CN102719759B - Elastic bar steel for high-speed rail fastener and smelting production method thereof - Google Patents
Elastic bar steel for high-speed rail fastener and smelting production method thereof Download PDFInfo
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- CLZWAWBPWVRRGI-UHFFFAOYSA-N tert-butyl 2-[2-[2-[2-[bis[2-[(2-methylpropan-2-yl)oxy]-2-oxoethyl]amino]-5-bromophenoxy]ethoxy]-4-methyl-n-[2-[(2-methylpropan-2-yl)oxy]-2-oxoethyl]anilino]acetate Chemical compound CC1=CC=C(N(CC(=O)OC(C)(C)C)CC(=O)OC(C)(C)C)C(OCCOC=2C(=CC=C(Br)C=2)N(CC(=O)OC(C)(C)C)CC(=O)OC(C)(C)C)=C1 CLZWAWBPWVRRGI-UHFFFAOYSA-N 0.000 claims description 4
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- Treatment Of Steel In Its Molten State (AREA)
Abstract
The invention discloses an elastic bar steel for a high-speed rail fastener. The elastic bar steel comprises the chemical components (by mass percent) according to proportion: 0.40-0.52% of C, 1.8-2.1% of Si, 0.75-0.85% of Mn, 0.6-0.8% of Cr, 0.21-0.25% of V, 0.02-0.05% of Ti, 0.20-0.25% of Cu, 0.01-0.04% of rare earth REM, 0.0001-0.002% of Ca, 0.00005-0.0015% of Mg, 0.002-0.03% of Alt, less than or equal to 0.015% of P, less than or equal to 0.008% of S, less than or equal to 0.0012% of O, 0.002-0.007% of N, and the balance of Fe and other elements. The smelting production method comprises the processes of: primarily smelting, refining by using a steel ladle, carrying out vacuum treatment, and carrying out continuously casting/die casting and molding. According to the process, the quantity of impurities in the steel can be obviously reduced; the dimensions and the shapes of the impurities can be controlled, and the fatigue performance of the steel can be improved, and therefore, the smelting production method can be applied to the production of related spring steel varieties with high fatigue performance demands.
Description
Technical field
The present invention relates to a kind of for the steel for elastic bar of high-speed railway fastener and the smelting production method of this steel for elastic bar and the used for high-speed railway fastener made by this steel for elastic bar.
Background technology
Along with the development of China Express Railway, increasing for the demand of rail fastener system, specification of quality is also more and more higher, particularly strict especially up to the performance requriements of 350km/h ballast-free railway fastening system for speed per hour.Fastener is track important composition parts, and its Main Function is fixing rail tram, stops the vertical and horizontal displacement of rail, prevents that rail from tumbling.Spring is one of most important accessory in fastener system, and it is mainly that while utilizing recoverable deformation, stored energy plays mitigation vibrations and shock action mechanically.Due to it, in use bearing the repeated stresses such as long-term, periodically bending, torsion, therefore require spring to there is very high comprehensive mechanical performance.
At present, steel for elastic bar belongs to the high silicon series of high-carbon spring steel mostly, as 60Si
2mn, 60Si
2mnA, 60Si
2crA etc., this Series Steel surface decarburization tendency is serious and responsive, and this will directly affect the fatigue property of spring.Due to the self-defect of the steel grades such as 60Si2Mn, 60Si2MnA, substantially superseded in the production application of automobile hanging spring both at home and abroad, then adopt the domestic comparatively ripe new steel grades such as 55SiCr.Japan in 1984, when revision JIS spring steel standard, has increased the SUP12 that is equivalent to SAE9254.Si-Cr is steel SUP12(SAE9254) both absorbed the good elasticity attenuation resistance energy of Si-Mn steel, the high-hardenability of Cr-Mn steel, has overcome again the easy decarburizing tendency of Si-Mn steel, is a kind of extremely rising spring steel.China and Germany all remove a Si-Mn steel when revision spring steel standard, have increased a Si-Cr steel and have also objectively responded this trend.
