, the present invention is intended to provide the high speed of boron containing niobium of a kind of fine grain, high tenacity and high-hardenability arranges
Vehicle axles steel.In chemical component, use in low C, the Alloying Design based on Cr, Ni, using high Nb, micro- V, Mo cooperate with
Multi-element composite micro-alloying thinking, it is preferred that emphasis is the Proper Match of C, Nb, V, Mo, Cr element gives full play to it in axle steel
In effect, obtain that crystal grain is tiny and microscopic structure based on martensite, guarantee the through hardening of axle steel furthermore with the B of solid solution
Property is not reduced due to crystal grain refinement and NbC are precipitated, make axle steel that there is high intensity, high tenacity, high-hardenability etc. to integrate mechanical property
Energy, to have good shock resistance and antifatigue equal military services performance.
The purpose of the present invention is mainly achieved through the following technical solutions:
A kind of high toughness high hardenability high speed axle steel, the yield strength R of the axle steelp0.2>=630MPa, tension
Intensity Rm >=800MPa, elongation percentage A >=20%, 5mm notch room temperature impact of collision absorb function KU2>=80J, ductile-brittle transition temperature are low
In -40 DEG C；The chemical component of the steel includes B, and B is 0.0008~0.0025% by weight percentage.
Further, the chemical component of the steel is C:0.24~0.32% by weight percentage, Si:0.20~
0.40%, Cr:0.90~1.20%, Mn:0.60~0.90%, V:0.00~0.06%, Nb:0.08~0.12%, Ni:
0.50~1.50%, Mo:0.20~0.30%, Alt:0.020~0.040%, P: < 0.010%, S: < 0.010%, O: <
0.0015%, N: < 0.008%, remaining is Fe and inevitable impurity.
Further, in the tissue of the axle steel average grain size of austenite grain less than 12 μm.
The present invention also provides a kind of preparation methods of high toughness high hardenability high speed axle steel, using converter, electricity
Furnace or vacuum induction furnace smelting, continuous casting or molding after external refining, slab is air-cooled after forging rolling through the laggard driving axis forging rolling of cogging,
It is heat-treated, obtains high toughness high hardenability high speed axle steel.
Further, the heating temperature of forging rolling is 1150~1250 DEG C, and finish-forging and finishing temperature are not less than 850 DEG C
Austenite is decomposed phase transformation when to avoid forging rolling, and finish-forging and finishing temperature are not less than 850 DEG C, air-cooled after forging rolling,
Tiny austenite grain and excellent obdurability matching can be obtained using the heat treatment of quenching+high tempering twice.
Further, after the heat treatment is specifically, the steel after forging rolling carries out quenching heat treatment twice in hardening media,
Tempering is carried out again, obtains the axle steel.
Further, carry out first time quenching heat treatment temperature be 900~950 DEG C, the heating and thermal insulation time be 10~
60min。
Further, carry out second of quenching heat treatment temperature be 850~900 DEG C, the heating and thermal insulation time be 30~
120min。
First time hardening heat selects 900~950 DEG C of progress austenitizings of higher temperature, it is therefore an objective to eliminate forging or rolling
Heterogeneous structure, while parts back dissolving and the homogenization such as make V, Nb, the heat preservation of 10~60min of short period is to inhibit difficult to understand
Family name's body crystal grain and the roughening that MX particle (M:V, Nb, X:C, N) particle has been precipitated, rapid cooling are martensite/bayesian in order to obtain
Body tissue, while MX being inhibited to be precipitated in cooling high temperature section.
In first time, quenching is obtained on more uniform tiny martensite organization foundation, and second of hardening heat selection is compared with low temperature
850-900 DEG C of degree carries out secondary austenitizing, mainly obtains more nanometer MX particles, and reduce AUSTENITE GRAIN COARSENING and incline
To thus soaking time can also extend to 120min, final to obtain uniformly tiny austenite grain and its phase-change organization.
Further, the temperature of tempering is 620~680 DEG C, soaking time 3~8 hours, air-cooled after tempering to arrive room
Temperature.
Further, which is characterized in that the hardening media is water, water mist or oil.
