CN102732804B - Bainite steel frog and manufacture method thereof by three-stage cooling after rolling - Google Patents
Bainite steel frog and manufacture method thereof by three-stage cooling after rolling Download PDFInfo
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- CN102732804B CN102732804B CN201210194847.9A CN201210194847A CN102732804B CN 102732804 B CN102732804 B CN 102732804B CN 201210194847 A CN201210194847 A CN 201210194847A CN 102732804 B CN102732804 B CN 102732804B
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Abstract
The invention discloses a bainite steel frog, comprising 0.18-0.23 wt% of C, 1.0-2.0 wt% of Mn, 0.4-0.7 wt% of Al, 0.6-1.0 wt% of Ni, 1.4-2.0 wt% of Cr, 1.0-1.6 wt% of Si, less than 0.01 wt% of Ti, less than 0.0005 wt% of B, less than 0.03 wt% of V, less than 0.01 wt% of Nb, less than 0.0016 wt% of O, less than 0.0001 wt% of H, less than 0.01 wt% of S, and less than 0.01wt% of P, and the balance of Fe A method for manufacturing the bainite steel frog comprises the following steps: smelting in an oxygen converter; then conducting external refining; and then forming sectional form by continuous casting and hot rolling to obtain a railway frog blank material, wherein the rolling ratio is larger than 9; after rolling, directly conducting three-stage cooling to room temperature; and finally heating up to 310-330 DEG C, preserving the heat for 50-70min, and then conducting air cooling to room temperature. According to the invention, the advantages of simple process, low cost, energy saving performance and material saving performance are achieved, and the bainite steel frog has excellent welding performance.
Description
Technical field
The present invention relates to the special bainitic steel of a kind of ferrous materials and manufacture method thereof, particularly railroad frog and manufacture method thereof.
Background technology
ZGMn13 Hadfield Steel is that Britain slip-stick artist Hadfield invented in September, 1882, its first purposes is exactly for making the railway frog of tramway in 1892, from then on, over more than 100 year, nearly all railroad frog is all to be made by this material in the world.The chemical composition of the ZGMn13 that initial Hadfield announces is: C1.35%, Si0.69%, Mn12.76%.At present, the chemical composition scope of generally acknowledged ZGMn13 steel is C1.0～1.4%, Mn11～14%, and all the other are that iron and a small amount of impurity are as Si, S, P etc.The average overload quantity (work-ing life) of the ZGMn13 steel railway frog that China produces is 1.5 hundred million tons, and can reach more than 200,000,000 tons the mean life of the ZGMn13 steel railway frog that the U.S. and some developed countries of Europe produce.Along with the raising of social development and transportation by railroad speed, people are to the higher requirement of railroad frog proposition in work-ing life.Therefore from the former ZGMn13 steel of further raising railway frog work-ing life with seek the aspects such as new railway frog material and launched research widely, there are many new achievements in research in people.As world patent WO0136698, Canadian Patent CA2159358, United States Patent (USP) 4514235, Chinese patent CN02157927.X and 98124899.3 etc.Make a general survey of these achievements in research and practical effect, can say at present and mainly contain two major sects about railroad frog selection aspect in the world, first Hadfield Steel utilizes the processing methodes such as metallurgy, casting, thermal treatment and mechanical enhancer further to improve its work-ing life on the basis of original high mangaenese steel; It two is that Main Tissues is the middle low-carbon low-alloy steel of bainite.
Bainitic steel is because it has high intensity, suitable toughness and hardness makes it show good anti-contact fatigue and wear resisting property, especially it has excellent welding technological properties, makes it become one of ideal material of making by novel load-carrying railway frog used for high-speed railway.Therefore, it is having application more and more widely aspect making railroad frog at present.Chinese patent CN02157927.X has announced the compound central body of frog of a kind of bainitic steel electroslag casting, and its heart rail main alloy element is Si, Mn, Cr, Mo, Ni, is accompanied by micro-V and Nb, and all the other are Fe.Chinese patent 98124899.3 is announced a kind of railroad frog proprietary material, inventor is tough the special superelevation of its called after railroad frog weldable air-cooled great health bainitic steel, this invents taking Mn, Si as main alloy element, be aided with the elements such as Cr, Ni, Mo, after austenitizing, air cooling can arrive Bainite/Martensite Dual-Phase tissue; Its Essential Chemistry composition is that (Wt%): C 0.10～0.65, Si≤2.65, Mn 0.50～3.20, Cr0.20～2.80, Ni≤3.50, Mo≤2.00, remainder are Fe.Another achievement in research of our country has been reported " high-performance novel steel alloy novel material of new generation ", it is taking Si and Mn as main alloy element, Cr, Mo, Ni are auxiliary, be aided with Re, V, the rotten railway switch heart rail of Ti, specific chemical composition is: 0.25～0.4%C, 1.0～2.5%Si, 1.0～2.5%Mn, 1.0～2.0%Cr, 0.3～0.8%Mo, 0.3～1.0%Ni, and Re, B, V, the Ti of trace.The forging method moulding of this steel, normalizing or annealed state obtain bainite structure.Under use state, the mechanical performance index of steel is: tensile strength sigma
b1240～1360MPa, yield strength σ
s>=1100MPa, unit elongation δ
5>=8%, room temperature impelling strength>=75J/cm
2, low-temperature impact toughness>=40J/cm
2(40 DEG C), hardness HRC37～42.
