CN1014080B - Niobium-containing high strength fishing - Google Patents
Niobium-containing high strength fishingInfo
- Publication number
- CN1014080B CN1014080B CN 88101251 CN88101251A CN1014080B CN 1014080 B CN1014080 B CN 1014080B CN 88101251 CN88101251 CN 88101251 CN 88101251 A CN88101251 A CN 88101251A CN 1014080 B CN1014080 B CN 1014080B
- Authority
- CN
- China
- Prior art keywords
- niobium
- steel
- splice bar
- present
- temperature
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Abstract
The present invention belongs to niobium containing and high strength fishing fish plate steel for railroads. The steel of the present invention has the chemical components by the weight percentage of 0.50 to 0.62 % of C, 0.20 to 0.40 % of Si, 0.50 to 0.80 % of Mn, at most 0.040% of P, at most 0.045% of S and 0.015 to 0.050 % of Nb, wherein the optimal content of C is from 0.50 to 0.57 %, the optimal content of Mn is from 0.65 to 0.80% and the optimal content of Nb is from 0.020 to 0.040 %. In the heat treating technology, the heating temperature of the rolled material of the fish plate steel is from 1140 to 1180 DEG C; the quenching temperature is from 860 to 890 DEG C and the optimum temperature is from 870 to 880 DEG C; the self tempering temperature is from 560 to 580 DEG C. The steel of the present invention has the advantages of low alloy content and simple manufacturing technology, and the mechanical property achieves the world advanced level at present.
Description
The technology of the present invention belongs to railway structural steel.
Our times various countries railway transportation all develops towards the direction of high speed, heavy duty, big volume of freight.In order to adapt to the requirement of this development, railway rail is significantly improved performance and quality by low alloying and suitable thermal treatment means, has begun to develop σ at present
b〉=1300MPa level, specification have reached the novel rail of 75kg/m.
As the splice bar of the connection fittings of railway track, in service at rail vehicle is accepted the mechanical load of multiple complexity such as tensile, compressive, bending song, is one of weak link of railway member.The research of splice bar should be carried out synchronously along with the research of railway track, is complementary in the hope of the development with railway track, yet but is not subjected to the due attention of people always.Even abroad, though use the low alloy steel rail in a large number, splice bar still rests on the carbon steel level, and intensity generally is lower than rail, thereby work-ing life is also not as good as rail.
Present world major industrial country, as the splice bar that states such as English, the U.S. and Russia, method, day produce, its material all is the higher medium carbon steel of manganese content, hot rolling or as-heat-treated condition are used.Wherein the splice bar of the Soviet Union is through modifier treatment, and therefore, the overall target level of its strong plasticity is the highest, occupy first place in the world, but work-ing life is also not as good as rail.
The chemical ingredients and the mechanical property of the splice bar that external major industrial country produces are listed table 1 and table 2 respectively in.
The main manufacturer of the railway splice bar of China is the medium-sized Steel Mill of Anshan iron and steel plant.Included standard in
Major industrial country's splice bar Chemical Composition table 1
Country origin standard chemical composition (%)
C Si Mn P S
Soviet Union Γ OCT4133-73 can reach 0.62 can reach 1.00≤0.045≤0.050
U.S. ASTMA49-68 0.35～0.60 can reach 1.00≤0.040
ASTMA5-68 ≥0.45 ≤0.040
Japan JISE1102-78 0.40～0.55≤0.40 0.55～1.00≤0.04≤0.045
JRSO22024c-67 0.40～0.55 ≤0.40 0.55～1.00 ≤0.040 ≤0.045
Britain BS47-1959 0.30～0.42≤0.15≤0.08≤0.075≤0.075
Major country's splice bar mechanical property table 2
Country origin standard σ
sσ
bδ
5ψ HB clod wash (°)
（MPa） （MPa） （%） （%） d＝3a
Soviet Union Γ OCT4133-73 〉=530 〉=845 〉=10 〉=30 235～388 20
U.S. ASTMA49-68 〉=490 〉=685 〉=12 〉=25 90
ATMA5-68 ≥585 ≥15
Japan JISE1102-78 〉=685 〉=12 262～331
JRSO22024c-67 ≥685 ≥12
Britain BS49-1959 560～645 〉=20
38kg/m, 43kg/m, three kinds of specifications of 50kg/m are arranged.Standard No. YB354-63.Also manufactured experimently out two kinds of new spec products of 60kg/m, 75kg/m in 1978 and 1986 respectively.