The effect of each element of the present invention and proportion are according to as follows:
Carbon: most important intensified element and one of the element for improving harden ability, to guarantee enough intensity and harden ability, C
Content must be in 0.24wt.% or more；But when C content is higher than 0.32wt.%, the plasticity and toughness of steel can be significantly reduced, therefore
It is 0.24~0.32wt.% that the present invention, which controls C content,.
Silicon: solution strengthening effect is significant but damages toughness also significant alloying element, while being also main deoxidation in steel
Element.Therefore, the present invention mainly utilizes its deoxidation, and it is 0.20~0.40wt.% that control Si content, which is reduced levels,.
Manganese: the effective element of deoxidization desulfuration, while being also the element for guaranteeing harden ability.But similar with Si, Mn content is more than
The toughness of steel can be significantly reduced when 0.90wt.%, Mn content is too low then effectively deoxidization desulfuration and cannot to guarantee the harden ability of steel.Cause
This, it is 0.60~0.90% that the present invention, which controls Mn content,.
Chromium: moderate Cr is added in steel of the present invention can not only significantly improve the harden ability of steel, moreover it is possible to improve material structure
Uniformity.(Fe, Cr) is formed when Cr is dissolved in cementite3When C alloy cementite, the work of refinement crystal grain and cementite can be played
With being improved the obdurability of material to obtain uniformly tiny quenching crystal grain and tempered structure.But excessive Cr and C
Cr easy to form7C3Equal carbide, damage toughness, the plasticity of steel.Therefore, the present invention control Cr content be 0.90~
1.20wt.%.
Nickel: improve the most effective alloying element of steel toughness, cda alloy cost and its with other alloying elements tough
Property, the collaboration in terms of harden ability, the content of Ni is controlled in 0.50~1.50wt.% in steel of the present invention.
Molybdenum: the present invention obtains tiny austenite grain, significant nano-second-phase by Mo, Nb, V combined microalloying
Precipitation strengthening effect and high resistance to tempering, it is hereby achieved that fine grain, high tenacity high tempering tissue.In addition, Mo with
The rational proportion of the alloying elements such as Cr, Ni and C, V can obtain good harden ability under fine austenite crystalline form.Mo
Content is lower than 0.20, and above-mentioned effect is limited, too high levels, then above-mentioned effect saturation even result in improve resistance to tempering make it is used
It is surplus, the alloy and tempering heat treatment process cost of steel will be improved.Therefore, the present invention controls 0.20~0.30wt.% of Mo content.
Niobium: steel of the present invention be middle low-carbon alloy steel, using higher Nb microalloying, first solidification when can sufficiently with
N, which is combined, is precipitated carbonitride, reduces B and forms BN in conjunction with N, to ensure the effect of the raising harden ability of B；Secondly, before forging rolling
When soaking and heat treatment, Nb (C, N) fining austenite grains are precipitated；Again, it is solid to reheat considerable part in austenite for heat treatment
Molten Nb-B easily in crystal boundary segregation, postpones austenite phase transformation, improves the harden ability of steel.Too low Nb or more comprehensive function is unknown
It is aobvious.Therefore, steel Nb content control of the present invention is in 0.08~0.12wt.%.
Add and add the strong nitride forming element such as Al, Ti or Nb in B steel alloy additionally to fix N, avoids the precipitation of BN, but
When Al content is excessively high, Al is formed in conjunction with O2O3Field trash, size is generally large and is difficult to control, and easily becomes fatigue crack
Source significantly reduces the fatigue behaviour of axle；TiN is higher due to Precipitation Temperature, it is easy to grow up to bigger size (micron order),
And there are sharp corners in form, it is very unfavorable to the toughness and fatigue behaviour of steel；Nb is usually precipitated in crystal boundary thin in steel alloy
Small carbonitride can improve the intensity and toughness of steel with pinning crystal boundary, fining austenite grains size.Therefore, pass through height
The combined microalloying of Nb, B collaboration, can be effectively improved its harden ability while guaranteeing axle steel obdurability.
Boron: segregation to crystal boundary improves grain-boundary strength, improves harden ability.It is acted on not more than when B content is lower than 0.0008wt.%
Obviously, effect increases unobvious when being higher than 0.0025wt.%.B content control in steel of the present invention 0.0008~
0.0025wt.%.
