CN104911497A - Method for producing high-strength carburized gear steel 19CrNi5 - Google Patents
Method for producing high-strength carburized gear steel 19CrNi5 Download PDFInfo
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Abstract
The invention belongs to the technical field of high-strength carburized gear steels, and in particular relates to a method for producing high-strength carburized gear steel 19CrNi5. The high-strength carburized gear steel is prepared by sequentially performing EBT electrosmelting, LF refining, VD furnace refining, continuous casting, thermal insulation, heating and 800 rod rolling based on a continuous rolling mill unit on raw materials. The high-strength carburized gear steel 19CrNi5 comprises the following components in percentage by weight: 0.170-0.185% of C, 0.22-0.30% of Si, 0.90-0.94% of Mn, no more than 0.030% of P, 0.020-0.035% of S, 0.95-0.99% of Cr, no more than 0.04% of Mo, 0.96-1.00% of Ni, no more than 0.10% of Cu, 0.020-0.035% of Alt and the balance of Fe and inevitable impurities. The method is capable of avoiding generation of a lot of cracks of continuously cast slabs, reducing the scrap rate and the polishing rate and improving the hardenability stability.
Description
Technical field
The present invention relates to high strength carbonized Gear Steel technical field, is particularly a kind of high strength carbonized Gear Steel 19CrNi5 production method.
Background technology
The original trade mark of 19CrNi5 converted steel is that " FIAT " company is low module, big speed ratio, high work load tractor gear need the 19CN5 steel developed, it is higher with hardening capacity, there is after carburizing and quenching hard and wear-resisting surface and tough and tensile heart portion, there is the advantages such as higher low-temperature impact toughness be widely applied in the world, thus become a typical trade mark of Cr-Ni system Pinion Steel, for making the component such as gear and gear shaft of automobile transmission case part and supporting high tenacity thereof, high strength, middle equal modulus.
19CrNi5 steel for main alloying elements with Cr, Ni, adds certain S content, has good forgeability, machinability, wear resistance and anti-fatigue performance, is the good material of propelling vehicle lightweight development.But because it easily cracks for during the straightening of peritectic steel continuously cast bloom, H requires that reference mark is many, it is large to control difficulty, it is large that obdurability requires that high and H controls difficulty of matching, purity of steel requires high, non-metallic inclusion is discharged not easily, oxygen level reduces the reasons such as difficulty is large, the rate of producing into the comparatively Series Gear steel such as CrMnTi is low, have impact on the production enthusiasm of iron and steel enterprise, also because its current actual mass stability still fully can not obtain guarantee, equally also have impact on the use enthusiasm of automobile gear industry.Current 19CrNi5 steel at home usage quantity is little, for meeting IVECO (IVECO) with domestic co-partnership company to the demand of 19CrNi5 converted steel material, is necessary to develop the batch stably manufactured that effective manufacturing technology ensures this steel grade.Promote the use of on this basis, promote the development of automotive light weight technology.
Summary of the invention
Technical problem to be solved by this invention is to provide a kind of high strength carbonized Gear Steel 19CrNi5 production method, to solve in 19CrNi5 steel making processes easily occur Cracks In Continuous Cast Billets, oxygen level is higher, hardening capacity fluctuation is large, hardening capacity mates not good quality problems with obdurability.
The present invention is achieved in that
A kind of high strength carbonized Gear Steel 19CrNi5 production method, raw material is successively by EBT electrosmelting, the refining of LF stove, the refining of VD stove, continuous casting, insulation, heating and 800 bar continuous rolling unit rollings, obtain steel, according to mass percentage content, comprise: C:0.170 ~ 0.185%, Si:0.22 ~ 0.30%, Mn:0.90 ~ 0.94%, P :≤0.030%, S:0.020 ~ 0.035%, Cr:0.95 ~ 0.99%, Mo :≤0.04%, Ni:0.96 ~ 1.00%, Cu :≤0.10, Alt:0.020 ~ 0.035%, surplus is Fe and inevitable impurity.
Further, molten iron is blended into after EBT electrosmelting power transmission 20min, molten iron temperature is: 1250 DEG C ~ 1350 DEG C, according to mass percent, iron water amount 70% ~ 85% joined by electric furnace, all the other are steel scrap, the carbon powder particle making foamed slag of granularity of jetting in slag when load melting more than 70% between 1 ~ 3mm, carbon dust winding-up amount is 6 ~ 7kg/t, require that foamy slag height reaches 500 ~ 800mm, oxidizing temperature 1580 DEG C ~ 1620 DEG C, after iron and steel stock is melting down, sampling analysis C, Mn, P, S and residual element, EBT electrosmelting requires tapping P≤0.023%, tapping temperature 1640 ~ 1660 DEG C.
Further, EBT electrosmelting tap 1/4 volume time, add carburelant 15 ~ 30kg, pre-deoxidant ferro-aluminum 150 ~ 200kg, quickened lime 500 ~ 600kg and iron alloy in molten steel per ton and carry out alloying.
Further, iron alloy comprises middle manganese add-on 300kg per ton, silicomanganese add-on 200kg, high chromium add-on 100kg, low chromium add-on 550kg, and molten steel per ton adds refining alumina balls 150 ~ 200kg.