China railways work business I, III and II type spring adopt respectively 60Si2Mn, the manufacture of 60Si2CrA spring steel.According to I (B) type, the stress distribution of III type spring largest unit, all exist the strength of materials to lay in problem on the low side.II type spring adopts the manufacture of 60Si2CrA spring steel, is prone to grain-boundary crack.Grain-boundary crack can directly produce tired source, thereby reduces work-ing life and the reliability of spring.There is equally margin of strength and elasticity attenuation resistance energy problem on the low side in Britain BS970 and German 38Si7 steel grade material.For example: the Britain e of PANDROL company type spring is after 5 years use, and existing 42% spring is lower than design requirements, there is in addition 42% elastic-strip pressure in criticality.Because the actual service stress of spring has met or exceeded the yield strength of material, its buckle press will continue decay, until with the yielding stress balance of material.Therefore illustrate that the fundamental strength of BS970-88 251A58 steel grade and elasticity attenuation resistance can still have much room for improvement.
Consider above-mentioned background, for meeting the needs of China Express Railway development, develop that a kind of anti-decarburization is strong, the high-speed railway steel for elastic bar of high strength, high tenacity, high corrosion resistance seems particularly urgent.
Summary of the invention
For the deficiencies in the prior art, one of object of the present invention is that low strength for current domestic steel for elastic bar, toughness are not enough, the easy problem of the aspect such as decarburization, researchs and develops a kind of novel high speed steel for elastic bar of railway; Two of object of the present invention is to provide a kind of production method with high fatigue property steel for elastic bar.
One of object of the present invention is achieved through the following technical solutions:
A kind of high-speed railway fastener system steel for elastic bar, by percentage to the quality, its chemical composition proportioning is: C 0.40～0.52%, Si 1.8～2.1%, Mn 0.75～0.85%, Cr 0.6～0.8%, V 0.21～0.25%, Ti 0.02～0.05%, Cu 0.20～0.25%, rare earth REM 0.01～0.045%, Ca 0.0001～0.002%, Mg 0.00005～0.0015%, (Alt represents Holo-Al content in steel to Alt, with the capable amount of oxygen in steel with and foreign material relevant, one of important indicator of composition of steel) 0.002～0.03%, P≤0.015%, S≤0.008%, O≤0.0012%, N 0.002～0.007%, all the other are Fe and other elements.
Described steel for elastic bar in 0.40～0.52% scope, is carried carbon content control high Si content by reduction C content and can be guaranteed that steel has certain intensity, the disadvantageous effect that can avoid to a certain extent again high carbon content to produce the toughness of steel, plasticity.The preferred carbon content scope 0.42～0.50% of the present invention.
Si content is controlled in 1.8～2.1% scopes.Higher Si content can make up the deficiency that reduces the strength decreased that C content brings, and Si can strengthen the elasticity attenuation resistance of spring steel simultaneously.When Si content is less than 1.0%, Si is dissolved in ferrite and does not reach the effect that increases the intensity of steel and strengthen spring steel elasticity attenuation resistance; When Si content surpasses 3.0%, further carry high Si content little to the elasticity attenuation resistance effect of increase steel, Si promotes graphite element simultaneously, can increase the decarburizing tendency of steel.
Mn content is controlled between 0.75～0.85%.Mn can improve the hardening capacity of steel, and the too low hardening capacity of content is inadequate, and too high levels can reduce the toughness of steel.Mn can also improve the intensity of steel, and research shows, Mn increases by 0.3% intensity improving and is equivalent to C and increases by 0.1% intensity improving.The preferred Mn content range 0.75～0.80% of the present invention.
P content≤0.015%.P can form microsegregation when solidification of molten steel, and when austenitizing heats, P is segregated on austenite grain boundary so that embrittlement of grain boundaries, thereby increases the fragility of steel, therefore P upper content limit is set as 0.015%.
S content≤0.008%.S also can be as P embrittlement austenite grain boundary, S can also form MnS and is mingled with simultaneously, affects the fatigue property of steel, therefore S content in steel is controlled at below 0.008%.
Cr content is 0.6～0.8%.Cr can improve the hardening capacity of steel, and Cr is carbide simultaneously, can prevent greying, alleviates the decarburizing tendency of steel.But too high Cr content will reduce the elasticity attenuation resistance of steel.
The content of V is controlled in 0.21～0.25% scope.V is carbide, and the carbide of V can suppress steel alligatoring of crystal grain during austenitizing in hot rolling and heat treatment process, plays the effect of crystal grain thinning.V can also play the effect of precipitation strength, and tiny carbide can improve dislocation motion resistance, thereby improves intensity, toughness and the elasticity attenuation resistance of steel.Low V content effect is not obvious, and too high V content can form the carbide of macrobead V, and these oarse-grained carbide can affect the fatigue property of steel as the non-metallic inclusion in steel.Within therefore the present invention is controlled at 0.21～0.25% scope by V content.