Other several countries of the world have also successively carried out the research of bainite steel frog, and its achievement in research is as shown in table 1.Can find out, external Mo system or the Mo-B of having selected on the Composition Design of bainite steel frog is associated gold, taking Mo or Mo-B as basal component, adds other alloying elements, the advantage of this Composition Design is to be convenient to obtain bainite structure under air cooling condition, and technique is simple.Because in the time containing the Mo element of q.s in steel, can obviously postpone perlitic transformation and ferritic transformation.Add after B element, act on more obviously, bainite transformation " C " curve is protruded left, thereby can obtain bainite structure within the scope of wider cooling rate.This by alloying, and the thinking that obtains bainite structure under air cooling condition becomes the main flow of current bainite steel frog research.From result, various countries' steel used has all obtained more satisfied Microstructure and properties after air cooling.External air-colled bainite tissue is mostly mixed structure or carbide-free Bainite tissue.Table 2 has been listed the mechanical property of various countries' business bainitic frog steels, can find out that the bainite steel frog that various countries adopt all has higher intensity, toughness and hardness.
Table 1 is primary commercial bainite steel frog chemical composition (wt%) both at home and abroad
| Country | C | Mn | Si | Cr | Ni | Mo | B | Other |
| Britain | 0.1 | 1.0 | - | 2.0 | 3.0 | 0.5 | 0.003 | |
| The U.S. | 0.26 | 1.85 | 1.75 | - | 3.00 | 0.50 | 0.004 | |
| Germany | 0.4 | 0.7 | 1.5 | 1.1 | - | 0.8 | 0.1V | |
| Japan | 0.2-0.55 | 0.4-2.5 | 0.15-1.0 | 0.2-3.0 | - | 0.1-2.0 | 0.1Nb0.1V | |
| China | 0.3 | 1.5 | 1.5 | 1.5 | 0.5 | 0.5 | - |
The mechanical property of the several national business bainite steel frogs of table 2
| Country | σ s（MPa） | σ b（MPa） | δ（％） | Hardness |
| Britain | 750 | 1000 | 6 | 350HB |
| The U.S. | 1000 | 1531 | 5 | 450HB |
| Germany | 1037 | 1455 | 13 | 440HV |
| China | - | ≥1240 | - | 38-45HRC |
Wherein, the nickel of 3wt% is all contained in the U.S. and Britain, and cost is higher, and the plasticity of material is lower simultaneously; Germany because carbon content is higher, and welding property is very poor; The not successful Application in practice of Japan; The unstable properties of China.
Summary of the invention
The object of the invention is to improve that a kind of manufacturing process is simple, with low cost, energy-saving material-saving, intensity are high, three sections of cooling manufacture method after the bainite steel frog of good toughness and rolling thereof.The present invention adopts smelting to Clean Steel, rolls that rear control is cooling, Final Heat Treatment Process obtains the special pure bainitic steel of low-carbon (LC) of novel wear resistant antifatigue railroad frog.
The bainitic steel that railroad frog of the present invention is special, its chemical composition (wt%) is: C 0.18～0.23, Mn 1.0～2.0, Al 0.4～0.7, Ni 0.6～1.0, Cr 1.4～2.0, Si 1.0～1.6, Ti < 0.01, B < 0.0005, V < 0.03, Nb < 0.01, O < 0.0016, H<0.0001, S<0.01, P<0.01, all the other are Fe.
The manufacture method of the special bainitic steel of above-mentioned railroad frog:
1, smelt: relevant material industry pure iron, ferronickel, ferrochrome, ferromanganese, commercial-purity aluminium etc. are put into oxygen coverter smelting molten steel, then molten steel is carried out to external refining.
2, cast: above-mentioned molten steel is carried out to continuous casting at 1550～1600 DEG C and become steel billet.
3, rolling: above-mentioned continuous casting steel billet is carried out to hot rolling, 1100～1150 DEG C of start rolling temperatures, 860～920 DEG C of finishing temperatures, are rolled into strand the size that approaches railroad frog heart rail and wing rail, and rolling ratio is greater than 9.