Vanadium: steel of the present invention is middle low-carbon alloy steel, using micro V microalloying, be precipitated in forging rolling (V, Mo) (C,
N), precipitation enhancement is generated, while the V being partially dissolved in austenite can improve harden ability.Steel V content control of the present invention exists
0.00~0.06wt.%, excessively high V content will lead to VC Precipitation Temperature is excessively high, amount of precipitation is excessive, particle size be easy it is coarse,
It is unfavorable for fining austenite grains, it is unfavorable to the intensity, toughness of axle steel etc..
Aluminium: Al is strong deoxidant element, and AlN can be also formed in conjunction with N, can play Grain refinement, and content is lower than
0.020wt.%, the above effect are unobvious.Al content in steel of the present invention is controlled in 0.020~0.040wt.%.
Nitrogen: in the presence of having Nb, V, Al etc. in steel, N can form carbonitride with them, can effectively inhibit austenite
Crystal grain is grown up.Nb, V, Al equal size design of steel of the present invention allow the control range of N content to be < 0.005wt.%.
Oxygen: O easily forms oxide and is mingled with, and is the impurity element of high speed axle steel, unfavorable to toughness, plasticity, serious to reduce
Fatigue behaviour.Steel control O content of the present invention is lower than 0.0015%.
Phosphorus: steel of the present invention is controlled P as impurity element, content < 0.010wt.%.
Sulphur: steel of the present invention is controlled S as impurity element, content < 0.010wt.%.
The present invention has the beneficial effect that:
The present invention provides a kind of the present application a kind of novel Cr-Ni-Mo-Nb-B-V high speed axles steel, uses
Low C, high Nb, B, Mo, micro- V combined microalloying, the design of higher Cr, Ni alloy in novel, it is preferred that emphasis is C, Nb, V, Mo, Cr member
The Proper Match of element: the content of V is controlled to generate precipitation enhancement, while improving harden ability；The Nb of high level can in steel
So that almost all of N is occupied by Nb (C, N), guarantee B still in solid solution state, significantly postponement austenite phase transformation, thus bright
The aobvious harden ability for improving steel；Moderate Cr is added, crystal grain and cementite are refined, significantly improves the harden ability of steel, improves material group
The uniformity knitted is improved the obdurability of material；Guarantee the harden ability of axle steel not because crystal grain is thin furthermore with the B of solid solution
Change and NbC is precipitated and reduces；Using higher Nb microalloying, improves the effect of harden ability, fining austenite grains and improve
The harden ability of steel；It cda alloy cost and its selects to close with synergistic effect of other alloying elements in terms of obdurability, harden ability
Suitable Ni content；The present invention gives full play to its effect in axle steel, and it is tiny and micro- based on martensite to obtain crystal grain
Tissue.
The present invention can obtain uniform fine grain austenite grain and the micro- conjunction of Nb using the heat treatment of quenching+high tempering twice
The martensitic structure of the second phase of gold nano enhancing realizes high-intensitive, high tenacity and high-hardenability excellent matching, finally makes high speed
Axle has the military services such as good shock resistance, antifatigue performance, excellent obdurability matching and good harden ability.
The average grain size of austenite grain is less than 12 μm in the tissue of axle steel of the present invention, yield strength Rp0.2
>=630MPa, tensile strength Rm >=800MPa, elongation percentage A >=20%, 5mm notch room temperature impact of collision absorb function KU2>=80J,
Ductile-brittle transition temperature is lower than -40 DEG C.
Other features and advantages of the present invention will illustrate in the following description, also, part can become from specification
It obtains it is clear that understand through the implementation of the invention.The objectives and other advantages of the invention can be by written explanation
Specifically noted method is achieved and obtained in book, claims and specific embodiment.
Specific embodiment
Below with reference to embodiment, the invention will be further described, and the embodiment of the present invention can be used for illustrating original of the invention
Reason.
The present invention relates to a kind of high toughness high hardenability high speed axle steel, the chemical component of the steel include C, Si, Cr,
Mn, V, Nb, B, Ni, Mo, Alt, P, S, O and N and Fe and inevitable impurity.
Preferably, C content is 0.24~0.32wt.%, and carbon is most important intensified element and the element for improving harden ability
One of, to guarantee that enough intensity and harden ability, C content must be in 0.24wt.% or more；But C content is higher than 0.32wt.%
When, the plasticity and toughness of steel can be significantly reduced.