Further, in the refining of LF stove, whole process carries out Bottom Argon Stirring, ladle controls 0.4 ~ 0.6MPa to argon gas during furnaceman LF position, heat up and argon gas control in refining period 0.4 ~ 0.6MPa, quiet Argon stage argon gas controls 0.1 ~ 0.3MPa, ladle enters LF station, adopt 20000 ~ 25000A big current intensificationization slag, when top of the slag fluctuation, when molten steel and electric arc are not exposed, add quickened lime, 200 ~ 300kg is added in per ton, after 5min first time sampling analysis chemical composition, alloy is added according to chemical composition target value, and carburetting, alloy and carbon dust should be added in argon gas stream, to promote alloy and carbon dust rapid melting and homogenizing.
Further, add diffusion deoxidizer 1 ~ 3kg/t when liquid steel temperature reaches 1600 ~ 1610 DEG C and carry out diffusive deoxidation, close fire door 10min, the second time sampling analysis chemical composition when liquid steel temperature reaches 1610 ~ 1620 DEG C of temperature, to confirm the deviation value that each chemical element component content requires apart from target value, after secondary sample is taken away, add diffusion deoxidizer and continue residue adjustment, add reductor total amount 1 ~ 2kg/t, slag basicity pH value is kept to be 2.5 ~ 3.5, viscosity coefficient of dross 0.80 ~ 1.20Pas, continue to keep melting under a white slag 20 ~ 30min simultaneously, when liquid steel temperature reaches 1670 ~ 1700 DEG C, during chemical composition ranges, carry out final deoxygenation and feed Al line 0.5 ~ 1.0kg/t, Ca-Si line 2.0 ~ 2.5kg/t is fed after feeding Al line 3min, line feeding terminates the quiet Argon of rear beginning, hold-time 10 ~ 20min.
Further, VD stove refining argon pressure before vacuum pump starts controls 0.1 ~ 0.3MPa, not exposed with top of the slag fine motion molten steel, timing is started when vacuum tightness reaches 100Pa, hold-time 10 ~ 15min, argon pressure is adjusted to 0.3 ~ 0.5MPa simultaneously, after quiet Argon terminates, in per ton, evenly adds carbonization rice husk heat preserving agent 40 ~ 80kg
Further, 3 machines 3 are adopted to flow curved type continuous caster continuous casting steel billet in continuous casting, continuous casting head stove bull ladle temperature 1592 ~ 1602 DEG C, 2nd stove bull ladle temperature 1575 ~ 1585 DEG C, the 3rd stove to tail stove bull ladle temperature 1565 ~ 1575 DEG C, total casting sequence 8 ~ 10 stove, pulling rate 0.80 ~ 0.85m/min, continuous casting head stove superheating temperature 30 ~ 35 DEG C, the 2nd stove to 20 ~ 30 DEG C, tail stove, crystallizer discharge 160M
3/ h, secondary cooling water specific water 0.30L/g, electricity stirs electric current 360A, straightening temperature 950 ~ 980 DEG C.
Further, in the heating phase, setting preheating section furnace temperature 500 ~ 750 DEG C, heat-up time 45 ~ 50min; Heating zone is divided into heating one section and two periods two stages, heats two sections of heat-up rates, 300 ~ 330 DEG C/h, heats one section of heat-up rate, 140 ~ 170 DEG C/h, heating secondary reformer temperature 1060 ~ 1080 DEG C, heat-up time 60 ~ 65min, heating primary reformer temperature 1220 ~ 1230 DEG C, heat-up time 55 ~ 60min; Soaking zone furnace temperature 1200 ~ 1220 DEG C, soaking time 60 ~ 90min, steel billet tapping temperature 1180 ~ 1200 DEG C, total heat-up time 220 ~ 265min.Be oxidizing atmosphere in heating period and soaking beforehand control stove, the soaking later stage is neutral or micro-reducing atmosphere.
Further, rolling sequence adopts reversing two high blooming mill roughing, start rolling temperature 1100 ~ 1150 DEG C, finishing temperature 900 ~ 950 DEG C, enters to cheat temperature 600 ~ 650 DEG C, soaking time 36 ~ 48h, play temperature≤150 DEG C, hole, cooling in heap temperature 300 ~ 500 DEG C, each stack weight 40 ~ 80 tons.
The present invention compared with prior art, beneficial effect is: the application of manufacturing technology of the present invention, avoid a large amount of generations of Cracks In Continuous Cast Billets, reduce scrap rate and reconditioning rate, improve the stability of hardening capacity, optimize the matched well relation of H and Fracture of Material, reduce oxygen level, improve purity of steel, reduce the scrap rate that gear blank is produced, the product that improve Gear Processing manufacturing becomes rate, extend the safe operating life of gear, mean the resource correspondingly reducing and produce Gear Processing manufacture from steel, energy consumption, be conducive to " resource-conserving, environmentally friendly " society development.
Embodiment
In order to make object of the present invention, technical scheme and advantage clearly understand, below in conjunction with embodiment, the present invention is further elaborated.Should be appreciated that specific embodiment described herein only in order to explain the present invention, be not intended to limit the present invention.
