US3519497A - Method for the thermal treatment of steel rails - Google Patents

Method for the thermal treatment of steel rails Download PDF

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Publication number
US3519497A
US3519497A US545936A US54593666A US3519497A US 3519497 A US3519497 A US 3519497A US 545936 A US545936 A US 545936A US 54593666 A US54593666 A US 54593666A US 3519497 A US3519497 A US 3519497A
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Prior art keywords
rail
rails
cooling
steel
bed
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Expired - Lifetime
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US545936A
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English (en)
Inventor
Jacques Pomey
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Lorraine Escaut SA
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Lorraine Escaut SA
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Priority claimed from FR14981A external-priority patent/FR1458157A/fr
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    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/34—Methods of heating
    • C21D1/53—Heating in fluidised beds
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/04—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for rails
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese

Definitions

  • the present invention relates to a method and an installation intended to improve generally the properties of steel rails.
  • the head of the rail passing continuously out of the rolling mill was sprinkled with a moderate quantity of water; after this watering zone, the surface layers were re-heated by the heat diffused throughout the body of the head, which remained hot.
  • the method still has numerous disadvantages.
  • taking account of the high production of rolling mills it is desirable to have available cooling pits of very large capacity, which are bulky and expensive.
  • the operation of loading the rails into the pits is accompanied by deformation of the rails due to the handling necessary, and results in irregular cooling, so that it becomes necessary to straighten the rails.
  • the inherent quality of the steel is very dispersed, so that it is in fact necessary to restrict the content of carbon and manganese in the steel, which does not permit its life to be increased as much as would be desirable.
  • the method in accordance with the invention enables ice k in particular all the defects of the previous techniques to be remedied.
  • the rail while the rail is still hot at the outlet of the rolling mill, it is immersed in a cooling medium maintained at constant temperature, so that the steel undergoes a complete isothermic transformation, perlitic or preferably 'bainitic.
  • the cooling medium is a fluidized bed of refractory pow der maintained at a constant temperature, and the rail is introduced into this bed in such manner that the head of the rail is at the bottom, the flange being uppermost and the flat face of this latter being horizontal, so that the rising flow which ensures the fiuidization of the bed comes first into contact with the head of the rail.
  • the surface of the rail flange which will constitute the lower surface when in use on railway tracks, becomes the horizontal upper surface during the course of the treatment, due to the fact that the rail is turned through at the moment of its immersion while hot in the fluidized powder bed.
  • Another special property of the profile of the rail is that, while the flange represents approximately the same mass as the head of the rail, its surface area is substantially double. Since, with the method according to the invention, the whole surface which has become the upper horizontal face is protected against cooling, the surface area which continues to be cooled is of the same order for the flange and for the head. Since the masses are of the same order of magnitude, the average rate of cooling is substantially the same for the flange and for the head, contrary to that which occurs in natural cooling in air or in a liquid (in which the flange would be cooled approximately twice as fast as the head). The result of the equality of rates of cooling with the method accord ing to the invention is that the rail remains straight during cooling, and that in consequence it is free from internal stresses.
  • the method in accordance with the invention utilizes in some places the good calorific conductivity of fluidized powder media, and at other places the good heat insulation of powder media in a state of rest, this combination of effects being associated with the shape of the profile of the rail and with the orientation given to the said rail.
  • the uniformity of the rate of cooling is furthermore simultaneously related to the ratio of the surface areas and to the ratio of the masses of the flange and the head of the rail.
  • the temperature of the cooling medium and the time for which the rails remain in this medium will of course depend on the composition of the steel and on the temperature of the rails as they pass out of the rolling mill.
  • the temperature could be chosen, in accordance with the foregoing considerations, between 560 and 620 C., with an immersion time corresponding to a temperature-level period of 200 to 800 seconds, the hardness being comprised between 23 and 43 Rockwell Cone, depending on the composition and the treatment.
  • the temperature may be chosen between 380 and 460 C., with an immersion time corresponding to a temperature-level period of 300 to 900 seconds, the Rockwell Cone hardness being comprised between 34 and 44, according to the composition and the treatment.
  • the invention also relates to the rails obtained by the above method, and which have advantageous characteristics as compared with rails manufactured by previous techniques. These characteristics may be considered from various aspects, namely the chemical composition, the structure, the mechanical properties, the external appearance and the properties of use. In fact, the product according to the invention is always distinguished from previous rail steels by at least one of the properties specified above, and in the majority of cases by a number of these simultaneously.
  • the content of the addition elements Mn, Ni, Cr, M0 is extremely limited and these elements can only be added if the carbon content with respect to eutectoid carbon steel is reduced in a corresponding manner, in order to prevent the appearance of the constituents of temper: bainite and martensite in a mixture, during the course of natural cooling on,the grid.