Preferably, control Si content is reduced levels, is 0.20~0.40wt.%, silicon be solution strengthening effect it is significant but
Toughness also significant alloying element is damaged, while being also main deoxidant element in steel.The present invention mainly utilizes its deoxidation.
Preferably, Mn content is 0.60~0.90%, and manganese is the effective element of deoxidization desulfuration, while being also to guarantee harden ability
Element.But similar with Si, Mn content can significantly reduce the toughness of steel when being more than 0.90wt.%, Mn content is too low, cannot have
It imitates deoxidization desulfuration and guarantees the harden ability of steel.
Preferably, Cr content is 0.90~1.20wt.%, and adding moderate Cr in steel of the present invention can not only significantly improve
The harden ability of steel, moreover it is possible to improve the uniformity of material structure.(Fe, Cr) is formed when Cr is dissolved in cementite3When C alloy cementite,
It can play the role of refining crystal grain and cementite, to obtain uniformly tiny quenching crystal grain and tempered structure, make the strong of material
Toughness is improved.But excessive Cr and C Cr easy to form7C3Equal carbide, damage toughness, the plasticity of steel.
Preferably, the content of Ni is controlled in 0.50~1.50wt.%, its purpose is to improve steel toughness, and meanwhile it is comprehensive
Close cost of alloy and its cooperateing in terms of obdurability, harden ability with other alloying elements.
Preferably, the present invention controls 0.20~0.30wt.% of Mo content, and the present invention passes through Mo, Nb, V combined microalloying
Tiny austenite grain, significant nano-second-phase precipitation strengthening effect and high resistance to tempering are obtained, it is hereby achieved that
Fine grain, high tenacity high tempering tissue.In addition, the rational proportion of the alloying elements such as Mo and Cr, Ni and C, V, in tiny Austria
Good harden ability can be obtained under family name's body crystalline form.Mo content be lower than 0.20, above-mentioned effect is limited, too high levels, then on
It states effect saturation and even results in the effect surplus for improving resistance to tempering, the alloy and tempering heat treatment process cost of steel will be improved.
Preferably, the control of Nb content is middle low-carbon alloy steel in 0.08~0.12wt.%, steel of the present invention, and use is higher
Carbonitride can be precipitated in solidification first in Nb microalloying sufficiently in conjunction with N, reduce B and form BN in conjunction with N, to ensure B
Raising harden ability effect；Secondly, Nb (C, N) fining austenite grains are precipitated when soaking and heat treatment before forging rolling；Again
Secondary, heat treatment reheats the Nb-B of considerable part solid solution in austenite easily in crystal boundary segregation, postpones austenite phase transformation, improves steel
Harden ability, too low Nb or more comprehensive function are unobvious.The present invention passes through the combined microalloying of high Nb, B collaboration, can protect
Its harden ability is effectively improved while demonstrate,proving axle steel obdurability.
Preferably, for the B content control in steel of the present invention in 0.0008~0.0025wt.%, segregation to crystal boundary improves crystal boundary
Intensity improves harden ability.B content be lower than 0.0008wt.% when more than act on it is unobvious, and be higher than 0.0025wt.% when act on
Increase unobvious.
Preferably, in 0.00~0.06wt.%, steel of the present invention is middle low-carbon alloy steel for steel V content control of the present invention, is used
(V, Mo) (C, N) is precipitated in forging rolling in micro V microalloying, generates precipitation enhancement, while being partially dissolved in austenite
V can improve harden ability.Excessively high V content will lead to VC Precipitation Temperature is excessively high, amount of precipitation is excessive, particle size be easy it is thick
Greatly, it is unfavorable for fining austenite grains, it is unfavorable to the intensity, toughness of axle steel etc..
Preferably, it is strong deoxidant element that the Al content in steel of the present invention, which is controlled in 0.020~0.040wt.%, Al, may be used also
AlN is formed in conjunction with N, can play Grain refinement, and content is lower than 0.020wt.%, and the above effect is unobvious.
Preferably, in the presence of having Nb, V, Al etc. in steel, N can form carbonitride with them, can effectively inhibit difficult to understand
Family name's body crystal grain is grown up.Nb, V, Al equal size design of steel of the present invention allow the control range of N content to be < 0.005wt.%.