Embodiment 1
A kind of high strength carbonized Gear Steel 19CrNi5 production method, raw material by EBT electrosmelting, the refining of LF stove, the refining of VD stove, continuous casting, insulation, heating and 800 bar continuous rolling unit rollings, obtains steel successively, according to mass percentage content, comprising: C:0.180%, Si:0.25%, Mn:0.92%, P :≤0.030%, S:0.025%, Cr:0.97%, Mo :≤0.04%, Ni:0.98%, Cu :≤0.10, Alt:0.030%, surplus is Fe and inevitable impurity.
The smelting stage
Be blended into molten iron, molten iron temperature 1250 DEG C after electric furnace charging power transmission 20min, according to mass percent, iron water amount 80% joined by electric furnace, and all the other are selected steel scrap.Iron alloy and various reductor, covering slag, slag making materials keep dry.Electrosmelting adopts dioxygen oxidation method, ensure rapid melting furnace charge, decarburization fast, the carbon powder particle making foamed slag of granularity of jetting in slag when load melting more than 70% between 1 ~ 3mm, carbon dust winding-up amount is 7kg/t, require that foamy slag height reaches 800mm, oxidizing temperature 1580 DEG C.After iron and steel stock is melting down, sampling analysis C, Mn, P, S and residual element.Oxidation forms high alkalinity, the large quantity of slag, low temperature slag to strengthen dephosphorization effect early stage, and electric furnace requires tapping P≤0.023%, tapping temperature 1640 DEG C.Add carburelant 15kg, pre-deoxidant ferro-aluminum 150kg, quickened lime 500kg (in molten steel per ton) and various iron alloy during electric furnace steel tapping 1/4 and carry out alloying.Manganese add-on 300kg, silicomanganese add-on 200kg, high chromium add-on 100kg, low chromium add-on 550kg in iron alloy, and add refining alumina balls 150 ~ 200kg (in molten steel per ton).
After electrosmelting, molten steel proceeds to the refining of LF stove, and in LF refining process, whole process carries out Bottom Argon Stirring, and ladle, to argon gas control 0.4MPa during furnaceman LF position, heats up and argon gas control in refining period 0.4MPa, quiet Argon stage argon gas control 0.1MPa.Ladle enters LF station, adopts 20000 ~ 25000A big current intensificationizations slag, when the top of the slag fluctuate, molten steel and electric arc not exposed time, add quickened lime 200kg (in molten steel per ton), sampling analysis chemical composition for the first time after 5min, i.e. a total analysis.After one time total analysis chemical composition result is quoted, add alloy according to chemical composition target value, and carburetting, alloy and carbon dust should be added in argon gas stream, to promote alloy and carbon dust rapid melting and homogenizing.
Add diffusion deoxidizer (carbon dust and ferrosilicon powder) 1kg/t when liquid steel temperature reaches 1600 DEG C and carry out diffusive deoxidation, close fire door 10min.Form white slag after 5min, the second time sampling analysis chemical composition when liquid steel temperature reaches 1610 ~ 1620 DEG C of temperature, i.e. the full composition of secondary, to confirm the deviation value that each chemical element component content requires apart from target value.After secondary sample is taken away, add diffusion deoxidizer and continue residue adjustment, add reductor total amount 1kg/t, keep slag basicity pH2.5, viscosity coefficient of dross 0.80Pas, to obtain that there is good fluidity, absorption be mingled with, deoxidation, desulfurization and insulation effect ability strong, continue to keep melting under a white slag 20min, to realize the refining of whole process white slag simultaneously.After secondary total analysis chemical composition result is quoted, continue to carry out chemical composition fine setting according to chemical composition target value in table 5.When liquid steel temperature reaches 1670 DEG C, when chemical composition meets table 5 internal control scope, carry out final deoxygenation and feed Al line 0.5kg/t, after feeding Al line 3min, feed Ca-Si line 2.0kg/t.Line feeding terminates the quiet Argon of rear beginning, hold-time 10min.
VD stove is argon pressure control 0.1MPa before vacuum pump starts, and is advisable so that top of the slag fine motion molten steel is not exposed.Start timing when vacuum tightness reaches 100Pa, hold-time 10min, is adjusted to 0.3 ~ 0.5MPa by argon pressure simultaneously.After quiet Argon terminates, evenly add carbonization rice husk heat preserving agent 40 ~ 80kg (in molten steel per ton), still should have during fluctuation in every stove quiet Argon molten steel in latter stage face and add, and ensure its uniform fold.
The narrow chemical Composition Control of smelting operation implementation Process, namely C content control objectives fluctuation range be no more than ± 0.0075%, Mn, Cr content target fluctuation range is no more than ± and 0.02%, Ni content target fluctuation range is no more than ± and 0.01%, Alt content target fluctuation range is no more than ± and 0.0075%, residual element Mo≤0.04%, Cu≤0.10%, the restriction in addition necessary to it, to avoid bringing adverse influence to the fluctuation of steel H, namely each chemical element fluctuation range centered by target value does not exceed internal control scope.