The Ti that adds content 0.02～0.05% catches hydrogen for fixed nitrogen.Ti can crystal grain thinning, improves the elasticity attenuation resistance of steel.The carbonitrides such as the TiC that Ti forms in steel and TiN are the highest hydrogen traps of trap energy in steel, can trap hydrogen to make it be evenly dispersed in intracrystalline, suppress the diffusion of hydrogen, improve the resistance for delayed fracture of steel.Ti content is unsuitable too high, otherwise can form oarse-grained nitride inclusion, affects the fatigue property of steel.
Ca is agent for purifying molten steel and inclusion modification agent.In spring steel, Ca is mainly used to inclusion to carry out denaturing treatment, thereby improves the fatigue property of steel.Within in steel, Ca content is controlled at 0.0001～0.002% scope.
In production process, inevitably contain Mg in molten steel, in order to guarantee steel inclusion composition, controlling its content is 0.00005～0.0015%.
N can with steel in alloying element form nitride or carbonitride, crystal grain thinning, improve the toughness of steel, in order to guarantee the formation of these compounds, in steel, needing has certain N content, but too high N content can reduce the mechanical property of steel and form oarse-grained nitride inclusion in steel, the fatigue lifetime of seriously reducing steel, therefore be controlled at N content in steel between 0.002～0.007%.
O content≤0.0012%.In steel, O exists mainly with inclusion form greatly, and research shows, in steel, be inversely proportional to the fatigue lifetime of O content and steel, so its upper limit is set as to 0.0012%.
Alt is the reductor of steel, and can be combined with nitrogen, eliminates the harm of nitrogen, and crystal grain thinning improves the toughness of steel, and Alt content span of control is 0.002～0.030%.
The content of Cu is 0.20～0.25%.Cu can increase the corrosion resistance of steel.
Rare earth REM content is 0.01～0.04%.Rare earth element can improve hardening capacity and the corrosion resistance of steel.In addition, rare earth in steel is enriched in grain boundaries by flooding mechanism conventionally, and this has just reduced impurity element (as P, S) and, in the segregation of crystal boundary, has strengthened crystal boundary, has improved the performance relevant to crystal boundary, as low temperature brittleness, toughness etc.Meanwhile, adding a certain amount of rare earth can be to the Al in steel
2o
3be mingled with and carry out sex change with MnS, improve fatigue lifetime and the transverse impact toughness of steel.For guaranteeing the effect of rare earth in steel, the preferred rare earth REM of the present invention content range 0.01～0.03%.When content of rare earth is too high, can make grain coarsening, and the rare earth of too high amount can form large inclusions, the fatigue lifetime of harm steel in steel.
Two of object of the present invention is to be achieved through the following technical solutions:
A kind of smelting production method of above-mentioned steel for elastic bar:
The one of the main reasons that steel for elastic bar is produced to harm fatigue lifetime is non-metallic inclusion residual in steel, and nonmetallic inclusionsin steel quantity and entire oxygen content in the steel content have substantial connection, when entire oxygen content in the steel content surpasses 10 * 10
-6time, linear between steel inclusion and total oxygen content, the amount of inclusions increases with the rising of total oxygen content.The control of oxygen content in steel is the key of metallurgical technology.Main points of the present invention are: just in furnace-ladle refining furnace-vacuum refining furnace (RH, VD)-continuous casting/mould note production process, strictly controlling the composition of steel, adopt slag absorption, molten steel optimization stirring, vacuum-treat, tundish flow control complex art to remove to greatest extent steel inclusion, and inclusion is carried out to denaturing treatment, reduce its harm to fatigue property, finally obtain superior in qualityly, be applicable to produce the strand of high fatigue life steel for elastic bar.