The grade of steel of the splice bar that China produces be general carbon steel B7 through quenching, use after the waste heat auto-tempering.The salient features of YB354-63 regulation is σ
b〉=785MPa.δ
5〉=9%, HB=227～388, clod wash α=30 °, d=3a are intact.Because general carbon steel causes easily that in second-heating grain coarsening and Q-tempering tissue to the susceptibility of technology, make that existing B7 splice bar performance is on the low side, and fluctuation is bigger.In actual production, the seconds rate is also higher.Therefore, though the social demand amount is bigger, manufacturer can only be controlled on output, carries out producing limitedly, causing the Ministry of Railways will use up more than 500 ten thousand yuan of foreign exchanges every year from more than 10,000 ton of splice bar of state's imports such as Japan, to satisfy the needs of railway.
On the other hand, because existing splice bar performance is on the low side, be not complementary with the low alloy steel rail.Just began the saddle-shape distortion in use 2 years, or rupture.Its, average out to was about 6 years in work-ing life, approximately was 1/2nd of carbon element rail, and 1/3rd of low alloy steel rail has become a big expendable part of railway track.The Ministry of Railways is for changing splice bar, and only materials cost will be used up more than 400 ten thousand yuan in every year.
Purpose of the present invention is exactly the means by microalloying, fundamentally improves the material of splice bar with steel, and is aided with the thermal treatment process that adapts with it, improves the over-all properties of splice bar intensity and plasticity, makes it to be complementary with railway rail.Splice bar performance provided by the present invention can reach the international advanced standard level.
Splice bar manufacture method provided by the present invention is as alloy element medium carbon steel to be carried out microalloying with niobium.Up to now, carried out many research work to containing the niobium steel both at home and abroad, but all be in low-carbon steel or high carbon steel, to add niobium, and be mostly that elements compounding such as niobium and manganese, molybdenum, vanadium, titanium add in the steel.Carry out alloying as for single adding niobium in the medium carbon steel,, still do not have report both at home and abroad according to the retrieval of carrying out at present.Therefore, determining the add-on of trace niobium in the medium carbon steel, is an important content of the present invention.
As the niobium in the alloying element adding steel, be strong carbide, nitride forming element, in steel, form very stable compound N bC, NbN, Nb
2C, Nb(CN).Even these stable compounds do not still have part molten and be present on the austenitic matrix in being heated to 1100 ℃ austenite region, grow up thereby play a part to hinder austenite crystal.When temperature reduced, the part niobium that is dissolved in the austenite was constantly separated out formation (NbCN), and becoming austenitic transformation is ferritic core.Above-mentioned two kinds of effects of niobium have all promoted austenitic transformation product ferrite and pearlitic structure refinement, and the NbC or the Nb(CN that separate out in the cooling) brought into play the precipitation strength effect simultaneously.In addition, the effect of the crystal grain thinning that adding produces of niobium also will have significantly the plasticity of steel and to improve.
Show that through test of many times content of niobium of the present invention was controlled at 0.02～0.04% o'clock, have best reinforcement ability.If when niobium content continued to increase, then strengthening effect weakened on the contrary.For yield tensile ratio, when niobium content greater than 0.02% the time, the yield tensile ratio maximum is when niobium content continues to increase.Yield tensile ratio does not have considerable change.According to this result, in existing general carbon steel splice bar, add 0.02～0.04% niobium, its yield-point is by σ
s〉=520MPa is increased to 624MPa, tensile strength σ
bReach 867MPa by 624MPa.Intensity has reached design objective, i.e. Soviet Union's standard gauge definite value, σ
5〉=530MPa, σ
b〉=845MPa.Take all factors into consideration factors such as production, performance requriements, the chemical ingredients that contains the niobium splice bar of the present invention is C0.50～0.62%, optimum content is 0.50～0.57%, Si0.20～0.40%, Mn0.50～0.80%, and optimum content is 0.65～0.80%, P≤0.040%, S≤0.045%, Nb:0.015～0.050%.Optimum content is 0.02～0.04%.