The continuous casting stage
3 machines 3 are adopted to flow curved type continuous caster continuous casting steel billet, strand sectional dimension 235mm × 265mm.Continuous casting head stove bull ladle temperature 1592 DEG C, the 2nd stove bull ladle temperature 1575 DEG C, the 3rd stove to tail stove bull ladle temperature 1565 ~ DEG C, total casting sequence 8 stove.Pulling rate 0.80m/min.Continuous casting head stove superheating temperature 30 DEG C, the 2nd stove is to 20 DEG C, tail stove.Crystallizer discharge 160M
3/ h, secondary cooling water specific water 0.30L/g, electricity stirs electric current 360A, straightening temperature 950 ~ 980 DEG C, with the tendency suppressing peritectic steel easily to produce slab surface crack, adopts low carbon protective slag protective casting.
Heating phase
Hot charging and hot rolling of continuous casting slab, when not ensureing hot charging temperature, strand is incubated.The accumulation of heat walking beam heating furnace heating that employing is fuel with blast furnace, coke oven mixed gas, reasonable set and the temperature and time distributing preheating, heating, insulation three phases, the continous-stable of the homogeneity and rate of heating of strengthening Heating temperature controls, ensure strand homogeneous temperature, reduce male and female face and head and tail temperature difference, prevent austenite crystal thick, and proper extension high temperature section soaking time, promote the homogenizing of carbon and alloying element.Setting preheating section furnace temperature 500 ~ 750 DEG C, heat-up time 45min; Heating zone is divided into heating one section and two periods two stages according to the requirement difference of slab heating-up speed, heats two sections of heat-up rates, 300 DEG C/h, heats one section of heat-up rate, 140 DEG C/h, heating secondary reformer temperature 1060 DEG C, heat-up time 60min, heating primary reformer temperature 1220 DEG C, heat-up time 55min; Soaking zone furnace temperature 1200 DEG C, soaking time 60min.Steel billet tapping temperature 1180 DEG C, total heat-up time 220min.Be oxidizing atmosphere in heating period and soaking beforehand control stove, the soaking later stage is neutral or micro-reducing atmosphere.
Rolling sequence
Adopt reversing two high blooming mill roughing preparation side, without memorial archway short-stress path 800 Continuous mill train rolling Φ 40 ~ 150mm size round steel.Start rolling temperature 1100 DEG C, finishing temperature 900 DEG C, the above specification steel insulation of Φ 85mm, enters to cheat temperature 600 DEG C, soaking time 36h, plays temperature≤150 DEG C, hole, Φ 40 ~ 80mm specification steel cooling in heap, cooling in heap temperature 300 DEG C, each stack weight 40 tons.
Embodiment 2
Raw material by EBT electrosmelting, the refining of LF stove, the refining of VD stove, continuous casting, insulation, heating and 800 bar continuous rolling unit rollings, obtains steel, according to mass percentage content successively, comprise: C:0.170%, Si:0.22 ~ 0.30%, Mn:0.90%, P :≤0.030%, S:0.020%, Cr:0.95%, Mo :≤0.04%, Ni:0.96%, Cu :≤0.10, Alt:0.020%, surplus is that Fe and inevitable impurity smelt the stage
Be blended into molten iron, molten iron temperature 1350 DEG C after electric furnace charging power transmission 20min, electric furnace is joined iron water amount and is not less than 85%, and all the other are selected steel scrap.Iron alloy and various reductor, covering slag, slag making materials keep dry.Electrosmelting adopts dioxygen oxidation method, ensure rapid melting furnace charge, decarburization fast, the carbon powder particle making foamed slag of granularity of jetting in slag when load melting more than 70% between 3mm, carbon dust winding-up amount is 6 ~ 7kg/t, require that foamy slag height reaches 800mm, oxidizing temperature 1620 DEG C.After iron and steel stock is melting down, sampling analysis C, Mn, P, S and residual element.Oxidation forms high alkalinity, the large quantity of slag, low temperature slag to strengthen dephosphorization effect early stage, and electric furnace requires tapping P≤0.023%, tapping temperature 1660 DEG C.Add carburelant 30kg, pre-deoxidant ferro-aluminum 200kg, quickened lime 600kg (per ton) and various iron alloy during electric furnace steel tapping 1/4 and carry out alloying.Manganese add-on 300kg, silicomanganese add-on 200kg, high chromium add-on 100kg, low chromium add-on 550kg (per ton) in iron alloy, and add refining alumina balls 200kg (per ton).
After electrosmelting, molten steel proceeds to the refining of LF stove, and in LF refining process, whole process carries out Bottom Argon Stirring, and ladle, to argon gas control 0.6MPa during furnaceman LF position, heats up and argon gas control in refining period 0.6MPa, quiet Argon stage argon gas control 0.3MPa.Ladle enters LF station, adopts 20000 ~ 25000A big current intensificationizations slag, when the top of the slag fluctuate, molten steel and electric arc not exposed time, add quickened lime 300kg (per ton), sampling analysis chemical composition for the first time after 5min, i.e. a total analysis.After one time total analysis chemical composition result is quoted, add alloy according to chemical composition target value, and carburetting, alloy and carbon dust should be added in argon gas stream, to promote alloy and carbon dust rapid melting and homogenizing.