Its step comprises:
The first step, first furnace melting: first furnace adopts electric arc furnace or converter smelting;
(1) while adopting electric arc furnace smelting:
A) raw material adopts the mixture of steel scrap or steel scrap and molten iron, and wherein steel scrap ratio is not less than 50%, enters stove and controls the C>1.0% in raw material, P<0.05% before;
B) oxygen blast, oxygen purity >99.5%, the oxidation initial stage is controlled material temperature >=1550 ℃, and decarburized amount >=0.40% continuously, to guarantee that raw material removes in steel gas and be mingled with in liquid boiling state;
C) in oxidising process, form the foamy slag of good fluidity, basicity of slag is 2～3;
D) the oxidation later stage is controlled the quantity of slag in steel 2～3% by adjusting the add-on of slag making materials; Described slag making materials is CaO, CaF
2;
E) finish oxygen blast, according to basicity of slag R(CaO/SiO
2) add lime, thereby control phosphorus content in steel, be stabilized in below 0.01%, tapping, first furnace melting finishes;
(2) while adopting converter smelting:
A) control of converter terminal carbon adopts the high pattern of re-blowing of drawing, so-called high draw to re-blow refer to that terminal is by the slightly higher catch carbon that carries out of the desired carbon content of steel grade, the carbon content difference decision by analytical results and steel grade requirement after thermometric, sampling is re-blow the time.Adjust oxygen blast oxygen rifle height, add slag making materials in batches, and then control basicity of slag R(CaO/SiO
2)>=3.5, described slag making materials is CaO, CaF
2;
B) control the final slag basicity R(CaO/SiO after converter melting finishes
2)>=3.0, tapping, first furnace melting finishes;
During described just furnace tapping, the carbon content control in steel is 0.10～0.30%, and each component content of slag is controlled as CaO 35～55%, SiO
210～30%, Al
2o
31～8%, CaF
21～6%, FeO≤15%, MgO 4～9%, P≤0.01% in molten steel, is controlled by the slag thickness entering in Converter in ladle and is less than 50mm by the mode of pushing off the slag, and the mode adopting in the application is the mode of slag-blocking ball or slag stop cone or slide plate pushing off the slag; Control tapping temperature between 1630～1650 ℃, the Si-Fe alloy with Si content>=75% during tapping first carries out pre-deoxidation to molten steel, then adds Mn-Fe, V-Fe, Cr-Fe alloying;
Second step, ladle furnace refining: ladle enters LF station, more than power transmission heating 15min, adopt calcium carbide deoxidation, and progressively add lime, total quantity of slag (refer in ladle in the formed quantity of slag and ladle the ratio of Metal Weight) is about 15～18kg/t steel, and controlling refining slag component content is CaO 50～60%, SiO
25～12%, MgO 3～7%, Al
2o
312～18%, CaF
21～5%, T.Fe(refers to all iron content in slag, FeO and Fe in slag
2o
3adopt full iron processes to calculate and obtain) be less than 0.6%, refining duration 35～60min;
The 3rd step, vacuum-treat: with RH or VD, molten steel is carried out to vacuum-treat, control refining duration 25～40min, vacuum tightness are less than 1550 ℃ of 100Pa, temperature.The microgas scale of construction: RH is 10～25NL/min/t steel, VD is 1～5NL/min/t steel, vacuum-treat is finely tuned with RE alloyed molten steel component latter stage, vacuum-treat finishes rear molten steel to be carried out to calcium processing, guarantee soft blow time >=15min, argon flow amount 30～50L/min, when refining finishes, in steel, all compositions reach the scope of claim 1 defined.
The 4th step, continuous casting/mold casting forming: Metal in Tundish superheating temperature is controlled at 10～30 ℃, and continuous casting adopts totally-enclosed cast, pulling rate is 0.5～2.2m/min, and crystallizer and casting blank solidification end adopt induction stirring, and die casting adopts blowing argon cast.
The spring of being prepared by the above-mentioned mode of production is with just making high-speed railway fastener.
Beneficial effect of the present invention is mainly reflected in:
(1) by the ratio of the elements such as reasonably combined carbon, silicon, vanadium, manganese, guarantee that above-mentioned steel for elastic bar not only has certain intensity, also possess good anti-decarburization, toughness and erosion resistance.
(2) by adding appropriate rare earth REM, improve hardening capacity and the corrosion resistance of steel.In addition, rare earth can be to Al in steel
2o
3be mingled with and carry out denaturing treatment with MnS, thus fatigue lifetime and the transverse impact toughness of raising steel.
(3) steel of the present invention is without adding the expensive alloying elements such as Ni, Mo, with low cost.