Owing to add niobium in the steel, must cause the corresponding change of transformation temperature, cooling transformation curve, must cause the respective change of heat treating regime.In order to give full play to crystal grain thinning and the precipitation strength effect of alloying elements nb in steel, also corresponding heat treating regime must be arranged.Therefore, establish that to contain niobium splice bar rational heat treatment technology be another important content of the present invention.
Steel heats in the austenitic area, has to reduce the trend that grain boundary area becomes steady state.Therefore, Heating temperature raises, and crystal grain will be grown up.Contain the niobium steel about 0.05%, its austenite alligatoring temperature can exceed about 200 ℃ than the carbon steel of no niobium, even be heated to 1100 ℃, still can keep crystal grain that alligatoring does not take place.In the actual production, to enhance productivity, contain niobium fish tail slab stocking Heating temperature and allow to reach 1180 ℃ as the method that adopts rapid heating.
Because niobium is the strong carbide forming element, niobium adds the A that can improve steel in the steel
3Point, and continuous cooling curve is moved right.Workpiece temperature when quenching temperature that control is suitable and water outlet is to make splice bar obtain the key of favorable tissue and face shaping.Through test of many times, determine that the suitable heat treatment technology that contains the niobium splice bar is: quenching temperature: 860～900 ℃, optimum temps is 870～880 ℃; Self tempering temperature: 560～580 ℃, after the thermal treatment, the metallographic structure of splice bar is that sorbite adds a little ferrite.
According to chemical ingredients that contains the niobium splice bar and thermal treatment process, can make its production technique.Produce by this production technique, just can obtain splice bar of the present invention.
This fish tail slab can be at basic open-hearth furnace or converter smelting.Open hearth can adopt top blast oxygen technology, and converter can be adopted top bottom blowing, and operation is undertaken by general carbon steel in the stove, but finished product phosphorus sulphur content should be controlled at P≤0.040%, S≤0.045%, and tapping temperature is 1600～1620 ℃.In tapping,, begin killing Fe-Mn successively when molten steel impouring steel teeming ladle three/for the moment, Fe-Si, its quantity is pressed the chemical ingredients interpolation of steel, adds Al at last, and adding the Al amount is 300 gram/tons.Reductor adds the back and adds Fe-Nb, and the rate of recovery of Nb can be calculated by 80%.The smelting component that contains niobium fish tail slab is controlled by aforementioned invention predetermined component.The cast ingot shape is Jb8.0 or Jc7.8, or the specification of other adaptation.
Steel ingot heat is sent the rough rolling mill, rolls into 136mm or 145mm square billet through the blooming mill cogging.The Heating temperature of steel billet formation rolling is 1050～1150 ℃, and burned steel billet rolls into fish tail lath steel through roller mill.The technology of the rolling splice bar that contains niobium is identical with the normal carbon splice bar, abnormal conditions can not occur in rolling.
Shove charge is heated after containing niobium fish tail lath steel fixed ruler cold shear on request, and Heating temperature is 1140～1180 ℃.Be 20 minutes total heat-up time.Punching in time after steel billet is come out of the stove.Quench after the punching.Temperature before the entry should be controlled at 860～900 ℃, and the residence time is 60 seconds in water, and the steel part leaving water temperature(LWT) should be controlled at 560～580 ℃.Splice bar after the thermal treatment, by the technology of general carbon steel splice bar carry out cold rectify to deburr etc. be finished product.
Major advantage of the present invention is to adopt niobium reliable as theory and experiment basis that single alloying element carries out alloying.Alloy series is simple, is convenient to control.The alloying element consumption is few, only adds 0.015～0.050% niobium in the steel, and cooperates the significantly raising of performance acquisition that just can make splice bar with corresponding heat treating regime, and production cost has only very little increase, the benefit of steel mill is 200 yuan/ton, and by producing 40000 tons of calculations per year, a year benefit can reach 8,000,000 yuan.Implement the present invention and need not special process, need not acquire specific installation, thereby the present invention is convenient to be applied aborning and promote.