Preferably, impurity content is P in the present invention: < 0.010%, S: < 0.010%, O: < 0.0015%.
High tenacity high speed axles steel according to the present invention uses converter, electric furnace or vacuum induction furnace smelting, the outer essence of furnace
Continuous casting or molding after refining, for slab through the laggard driving axis forging rolling of cogging, heating temperature is 1150~1250 DEG C, difficult to understand when to avoid forging rolling
Family name's body is decomposed phase transformation, and finish-forging and finishing temperature are not less than 850 DEG C, air-cooled after forging rolling, using the heat of quenching+high tempering twice
Processing can obtain tiny austenite grain and excellent obdurability matching.Steel of the present invention by vacuum induction furnace smelting,
Middle 1#~5# is embodiment steel, and compared steel is the test steel designed according to EA4T standard.
Five specific embodiments are given below, wherein 1#~5# is embodiment steel, and compared steel is to design according to EA4T standard
Test steel, chemical component is as shown in table 1.Steel of the present invention by vacuum induction furnace smelting, embodiment steel and compared steel through smelt,
Casting, after forging rolling, be processed into normal room temperature tensile sample (L0=5d0, d0=5mm), Charpy notch impact specimen (10mm ×
10mm × 55mm), metallographic specimen (10mm × 10mm × 20mm), steel end-quenched (Φ 25mm × 110mm).Tensile sample, impact
Sample and metallographic specimen are heated to 920 DEG C in a vacuum furnace, keep the temperature 1h, then air-cooled, are then heated to 880 in a vacuum furnace again
DEG C, keep the temperature 1h, oil quenching.Tempering temperature when tempering is 675 DEG C, and soaking time 4h is air-cooled to room temperature after tempering.Stretch examination
Sample and impact specimen are processed into final size, and are accordingly tested according to national standard, and mechanical performance index is listed in table 2,
Metallographic specimen is ground again, polishes, and after being saturated picric acid aqueous corrosion, measures original austenite grain using division lines method
Degree, the results are shown in Table 2.Steel end-quenched, at standard sample, carries out end quenching examination by national standard through 920 DEG C of air-cooled post-processings of heat preservation 0.5h
Ending quenching hardness is tested and measures, the hardness number away from quenched end different distance is shown in Table 3.Tempered martensite is obtained after heat treatment, it is real
The favorable comprehensive mechanical property that 1#~5# steel obtains tensile strength 800MPa or more, room temperature impact function 80J or more is applied, and is obtained
To uniformly tiny austenite grain, average-size is 9-12 μm, and harden ability is significantly improved, and is had compared with compared steel more excellent
Obdurability matching.The chemical component of embodiment 1-5 is as shown in table 1, and mechanical performance index is listed in table 2, and metallographic specimen is again
Ground, polishing, and after being saturated picric acid aqueous corrosion, original austenite grain degree is measured using division lines method, as a result such as table 2
It is shown.Steel end-quenched, at standard sample, carries out end quenching test by national standard and measures end quenching through 920 DEG C of air-cooled post-processings of heat preservation 0.5h
Hardness, the hardness number away from quenched end different distance are shown in Table 3.In table 1-3, Rp0.2For yield strength, Rm is tensile strength, and A is to prolong
Stretch rate, KU2Function is absorbed for room temperature 5mm notch impact of collision.
1 chemical component of table (wt.%)
Mechanical property when table 2 is tempered
3 harden ability of table
Tempered martensite is obtained after heat treatment, embodiment 1#~5# steel obtains tensile strength 800MPa or more, room
The favorable comprehensive mechanical property of warm ballistic work 80J or more, and uniformly tiny austenite grain is obtained, average-size is 9-12 μ
M, harden ability are significantly improved, and match compared with compared steel with more excellent obdurability.
The purpose of the present invention is to provide a kind of boron containing niobium of fine grain, high tenacity and high-hardenability bullet train axle use
Steel.In chemical component, use in low C, the Alloying Design based on Cr, Ni, using high Nb, micro- V, Mo cooperate with it is polynary multiple
Closing microalloying thinking, it is preferred that emphasis is the Proper Match of C, Nb, V, Mo, Cr element gives full play to its effect in axle steel,
It obtains that crystal grain is tiny and microscopic structure based on martensite, guarantees the harden ability of axle steel not because of crystalline substance furthermore with the B of solid solution
Grain refinement and NbC are precipitated and reduce, and so that axle steel is had the comprehensive mechanical properties such as high intensity, high tenacity, high-hardenability, to have
For good shock resistance and antifatigue equal military services performance.