Add diffusion deoxidizer (carbon dust and ferrosilicon powder) 3kg/t when liquid steel temperature reaches 1610 DEG C and carry out diffusive deoxidation, close fire door 10min.Form white slag after 5min, the second time sampling analysis chemical composition when liquid steel temperature reaches 1620 DEG C of temperature, i.e. the full composition of secondary, to confirm the deviation value that each chemical element component content requires apart from target value.After secondary sample is taken away, add diffusion deoxidizer and continue residue adjustment, add reductor total amount 2kg/t, keep slag basicity 3.5, viscosity coefficient of dross 1.20Pas, to obtain that there is good fluidity, absorption be mingled with, deoxidation, desulfurization and insulation effect ability strong, continue to keep melting under a white slag 30min, to realize the refining of whole process white slag simultaneously.After secondary total analysis chemical composition result is quoted, continue to carry out chemical composition fine setting according to chemical composition target value in table 5.When liquid steel temperature reaches 1700 DEG C, when chemical composition meets internal control scope, carry out final deoxygenation and feed Al line 1.0kg/t, after feeding Al line 3min, feed Ca-Si line 2.5kg/t.Line feeding terminates the quiet Argon of rear beginning, hold-time 20min.
VD stove is argon pressure control 0.3MPa before vacuum pump starts, and is advisable so that top of the slag fine motion molten steel is not exposed.Start timing when vacuum tightness reaches 100Pa, hold-time 15min, is adjusted to 0.5MPa by argon pressure simultaneously.After quiet Argon terminates, evenly add carbonization rice husk heat preserving agent 40 ~ 80kg, still should have during fluctuation in every stove quiet Argon molten steel in latter stage face and add, and ensure its uniform fold.
The narrow chemical Composition Control of smelting operation implementation Process, namely C content control objectives fluctuation range be no more than ± 0.0075%, Mn, Cr content target fluctuation range is no more than ± and 0.02%, Ni content target fluctuation range is no more than ± and 0.01%, Alt content target fluctuation range is no more than ± and 0.0075%, residual element Mo≤0.04%, Cu≤0.10%, the restriction in addition necessary to it, with avoid to steel H fluctuation bring adverse influence, namely each chemical element in table 5 centered by target value fluctuation range do not exceed internal control scope.
The continuous casting stage
3 machines 3 are adopted to flow curved type continuous caster continuous casting steel billet, strand sectional dimension 235mm × 265mm.Continuous casting head stove bull ladle temperature 1602 DEG C, the 2nd stove bull ladle temperature 1585 DEG C, the 3rd stove to tail stove bull ladle temperature 1575 DEG C, total casting sequence 10 stove.Pulling rate 0.85m/min.Continuous casting head stove superheating temperature 35 DEG C, the 2nd stove is to 30 DEG C, tail stove.Crystallizer discharge 160M
3/ h, secondary cooling water specific water 0.30L/g, electricity stirs electric current 360A, straightening temperature 980 DEG C, with the tendency suppressing peritectic steel easily to produce slab surface crack, adopts low carbon protective slag protective casting.
Heating phase
Hot charging and hot rolling of continuous casting slab, when not ensureing hot charging temperature, strand is incubated.The accumulation of heat walking beam heating furnace heating that employing is fuel with blast furnace, coke oven mixed gas, reasonable set and the temperature and time distributing preheating, heating, insulation three phases, the continous-stable of the homogeneity and rate of heating of strengthening Heating temperature controls, ensure strand homogeneous temperature, reduce male and female face and head and tail temperature difference, prevent austenite crystal thick, and proper extension high temperature section soaking time, promote the homogenizing of carbon and alloying element.Setting preheating section furnace temperature 750 DEG C, heat-up time 50min; Heating zone is divided into heating one section and two periods two stages according to the requirement difference of slab heating-up speed, heats two sections of heat-up rates, 330 DEG C/h, heats one section of heat-up rate, 170 DEG C/h, heating secondary reformer temperature 1080 DEG C, heat-up time 65min, heating primary reformer temperature 1230 DEG C, heat-up time 60min; Soaking zone furnace temperature 1220 DEG C, soaking time 90min.Steel billet tapping temperature 1200 DEG C, total heat-up time 265min.Be oxidizing atmosphere in heating period and soaking beforehand control stove, the soaking later stage is neutral or micro-reducing atmosphere.
Rolling sequence
Adopt reversing two high blooming mill roughing preparation side, without memorial archway short-stress path 800 Continuous mill train rolling Φ 150mm size round steel.Start rolling temperature 1150 DEG C, finishing temperature 950 DEG C, the above specification steel insulation of Φ 85mm, enters to cheat temperature 650 DEG C, soaking time 48h, plays temperature≤150 DEG C, hole, Φ 40 ~ 80mm specification steel cooling in heap, cooling in heap temperature 500 DEG C, each stack weight 80 tons.
Embodiment 3
A kind of high strength carbonized Gear Steel 19CrNi5 production method, raw material by EBT electrosmelting, the refining of LF stove, the refining of VD stove, continuous casting, insulation, heating and 800 bar continuous rolling unit rollings, obtains steel successively, according to mass percentage content, comprising: C:0.180%, Si:0.28%, Mn:0.91%, P :≤0.030%, S:0.030%, Cr:0.97%, Mo :≤0.04%, Ni:0.98%, Cu :≤0.10, Alt:0.030%, surplus is Fe and inevitable impurity.