4, cooling: by the railway frog after above-mentioned rolling carry out three sections cooling, more than 450 DEG C, temperature speed of cooling is 50～80 DEG C/min, between 450～300 DEG C, temperature speed of cooling is 1.5～2.5 DEG C/min, 300 DEG C of following temperature naturally cooling in air.
5, thermal treatment: after above-mentioned cooled railway frog is heated to 310～330 DEG C of insulation 50～70min, air cooling is to room temperature.
The present invention compared with prior art tool has the following advantages:
1, because this manufacture method is to utilize rolling to obtain to approach bainite steel frog heart rail and wing rail size, follow-up machining amount is little, simultaneously, it is to utilize to roll rear control cooling process and obtain desirable tissue and performance, reaustenitizing processing again, therefore, technique is simple, with low cost, energy-saving material-saving, and cost is more than 50% compared with forging bainite steel frog.
2, owing to being to utilize to roll rear control cooling process technology, thickness and the size of the original austenite grains size in the bainitic steel obtaining and bainite ferrite and residual austenite sheet are all less, and it uses condition mechanical performance: σ b>=1250MPa, σ s>=1000MPa, δ 5>=10%, a
kU>=80J/cm
2, a
kU(-40 DEG C)>=50J/cm
2, HRC38～43.
3, the content that the present invention finds micro impurity element is to having a huge impact the work-ing life of bainite steel frog, thereby strictly limited the content of micro impurity element.Therefore, the comprehensive mechanical property of the bainite steel frog of this manufacture method manufacture is higher than heat-treating the bainite steel frog performance that manufacture method obtains after forging again, especially toughness.
4, can suitably reduce the carbon content in bainitic steel, also can obtain exceeding the performance of commercial widely used higher carbon content bainite steel frog at present, therefore, the welding technological properties of bainite steel frog of the present invention is good.
Brief description of the drawings
Fig. 1 is bainite steel frog stock section form sketch of the present invention.
Embodiment
Embodiment 1
First relevant material industry pure iron, ferronickel, ferrochrome, ferromanganese, commercial-purity aluminium etc. are put into oxygen coverter and smelt into molten steel, then utilize LF stove to carry out external refining to molten steel, utilize RH method to carry out Fruit storage to molten steel.Molten steel is carried out to continuous casting at 1550 DEG C and become steel billet, the chemical composition (wt%) of this steel billet is: C 0.20, Mn 1.10, Al 0.50, Ni 0.62, Cr 1.92, Si 1.50, Ti 0.008, B 0.0003, H 0.00008, V 0.0011, Nb 0.008, O 0.0012, S 0.006, P 0.003, all the other are Fe.Then above-mentioned continuous casting steel billet is carried out to cogging hot rolling, rolling ratio is 13,1140 DEG C of start rolling temperatures, and 920 DEG C of finishing temperatures, being rolled into section form is the railway frog material that is similar to rail shape section shape, as shown in Figure 1.The railway frog of rolling is rolled and carries out three sections of cooling process, and more than 450 DEG C, temperature speed of cooling is 50 DEG C/min, and between 450～300 DEG C, temperature speed of cooling is 1.5 DEG C/min, 300 DEG C of following temperature naturally cooling in air.After finally above-mentioned cooling railway frog being heated to 320 DEG C of insulation 60min, air cooling is to room temperature.Below rail head top layer, 20mm depth is got longitudinal test piece test, and mechanical property is: σ
b=1310MPa, σ
0.2=1105MPa, δ
5=14%, a
kU=121J/cm
2, a
kU(-40 DEG C)=59J/cm
2, HRC41.
Embodiment 2
First relevant material industry pure iron, ferronickel, ferrochrome, ferromanganese, commercial-purity aluminium etc. are put into oxygen coverter and smelt into molten steel, then utilize LF stove to carry out external refining to molten steel, utilize RH method to carry out Fruit storage to molten steel.Molten steel is carried out to continuous casting at 1600 DEG C and become steel billet, the chemical composition (wt%) of continuous casting steel billet is: C 0.19, Mn 1.86, Al 0.68, Ni 0.75, Cr 1.48, Si1.15, Ti 0.009, B 0.0001, H0.00009, V 0.009, Nb 0.005, O 0.0010, S 0.008, P 0.009, all the other are Fe.Then the firm base of continuous casting is carried out to cogging hot rolling, rolling ratio is 14,1130 DEG C of start rolling temperatures, and 900 DEG C of finishing temperatures, being rolled into section form is the railway frog material that is similar to rail profile shape, as shown in Figure 1.The railway frog of rolling is rolled and carries out three sections of cooling process, and more than 450 DEG C, temperature speed of cooling is 65 DEG C/min, and between 450～300 DEG C, temperature speed of cooling is 2.5 DEG C/min, 300 DEG C of following temperature naturally cooling in air.After finally above-mentioned cooling railway frog being heated to 310 DEG C of insulation 70min, air cooling is to room temperature.Below rail head top layer, 20mm depth is got longitudinal test piece test, and mechanical property is: σ
b=1260MPa, σ
0.2=1030MPa, δ
5=16%, a
kU=138J/cm
2, a
kU(-40 DEG C)=71J/cm
2, HRC40.