The comprehensive mechanical performance of producing by method of the present invention that contains the niobium splice bar can reach world-class levels, i.e. the level of Soviet Union's splice bar Γ OCT4133 standard: σ
s〉=530MPa, σ
b〉=845MPa, δ
s〉=10%, ψ 〉=30%, HB are 235～388, clod wash α=20 °, and d=3a is qualified.The performance of splice bar of the present invention is significantly improved than the performance of the existing general carbon steel splice bar of present China.Therefore, as with YB354-63 as acceptance conditions, qualification rate can reach 100%.Because the σ of this steel
bAt least improve 60MPa than general carbon steel splice bar, and because S.P reduces by 0.005% respectively, and steel is further purified, and will be significantly improved work-ing life, this will create very big social benefit for the user.After output enlarged, the Ministry of Railways will be to state's outer vent.
One embodiment of the present of invention are to produce the 50kg/m rail with containing 150 tons of niobium splice bars totally two batches of products, test at railway place, Jiyuan, Henan and Shenyang Railway Bureau respectively.The smelting component of product is listed in table 3, and mechanical property is listed in table 4.And contrast with YB354-63 and Γ OCT4133.As can be seen from Table 4, the niobium splice bar that contains provided by the present invention, its performance is significantly improved than existing domestic standard YB354-63.Also improve a lot than state's standards such as U.S., day, English, reached every index of the advanced standard Γ OCT-4133 defined of present world splice bar.
Embodiments of the invention contain the actual constituent table 3 of niobium splice bar
Embodiment chemical ingredients (%)
C Si Mn P S Nb
First example 0.54 0.26 0.60 0.014 0.033 0.023
Second example 0.53 0.28 0.68 0.013 0.032 0.038
Embodiments of the invention contain the actual machine performance table 4 of niobium splice bar
Data Source σ
sσ
bδ
5υ HB clod wash (°)
（MPa） （MPa） （%） （%） d＝3a
YB354-63 〉=520 〉=785 〉=9 〉=20 277～388 30 are qualified
Γ OCT4133-73 〉=530 〉=845 〉=10 〉=30 235～388 20 are qualified
It is qualified to contain niobium the 1st example 595 900 14 44 274 30
Splice bar the 2nd example 625 955 15 42 301 30 is qualified
Claims (4)
1, a kind of ferro-niobium road fish tail slab that contains is characterized in that chemical ingredients (%) is C0.50-0.57, Si0.20-0.40, Mn0.50-0.80, P≤0.040, S≤0.045, Nb0.015-0.050, and all the other are iron.
2, the described a kind of ferro-niobium road fish tail slab that contains of claim 1, the optimum content (%) that it is characterized in that niobium is 0.020-0.040.
3, the described a kind of ferro-niobium road splice bar Heat Treatment Of Steel system that contains of claim 1, the quenching temperature that it is characterized in that the splice bar stocking is 860-900 ℃, and the residence time is 60 seconds in quenchant water, and self tempering temperature is 560-580 ℃.
4, the described a kind of ferro-niobium road splice bar Heat Treatment Of Steel system that contains of claim 3, the optimum range that it is characterized in that quenching temperature is 870-880 ℃.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 88101251 CN1014080B (en) | 1988-03-08 | 1988-03-08 | Niobium-containing high strength fishing |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 88101251 CN1014080B (en) | 1988-03-08 | 1988-03-08 | Niobium-containing high strength fishing |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1035682A CN1035682A (en) | 1989-09-20 |
| CN1014080B true CN1014080B (en) | 1991-09-25 |
Family
ID=4831682
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 88101251 Expired CN1014080B (en) | 1988-03-08 | 1988-03-08 | Niobium-containing high strength fishing |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN1014080B (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2003056051A1 (en) * | 2001-12-28 | 2003-07-10 | Xizhe Jiang | Yw35 steel and low temperature fishplate made from it |
| CN1302140C (en) * | 2003-10-21 | 2007-02-28 | 酒泉钢铁(集团)有限责任公司 | Micro-alloyed high-carbon steel and application thereof |
| CN101942614A (en) * | 2010-08-26 | 2011-01-12 | 姚圣法 | High-strength special steel and machining method thereof |
| CN101942613A (en) * | 2010-08-26 | 2011-01-12 | 姚圣法 | Method for processing high-strength and ultrahigh-strength shaped steel |
-
1988
- 1988-03-08 CN CN 88101251 patent/CN1014080B/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| CN1035682A (en) | 1989-09-20 |
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