The smelting stage
Be blended into molten iron, molten iron temperature 1300 DEG C after electric furnace charging power transmission 20min, electric furnace is joined iron water amount and is not less than 80%, and all the other are selected steel scrap.Iron alloy and various reductor, covering slag, slag making materials keep dry.Electrosmelting adopts dioxygen oxidation method, ensure rapid melting furnace charge, decarburization fast, the carbon powder particle making foamed slag of granularity of jetting in slag when load melting more than 70% between 2mm, carbon dust winding-up amount is 6.5kg/t, require that foamy slag height reaches 600mm, oxidizing temperature 1600 DEG C.After iron and steel stock is melting down, sampling analysis C, Mn, P, S and residual element.Oxidation forms high alkalinity, the large quantity of slag, low temperature slag to strengthen dephosphorization effect early stage, and electric furnace requires tapping P≤0.023%, tapping temperature 1650 DEG C.In per ton, add carburelant 20kg, pre-deoxidant ferro-aluminum 180kg, quickened lime 550kg and various iron alloy during electric furnace steel tapping 1/4 and carry out alloying.Manganese add-on 300kg, silicomanganese add-on 200kg, high chromium add-on 100kg, low chromium add-on 550kg (per ton) in iron alloy, and add refining alumina balls 150 ~ 200kg (per ton).
After electrosmelting, molten steel proceeds to the refining of LF stove, and in LF refining process, whole process carries out Bottom Argon Stirring, and ladle, to argon gas control 0.5MPa during furnaceman LF position, heats up and argon gas control in refining period 0.5MPa, quiet Argon stage argon gas control 0.2MPa.Ladle enters LF station, adopts 20000 ~ 25000A big current intensificationizations slag, when the top of the slag fluctuate, molten steel and electric arc not exposed time, add quickened lime 250kg (per ton), sampling analysis chemical composition for the first time after 5min, i.e. a total analysis.After one time total analysis chemical composition result is quoted, add alloy according to chemical composition target value, and carburetting, alloy and carbon dust should be added in argon gas stream, to promote alloy and carbon dust rapid melting and homogenizing.
Add diffusion deoxidizer (carbon dust and ferrosilicon powder) 2kg/t when liquid steel temperature reaches 1600 ~ 1610 DEG C and carry out diffusive deoxidation, close fire door 10min.Form white slag after 5min, the second time sampling analysis chemical composition when liquid steel temperature reaches 1610 ~ 1620 DEG C of temperature, i.e. the full composition of secondary, to confirm the deviation value that each chemical element component content requires apart from target value.After secondary sample is taken away, add diffusion deoxidizer and continue residue adjustment, add reductor total amount 1.5kg/t, keep slag basicity Ph3, viscosity coefficient of dross 0.90Pas, to obtain that there is good fluidity, absorption be mingled with, deoxidation, desulfurization and insulation effect ability strong, continue to keep melting under a white slag 25min, to realize the refining of whole process white slag simultaneously.After secondary total analysis chemical composition result is quoted, continue to carry out chemical composition fine setting according to chemical composition target value.When liquid steel temperature reaches 1670 ~ 1700 DEG C, when chemical composition meets internal control scope, carry out final deoxygenation and feed Al line 0.8kg/t, after feeding Al line 3min, feed Ca-Si line 2.3kg/t.Line feeding terminates the quiet Argon of rear beginning, hold-time 15min.
VD stove is argon pressure control 0.2MPa before vacuum pump starts, and is advisable so that top of the slag fine motion molten steel is not exposed.Start timing when vacuum tightness reaches 100Pa, hold-time 12min, is adjusted to 0.4MPa by argon pressure simultaneously.After quiet Argon terminates, evenly add carbonization rice husk heat preserving agent 60kg (molten steel per ton), still should have during fluctuation in every stove quiet Argon molten steel in latter stage face and add, and ensure its uniform fold.
The narrow chemical Composition Control of smelting operation implementation Process, namely C content control objectives fluctuation range be no more than ± 0.0075%, Mn, Cr content target fluctuation range is no more than ± and 0.02%, Ni content target fluctuation range is no more than ± and 0.01%, Alt content target fluctuation range is no more than ± and 0.0075%, residual element Mo≤0.04%, Cu≤0.10%, the restriction in addition necessary to it, to avoid bringing adverse influence to the fluctuation of steel H, namely each chemical element fluctuation range centered by target value does not exceed internal control scope.
The continuous casting stage
3 machines 3 are adopted to flow curved type continuous caster continuous casting steel billet, strand sectional dimension 235mm × 265mm.Continuous casting head stove bull ladle temperature 1592 DEG C, the 2nd stove bull ladle temperature 1575 DEG C, the 3rd stove to tail stove bull ladle temperature 1575 DEG C, total casting sequence 8 stove.Pulling rate 0.85m/min.Continuous casting head stove superheating temperature 35 DEG C, the 2nd stove is to 25 DEG C, tail stove.Crystallizer discharge 160M
3/ h, secondary cooling water specific water 0.30L/g, electricity stirs electric current 360A, straightening temperature 950 ~ 980 DEG C, with the tendency suppressing peritectic steel easily to produce slab surface crack, adopts low carbon protective slag protective casting.