(4) adopt the steel for elastic bar metallurgical quality of above production method to compare and have the following advantages with the steel for elastic bar of general production method: entire oxygen content in the steel content is low, is stabilized in 12 * 10
-6below; In steel substantially without fragility or indeformable inclusion; Steel inclusion size≤5 μ m, is well positioned to meet the processing requirement of preparing high-speed railway fastener.
Embodiment
According to above-mentioned designed chemical composition scope, in 10kg vacuum induction furnace, smelted 6 stove steel of the present invention; According to the composition of 55SiCr spring steel, 2 stove 55SiCr steel have been smelted as a comparison.Under vacuum, pour into steel ingot, be then forged into the bar that diameter is 16mm.Smithing technological parameter is: with stove, be heated to 1200 ℃, insulation 30min, then forges initial forging temperature >=1150 ℃, final forging temperature >=850 ℃.The 6 hotplate body embodiment that table 1 is steel of the present invention and the main chemical compositions of 2 stove comparative examples.
The main chemical compositions (mass percent) of table 1 steel of the present invention and compared steel
Note: chemical composition unlisted in table is: Ca 0.0003～0.002%, Mg 0.0003～0.0015%, Alt 0.002～0.03%, P≤0.015%, S ﹤ 0.008%.
On the bar that is 16mm at diameter, sample, according to this standard of GB/T 1222-2007(, to the standard of hardenability test, be: normalizing temperature 900-930 ℃, end quenching temperature 860 ± ℃,), spring steel 55SiCr and steel of the present invention are heat-treated, steel is heated to 860 ℃, insulation 32min, oil quenching, tempering 90min at 450 ℃ then, water-cooled.After thermal treatment, the metallographic structure of steel is tempering troostite.At room temperature measure its mechanical property with and decarburized layer deepness: tension test is according to standard GB/T228-2002 test, and test sample is of a size of L0=5d0, d0=10mm; Shock test adopts Charpy impact machine tester test according to standard GB/T229-1994, and test sample is of a size of 10 * 10 * 55mm, and groove is V-type mouth; Decarburized layer deepness adopts Metallography method determination according to standard GB/224-2008.6 specific embodiments that table 2 is steel of the present invention and the mechanical property of compared steel 55SiCr.Table 3 is the decarburized layer deepness of steel of the present invention and compared steel.
The mechanical property of table 2 steel of the present invention and compared steel
The decarburized layer deepness of table 3 steel of the present invention
In the present invention, novel steel for elastic bar metallurgy production method flow process is: hot metal pretreatment-converter-ladle furnace (LF)-vacuum oven (RH)-continuous casting, molten steel amount is 100 tons.
Raw material: steel scrap and molten iron, molten iron scrap ratio is 7:3; Control harmful element total amount and be less than 0.25%, feed stock for blast furnace keeps dry.
First furnace melting technology: adopt converter smelting, converter terminal is strictly controlled oxidation carbon content in latter stage, and C content is 0.15%, and converter finishing slag basicity of slag is that 3.2, FeO is not more than 10%, and in control molten steel, P content is below 0.012%; Tapping temperature is controlled at 1630～1650 ℃; The strict lower quantity of slag of tapping of controlling, ladle slag layer thickness is 50mm; In tapping process, in ladle, add Si-Fe alloy to carry out pre-deoxidation to molten steel.
Ladle furnace (LF stove) technique: adopt calcium carbide to carry out deoxidation, progressively add lime, total quantity of slag is 16kg/t steel, and refining slag composition (mass percent) is: CaO58.0%, SiO
210.0%, MgO7.0%, Al
2o
318.0%, CaF
25.0%, T.Fe is less than 0.6% (surplus is less than 2%, is analytical error and inevitable other impurity element); Reduce rapidly in slag MnO and below FeO content sum to 1%; The total refining time of LF is 55min; In steel, S content is controlled at below 0.0050%.
Vacuum oven (RH) technique: in RH deoxidation alloying process, control vacuum tightness is 50Pa; Tapping temperature is controlled at 1560 ℃ of left and right; RH argon blowing rate is 1200NL/min; Refining time 30min.Vacuum-treat is finely tuned with RE alloyed molten steel component latter stage, and vacuum-treat finishes to feed 200 meters, CaSi line in backward steel, guarantees soft blow time >=15min, and argon flow amount is controlled between 30～50L/min.