Embodiment 3
First relevant material industry pure iron, ferronickel, ferrochrome, ferromanganese, commercial-purity aluminium etc. are put into oxygen coverter and smelt into molten steel, then utilize LF stove to carry out external refining to molten steel, utilize RH method to carry out Fruit storage to molten steel.Molten steel is carried out to continuous casting at 1580 DEG C and become steel billet, the chemical composition (wt%) of this continuous casting steel billet is: C 0.22, Mn 1.65, Al 0.52, Ni 0.92, Cr 1.67, Si1.31, Ti 0.006, B 0.0003, H 0.00007, V 0.0013, O 0.0011, S 0.009, P 0.008, Nb0.003, all the other are Fe.Then above-mentioned continuous casting steel billet is carried out to cogging hot rolling, rolling ratio is 11,1100 DEG C of start rolling temperatures, and 860 DEG C of finishing temperatures, being rolled into section form is the section railway frog material that is similar to rail shape, as shown in Figure 1.Railway frog after rolling is rolled and carries out three sections of cooling process, and more than 450 DEG C, temperature speed of cooling is 80 DEG C/min, and between 450～300 DEG C, temperature speed of cooling is 2.0 DEG C/min, 300 DEG C of following temperature naturally cooling in air.After finally above-mentioned cooled railway frog being heated to 330 DEG C of insulation 50min, air cooling is to room temperature.Below rail head top layer, 20mm depth is got longitudinal test piece test, and mechanical property is: σ
b=1340MPa, σ
0.2=1100MPa, δ
5=12%, a
kU=107J/cm
2, a
kU(-40 DEG C)=52J/cm
2, HRC42.
Claims (1)
1. three sections of cooling manufacture method after a bainite steel frog rolling, the chemical composition mass percent wt% of this bainite steel frog is: C 0.18～0.23, Mn 1.0～2.0, Al 0.4～0.7, Ni 0.6～1.0, Cr 1.4～2.0, Si 1.0～1.6, Ti < 0.01, B < 0.0005, V < 0.03, Nb < 0.01, S<0.01, P<0.01, all the other are Fe, in steel, minimum gas elemental oxygen and hydrogen richness are controlled at very low level, O < 16ppm, H<1ppm, relevant material industry pure iron, ferronickel, ferrochrome, ferromanganese, commercial-purity aluminium are put into oxygen coverter smelting molten steel, then molten steel is carried out to external refining, above-mentioned molten steel is carried out to continuous casting at 1550～1600 DEG C and become steel billet, it is characterized in that: above-mentioned continuous casting steel billet is carried out to hot rolling, 1100～1150 DEG C of start rolling temperatures, 860～920 DEG C of finishing temperatures, rolling ratio is greater than 9, continuous casting steel billet is rolled into the size that approaches railroad frog heart rail and wing rail, by the railway frog after the rolling carry out three sections cooling, more than 450 DEG C, temperature is cooling with 50～80 DEG C/min speed of cooling, between 450～300 DEG C, temperature is cooling with 1.5～2.5 DEG C/min speed of cooling, 300 DEG C of following temperature naturally cooling in air, by above-mentioned cooled railway frog, reheat 310～330 DEG C insulation 50～70min after air cooling to room temperature.
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| CN102936700B (en) * | 2012-10-30 | 2014-07-23 | 燕山大学 | Full bainitic steel frog and manufacturing method thereof |
| CN111618215A (en) * | 2019-02-28 | 2020-09-04 | 浙江德盛铁路器材股份有限公司 | Integrated forming processing technology of variable cross-section parts |
| CN112647011B (en) * | 2020-12-19 | 2022-07-26 | 台州学院 | Preparation method of fine-grain high-strength and high-toughness bainitic steel |
| CN113755670B (en) * | 2021-08-24 | 2022-10-25 | 中铁宝桥集团有限公司 | Quenching and cooling method for bainitic steel frog point rail |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0804623B1 (en) * | 1995-01-20 | 2004-03-24 | Corus UK Limited | Method for producing carbide-free bainitic steels |
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| JP4177539B2 (en) * | 2000-03-28 | 2008-11-05 | 新日本製鐵株式会社 | Manufacturing method of laser welding steel |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0804623B1 (en) * | 1995-01-20 | 2004-03-24 | Corus UK Limited | Method for producing carbide-free bainitic steels |
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| JP特开2001-279324A 2001.10.10 |
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