Heating phase
Hot charging and hot rolling of continuous casting slab, when not ensureing hot charging temperature, strand is incubated.The accumulation of heat walking beam heating furnace heating that employing is fuel with blast furnace, coke oven mixed gas, reasonable set and the temperature and time distributing preheating, heating, insulation three phases, the continous-stable of the homogeneity and rate of heating of strengthening Heating temperature controls, ensure strand homogeneous temperature, reduce male and female face and head and tail temperature difference, prevent austenite crystal thick, and proper extension high temperature section soaking time, promote the homogenizing of carbon and alloying element.Setting preheating section furnace temperature 600 DEG C, heat-up time 45min; Heating zone is divided into heating one section and two periods two stages according to the requirement difference of slab heating-up speed, heats two sections of heat-up rates, 320 DEG C/h, heats one section of heat-up rate, 155 DEG C/h, heating secondary reformer temperature 1070 DEG C, heat-up time 62min, heating primary reformer temperature 1220 DEG C, heat-up time 60min; Soaking zone furnace temperature 1220 DEG C, soaking time 80min.Steel billet tapping temperature 1180 DEG C, total heat-up time 220 ~ 265min.Be oxidizing atmosphere in heating period and soaking beforehand control stove, the soaking later stage is neutral or micro-reducing atmosphere.
Rolling sequence
Adopt reversing two high blooming mill roughing preparation side, without memorial archway short-stress path 800 Continuous mill train rolling Φ 40 ~ 150mm size round steel.Start rolling temperature 1120 DEG C, finishing temperature 930 DEG C, the above specification steel insulation of Φ 85mm, enters to cheat temperature 620 DEG C, soaking time 40h, plays temperature≤150 DEG C, hole, Φ 40 ~ 80mm specification steel cooling in heap, cooling in heap temperature 400 DEG C, each stack weight 60 tons.
Test example
The steel prepared in embodiment are detected,
1 H
Sample adopts 980 ± DEG C normalizing, 980 ± 5 DEG C of quench treatment, and H requires as shown in table 1.
The H of table 219CrNi5 steel
2 mechanical properties
Mechanical property requirements is as shown in table 2.Mechanical property blank specimen size Φ 15mm, sample blank heat treating regime: 875 ± 10 DEG C of quenchings, oil cooling, 170 ± 10 DEG C of tempering, air cooling.
The mechanical property requirements of table 219CrNi5 steel
The foregoing is only preferred embodiment of the present invention, not in order to limit the present invention, all any amendments done within the spirit and principles in the present invention, equivalent replacement and improvement etc., all should be included within protection scope of the present invention.
Claims (10)
1. a high strength carbonized Gear Steel 19CrNi5 production method, it is characterized in that, raw material is successively by EBT electrosmelting, the refining of LF stove, the refining of VD stove, continuous casting, insulation, heating and 800 bar continuous rolling unit rollings, obtain steel, according to mass percentage content, comprise: C:0.170 ~ 0.185%, Si:0.22 ~ 0.30%, Mn:0.90 ~ 0.94%, P :≤0.030%, S:0.020 ~ 0.035%, Cr:0.95 ~ 0.99%, Mo :≤0.04%, Ni:0.96 ~ 1.00%, Cu :≤0.10, Alt:0.020 ~ 0.035%, surplus is Fe and inevitable impurity.
2. according to high strength carbonized Gear Steel 19CrNi5 production method according to claim 1, it is characterized in that, molten iron is blended into after EBT electrosmelting power transmission 20min, molten iron temperature is: 1250 DEG C ~ 1350 DEG C, according to mass percent, iron water amount 70% ~ 85% joined by electric furnace, all the other are steel scrap, the carbon powder particle making foamed slag of granularity of jetting in slag when load melting more than 70% between 1 ~ 3mm, carbon dust winding-up amount is 6 ~ 7kg/t, require that foamy slag height reaches 500 ~ 800mm, oxidizing temperature 1580 DEG C ~ 1620 DEG C, after iron and steel stock is melting down, sampling analysis C, Mn, P, S and residual element, EBT electrosmelting requires tapping P≤0.023%, tapping temperature 1640 ~ 1660 DEG C.
3. according to high strength carbonized Gear Steel 19CrNi5 production method according to claim 2, it is characterized in that, EBT electrosmelting tap 1/4 volume time, add carburelant 15 ~ 30kg, pre-deoxidant ferro-aluminum 150 ~ 200kg, quickened lime 500 ~ 600kg and iron alloy in molten steel per ton and carry out alloying.
4. according to high strength carbonized Gear Steel 19CrNi5 production method according to claim 3, it is characterized in that, iron alloy comprises middle manganese add-on 300kg per ton, silicomanganese add-on 200kg, high chromium add-on 100kg, low chromium add-on 550kg, and molten steel per ton adds refining alumina balls 150 ~ 200kg.
5. according to high strength carbonized Gear Steel 19CrNi5 production method according to claim 1, it is characterized in that, in the refining of LF stove, whole process carries out Bottom Argon Stirring, ladle controls 0.4 ~ 0.6MPa to argon gas during furnaceman LF position, heat up and argon gas control in refining period 0.4 ~ 0.6MPa, quiet Argon stage argon gas controls 0.1 ~ 0.3MPa, ladle enters LF station, adopt 20000 ~ 25000A big current intensificationization slag, when top of the slag fluctuation, when molten steel and electric arc are not exposed, add quickened lime, 200 ~ 300kg is added in per ton, after 5min first time sampling analysis chemical composition, alloy is added according to chemical composition target value, and carburetting, alloy and carbon dust should be added in argon gas stream, to promote alloy and carbon dust rapid melting and homogenizing.