Argon is controlled principle: while carrying out steel inclusion denaturing treatment, adopt high argon gas stirring intensity; Make inclusion assemble and float while removing, adopt medium tenacity to stir; Latter stage is further removed residual fine foreign matter in steel in refining, adopts less air blowing intensity to carry out weak stirring.
Continuous casting process: tundish is used high-grade resistance to material; Metal in Tundish superheating temperature is 25 ℃; Crystallizer and casting blank solidification end adopt induction stirring, and continuous casting whole process is taked strict protection cast measure, and continuously cast bloom cross-sectional dimension is 160 * 160mm, and pulling rate is 2.0m/min.
Its concrete technological process comprises:
The first step, first furnace melting, except converter smelting, can also be to adopt electric arc furnace.
(1) while adopting electric arc furnace smelting:
A) raw material adopts the mixture of steel scrap or steel scrap and molten iron, and wherein steel scrap ratio is not less than 50%, enters stove and controls the C>1.0% in raw material, P<0.05% before;
B) oxygen blast, oxygen purity >99.5%, the oxidation initial stage is controlled material temperature >=1550 ℃, and decarburized amount >=0.40% continuously, to guarantee that raw material removes in steel gas and be mingled with in liquid boiling state;
C) in oxidising process, form the foamy slag of good fluidity, basicity of slag is 2～3;
D) the oxidation later stage is controlled the quantity of slag in steel 2～3% by adjusting the add-on of slag making materials; Described slag making materials is CaO, CaF
2;
E) finish oxygen blast, according to basicity of slag R(CaO/SiO
2) add lime, thereby control phosphorus content in steel, be stabilized in below 0.01%, tapping, first furnace melting finishes;
(2) while adopting converter smelting:
A) control of converter terminal carbon adopts the high pattern of re-blowing of drawing, so-called high draw to re-blow refer to that terminal is by the slightly higher catch carbon that carries out of the desired carbon content of steel grade, the carbon content difference decision by analytical results and steel grade requirement after thermometric, sampling is re-blow the time.Adjust oxygen blast oxygen rifle height, add slag making materials in batches, and then control basicity of slag R(CaO/SiO
2)>=3.5, described slag making materials is CaO, CaF
2;
B) control the final slag basicity R(CaO/SiO after converter melting finishes
2)>=3.0, tapping, first furnace melting finishes;
During described just furnace tapping, the carbon content control in steel is 0.10～0.30%, and each component content of slag is controlled as CaO 35～55%, SiO
210～30%, Al
2o
31～8%, CaF
21～6%, FeO≤15%, MgO 4～9%, P≤0.01% in molten steel, is controlled by the slag thickness entering in Converter in ladle and is less than 50mm by the mode of pushing off the slag, and the mode adopting in the application is the mode of slag-blocking ball or slag stop cone or slide plate pushing off the slag; Control tapping temperature between 1630～1650 ℃, the Si-Fe alloy with Si content>=75% during tapping first carries out pre-deoxidation to molten steel, then adds Mn-Fe, V-Fe, Cr-Fe alloying;
Second step, ladle furnace refining: ladle enters LF station, more than power transmission heating 15min, adopt calcium carbide deoxidation, and progressively add lime, total quantity of slag (refer in ladle in the formed quantity of slag and ladle the ratio of Metal Weight) is about 15～18kg/t steel, and controlling refining slag component content is CaO 50～60%, SiO
25～12%, MgO 3～7%, Al
2o
312～18%, CaF
21～5%, T.Fe(refers to all iron content in slag, FeO and Fe in slag
2o
3adopt full iron processes to calculate and obtain) be less than 0.6%, refining duration 35～60min;
The 3rd step, vacuum-treat: with RH or VD, molten steel is carried out to vacuum-treat, control refining duration 25～40min, vacuum tightness are less than 1550 ℃ of 100Pa, temperature.The microgas scale of construction: RH is 10～25NL/min/t steel, VD is 1～5NL/min/t steel, vacuum-treat is finely tuned with RE alloyed molten steel component latter stage, vacuum-treat finishes rear molten steel to be carried out to calcium processing, guarantee soft blow time >=15min, argon flow amount 30～50L/min, when refining finishes, in steel, all compositions reach the scope of claim 1 defined.