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 (4)
1. a kind of high toughness high hardenability high speed axle steel, which is characterized in that the yield strength R of the axle steelp0.2≥
630MPa, tensile strength Rm >=800MPa, elongation percentage A >=20%, 5mm notch room temperature impact of collision absorb function KU2>=80J, it is tough
Crisp transition temperature is lower than -40 DEG C；The chemical component of the steel includes B, wherein B be by weight percentage 0.0008~
0.0025%；
The chemical component of the steel is C:0.24~0.32% by weight percentage, Si:0.20~0.40%, Cr:0.90~
1.20%, Mn:0.60~0.90%, V:0.00~0.06%, Nb:0.08~0.12%, Ni:0.50~1.50%, Mo:0.20
~0.30%, Alt:0.020~0.040%, P: < 0.010%, S: < 0.010%, O: < 0.0015%, N: < 0.008%, remaining
For Fe and inevitable impurity；
The average grain size of austenite grain is less than 12 μm in the tissue of the axle steel.
2. a kind of preparation method using high toughness high hardenability high speed axle steel described in claim 1, which is characterized in that adopt
With converter, electric furnace or vacuum induction furnace smelting, continuous casting or molding after external refining, slab is through the laggard driving axis forging rolling of cogging, forging
It rolls rear air-cooled, is heat-treated, obtain high toughness high hardenability high speed axle steel；
After the heat treatment is specifically, the steel after forging rolling carries out quenching heat treatment twice in hardening media, then carry out at tempering
Reason, obtains the axle steel；
The temperature for carrying out first time quenching heat treatment is 900~950 DEG C, and the heating and thermal insulation time is 10~60min；
The temperature for carrying out second of quenching heat treatment is 850~900 DEG C, and the heating and thermal insulation time is 30~120min；
The temperature of tempering is 620~680 DEG C, soaking time 3~8 hours, air-cooled after tempering to arrive room temperature.
3. the preparation method of high toughness high hardenability high speed axle steel according to claim 2, which is characterized in that forging rolling
Heating temperature is 1150~1250 DEG C, and finish-forging and finishing temperature are not less than 850 DEG C.
4. the preparation method of high toughness high hardenability high speed axle steel according to claim 2, which is characterized in that described to quench
Fiery medium is water, water mist or oil.
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| CN109023102B (en) * | 2018-09-21 | 2020-09-15 | 首钢集团有限公司 | Microalloyed super-hardenability axle steel |
| CN109023107B (en) * | 2018-09-21 | 2020-04-21 | 首钢集团有限公司 | Super-hardenability axle steel |
| CN110079732B (en) * | 2019-05-15 | 2020-08-21 | 燕山大学 | Preparation method of super-hardenability steel |
| CN110592312B (en) * | 2019-10-23 | 2022-01-04 | 山西太钢不锈钢股份有限公司 | Preparation method of steel for high-speed axle |
| CN111705195B (en) * | 2020-06-08 | 2022-09-06 | 东莞材料基因高等理工研究院 | Precipitation strengthening heat treatment process for Nb-containing austenitic heat-resistant steel |
| CN113088825B (en) * | 2021-04-14 | 2023-02-28 | 江苏永钢集团有限公司 | Medium carbon microalloyed steel and method for eliminating mixed crystal structure thereof |
| CN114058964A (en) * | 2021-11-30 | 2022-02-18 | 宝武集团马钢轨交材料科技有限公司 | Steel for high-speed axle and heat treatment method and production method thereof |
| CN115558870B (en) * | 2022-11-04 | 2023-06-23 | 马鞍山钢铁股份有限公司 | Economical high-service-life high-power steel for wind power yaw bearing ring, bearing ring and production process |
| CN116024498A (en) * | 2022-12-26 | 2023-04-28 | 河南中原特钢装备制造有限公司 | Fine-grain high-strength-toughness mirror plastic die steel and heat treatment method thereof |
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