6. according to high strength carbonized Gear Steel 19CrNi5 production method according to claim 5, it is characterized in that, add diffusion deoxidizer 1 ~ 3kg/t when liquid steel temperature reaches 1600 ~ 1610 DEG C and carry out diffusive deoxidation, close fire door 10min, the second time sampling analysis chemical composition when liquid steel temperature reaches 1610 ~ 1620 DEG C of temperature, to confirm the deviation value that each chemical element component content requires apart from target value, after secondary sample is taken away, add diffusion deoxidizer and continue residue adjustment, add reductor total amount 1 ~ 2kg/t, slag basicity pH value is kept to be 2.5 ~ 3.5, viscosity coefficient of dross 0.80 ~ 1.20Pas, continue to keep melting under a white slag 20 ~ 30min simultaneously, when liquid steel temperature reaches 1670 ~ 1700 DEG C, during chemical composition ranges, carry out final deoxygenation and feed Al line 0.5 ~ 1.0kg/t, Ca-Si line 2.0 ~ 2.5kg/t is fed after feeding Al line 3min, line feeding terminates the quiet Argon of rear beginning, hold-time 10 ~ 20min.
7. according to high strength carbonized Gear Steel 19CrNi5 production method according to claim 1, it is characterized in that, VD stove refining argon pressure before vacuum pump starts controls 0.1 ~ 0.3MPa, not exposed with top of the slag fine motion molten steel, start timing when vacuum tightness reaches 100Pa, hold-time 10 ~ 15min, is adjusted to 0.3 ~ 0.5MPa by argon pressure simultaneously, after quiet Argon terminates, in per ton, evenly add carbonization rice husk heat preserving agent 40 ~ 80kg.
8. according to high strength carbonized Gear Steel 19CrNi5 production method according to claim 1, it is characterized in that, 3 machines 3 are adopted to flow curved type continuous caster continuous casting steel billet in continuous casting, continuous casting head stove bull ladle temperature 1592 ~ 1602 DEG C, the 2nd stove bull ladle temperature 1575 ~ 1585 DEG C, 3rd stove is to tail stove bull ladle temperature 1565 ~ 1575 DEG C, total casting sequence 8 ~ 10 stove, pulling rate 0.80 ~ 0.85m/min, continuous casting head stove superheating temperature 30 ~ 35 DEG C, 2nd stove to 20 ~ 30 DEG C, tail stove, crystallizer discharge 160M
3/ h, secondary cooling water specific water 0.30L/g, electricity stirs electric current 360A, straightening temperature 950 ~ 980 DEG C.
9., according to high strength carbonized Gear Steel 19CrNi5 production method according to claim 1, it is characterized in that, in the heating phase, setting preheating section furnace temperature 500 ~ 750 DEG C, heat-up time 45 ~ 50min; Heating zone is divided into heating one section and two periods two stages, heats two sections of heat-up rates, 300 ~ 330 DEG C/h, heats one section of heat-up rate, 140 ~ 170 DEG C/h, heating secondary reformer temperature 1060 ~ 1080 DEG C, heat-up time 60 ~ 65min, heating primary reformer temperature 1220 ~ 1230 DEG C, heat-up time 55 ~ 60min; Soaking zone furnace temperature 1200 ~ 1220 DEG C, soaking time 60 ~ 90min, steel billet tapping temperature 1180 ~ 1200 DEG C, total heat-up time 220 ~ 265min.Be oxidizing atmosphere in heating period and soaking beforehand control stove, the soaking later stage is neutral or micro-reducing atmosphere.
10. according to high strength carbonized Gear Steel 19CrNi5 production method according to claim 1, it is characterized in that, rolling sequence adopts reversing two high blooming mill roughing, start rolling temperature 1100 ~ 1150 DEG C, finishing temperature 900 ~ 950 DEG C, enters to cheat temperature 600 ~ 650 DEG C, soaking time 36 ~ 48h, play temperature≤150 DEG C, hole, cooling in heap temperature 300 ~ 500 DEG C, each stack weight 40 ~ 80 tons.
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| CN105177448A (en) * | 2015-10-26 | 2015-12-23 | 江苏保捷锻压有限公司 | Automobile manual transmission spiral bevel gear material and liquid forging technique thereof |
| CN106021721A (en) * | 2016-05-19 | 2016-10-12 | 山东科技大学 | Carburizing cylindrical gear parameterized simulation and analysis method and CAE system |
| CN107164605A (en) * | 2017-03-29 | 2017-09-15 | 河钢股份有限公司承德分公司 | A kind of LF refining method of deoxidation for producing low-carbon welding wire steel |
| CN108581398A (en) * | 2018-04-28 | 2018-09-28 | 浙江恒利五金科技有限公司 | A kind of high-precision automobile gear and its forging method |
| CN109371332A (en) * | 2018-02-02 | 2019-02-22 | 宝钢特钢长材有限公司 | A kind of 16MnCrS5 pinion steel and its production method |
| CN109454211A (en) * | 2018-11-26 | 2019-03-12 | 抚顺特殊钢股份有限公司 | The method of electric furnace smelting high quality pinion steel |
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