The 4th step, continuous casting/mold casting forming: Metal in Tundish superheating temperature is controlled at 10～30 ℃, and continuous casting adopts totally-enclosed cast, pulling rate is 0.5～2.2m/min, and crystallizer and casting blank solidification end adopt induction stirring, and die casting adopts blowing argon cast.
The present invention can also have other embodiment, and the technical scheme of the equal replacement of all employings or equivalent transformation form, within all dropping on the scope of requirement of the present invention.
Claims (5)
1. the smelting production method of steel for elastic bar for a high-speed railway fastener, it is characterized in that, described high-speed railway fastener steel for elastic bar, by percentage to the quality, its chemical composition proportioning is: C 0.40～0.52%, Si 1.8～2.1%, Mn 0.75～0.85%, Cr 0.6～0.8%, V 0.21～0.25%, Ti 0.02～0.05%, Cu 0.20～0.25%, rare earth REM 0.01～0.04%, Ca0.0001～0.002%, Mg 0.00005～0.0015%, Alt 0.002～0.03%, P≤0.015%, S≤0.008%, O≤0.0012%, N 0.002～0.007%, all the other are Fe and other elements, described smelting production method comprises the steps:
The first step, first furnace melting: first furnace adopts converter smelting;
A) control of converter terminal carbon adopts the high pattern of re-blowing of drawing, and adjusts oxygen blast oxygen rifle height, adds slag making materials in batches, and then controls basicity of slag R=CaO/SiO
2>=3.5, described slag making materials is CaO, CaF
2;
B) control the final slag basicity R=CaO/SiO after converter melting finishes
2>=3.0, tapping, first furnace melting finishes;
During described just furnace tapping, the carbon content control in steel is 0.10～0.30%, and each component content of slag is controlled as CaO 35～55%, SiO
210～30%, Al
2o
31～8%, CaF
21～6%, FeO≤15%, MgO 4～9%, P≤0.01% in molten steel, its each composition total amount is 100%; The mode of employing slag-blocking ball or slag stop cone or slide plate pushing off the slag is controlled by the slag thickness entering in Converter in ladle and is less than 50mm, control tapping temperature between 1630～1650 ℃, Si-Fe alloy with Si content>=75% during tapping first carries out pre-deoxidation to molten steel, then adds Mn-Fe, V-Fe, Cr-Fe alloying;
Second step, ladle furnace refining: ladle enters LF station, more than power transmission heating 15min, adopts calcium carbide deoxidation, also progressively adds lime, and total quantity of slag is 15～18kg/t steel, and controlling refining slag component content is CaO 50～60%, SiO
25～12%, MgO 3～7%, Al
2o
312～18%, CaF
21～5%, T.Fe is less than 0.6%, and its each composition total amount is 100%; Refining duration 35～60min;
The 3rd step, vacuum-treat: with RH or VD, molten steel is carried out to vacuum-treat, control refining duration 25～40min, vacuum tightness are less than 1550 ℃ of 100Pa, temperature; The microgas scale of construction: RH is 10～25NL/min/t steel, VD is 1～5NL/min/t steel, vacuum-treat is finely tuned with RE alloyed molten steel component latter stage, vacuum-treat finishes rear molten steel to be carried out to calcium processing, guarantee soft blow time >=15min, argon flow amount 30～50L/min, when refining finishes, in steel, all compositions reach the scope of defined;
The 4th step, continuous casting/mold casting forming: Metal in Tundish superheating temperature is controlled at 10～30 ℃, and continuous casting adopts totally-enclosed cast, pulling rate is 0.5～2.2m/min, and crystallizer and casting blank solidification end adopt induction stirring, and die casting adopts blowing argon cast.
2. according to claim 1, require the smelting production method of steel for elastic bar for described high-speed railway fastener, it is characterized in that: described C preferred content is 0.42～0.50%.
3. according to claim 1, require the smelting production method of steel for elastic bar for described high-speed railway fastener, it is characterized in that: described Mn preferred content is 0.75～0.80%.
4. according to claim 1, require the smelting production method of steel for elastic bar for described high-speed railway fastener, it is characterized in that: described rare earth REM preferred content is 0.01～0.03%.
5. a high-speed railway fastener, is characterized in that: the steel for elastic bar of being prepared by the smelting production method as described in as arbitrary in claim 1～4 is made.
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