  • martensite is a cause of fragility and increases 4 the risk of formation of flakes. If, on the contrary, the cooling takes place slowly in a pit, the alloy elements have no longer a favourable effect.
  • the rails can take advantage of the full and favourable effect of the addition elements.
  • the rails according to the invention can contain 0.4 to 1% C, 0.5 to 2.5 Mn, 0.02 to 1.8% Si, and they may also contain 0 to 1.5% Cr, 0 to 0.5% Mo, 0 to 0.4% V, 0 to 0.25% Nb, without any resulting disadvantage, and obtaining the benefit of these additions.
  • the structure is uniform throughout the whole mass, and in consequence over the whole of any section, which is not the case with rails which are cooled naturally.
  • the centre of the head which is cooled more slowly has a structure in which the pro-eutectoid elements are definitely separate, and in wich the perlite is coarser, the steel being less hard at its heart than at its surface.
  • the surface layers and in the thinnest parts in which the cooling is more rapid if the steel is fairly well charged with alloy elements, there is a very unfavourable formation of bainite and martensite.
  • the structure in the case of rails treated locally, the structure is naturally heterogenous, and in rails having undergone a tempering operation followed by annealing, the structure is sorbitic, different from bainite in its method of formation, and it is obtained by a more costly process.
  • These products are therefore different from the products according to the invention, in which not only the structure and the hardness are uniform, but also the structure is constituted by pure lower bainite, without any trace of martensite, this bainite being an extremely fine and hard mixture of ferrite and carbides.
  • the rail during the course of the cooling control by the fluidized powder bed, the rail remains straight and is free from residual stresses and internal tensions, whereas in methods employing temper and annealing, the rail is deformed and, after straightening retains large internal stresses which have a detrimental effect.
  • a further characteristic feature of the product according to the invention is that the resistance to shock of the rails is greater than or at least equal to that of tempered and annealed rails, for the same carbon content and the same hardness.
  • the liquid steel has not been treated under vacuum in order to drive-off hydrogen
  • the rail steel is highly alloyed, with the prior technique it exhibits flakes which result in temper shrinkage cracks after treatment, or which result in the formation of fissures during straightening.
  • the steel treated according to the invention does not contain either flakes or temper cracks or straightening fissures. In particular, when carrying out an examination by ultra-sonic tests, no continuity defects are revealed.
  • the steel obtained is more resilient, harder, more enduring against alternating stresses and more resistant to wear;
  • the steel obtained is more resilient, has greater endurance to alternating stresses and is more resistant to wear;
  • the rails obtained are sounder when examined by ultra-sonic tests, have a better resistance to shock and a better resistance to alternating stresses.
  • the invention also extends to cover an installation for carrying the above method into effect.
  • An installation according to the invention will comprise more precisely handling means capable of lifting the rail at numerous points at the outlet of the rolling mill and of turning it on its own axis, preferably parallel to the rolling axis, so that the head of the rail is at the bottom, the flange being at the top with its flat face substantially horizontal, a receptacle fitted with a lower grating and containing the powdered refractory bed capable of being fluidized by a flow of air or of any other suitable gas discharged through the lower grating by means of a windbox, means for ensuring a constant temperature of the fluidized bed, and lifting means for extracting the rail from the fluidized bed so as to bring it into a subsequent cooling area.
  • the means for ensuring a constant temperature of the bed may comprise heating means and cooling means, a temperature regulator actuated by a thermometer probe and a servo-mechanism acting on the said heating and cooling means.
  • the heating means may utilize the Joule effect, combustion, etc., but a re-heating can also be effected by means of the fluidization gas itself.
  • these may work by air circulation, by means of mist or water, etc., an injection of atomized water into the fluidization gas being also capable of use for this purpose.
  • An installation of this kind having a small overall size can be interposed on the cooling area of a high production rolling mill. In any case, for the same rate of production, it necessitates less room than cooling pits. It may of course be wholly mechanized and made automatic by bringing into play conventional techniques of handling, automation and regulation.
  • FIG. 1 is a diagrammatic view with cross-section of an installation according to the invention
  • FIG. 2 shows the position of a rail in the fluidized powder bed
  • FIG. 3 is an alternative form of FIG. 1, for the case in which the cooling time of the rail in an isothermal manner is greater than the production rate of the rolling mill;
  • FIG. 4 is substantially similar to FIG. 1, and shows in addition the combination of a fluidized bed ensuring rapid cooling and homogenization of the rail with a furnace ensuring the isothermal transformation and the maintenance of the rail at a constant temperature;
  • FIG. 5 is an alternative form of the device of FIG. 3, with two wind-boxes.
  • FIG. 1 is a transverse section of the installation, in which the development in length normal to the plane of the drawing corresponds to the length of the longest rails to be manufactured.
  • the mechanical handling devices have not been shown, since they may be of very varied types and their provision presents no difllculties for those skilled in the art.
  • a roller track located at the output side of a rolling mill.
  • a hot straight rail A which is located on the track 1, or which has been slid laterally in order to be freed from the rolling mill, is gripped at a large number of points in order to avoid any deformation due to the effect of its weight and is lifted at B by lifting means. It is then turned over at C and brought above a fluidized bed at D. It is in this position, with the head of the rail downwards and the flat face of the flange arranged horizontally that the rail is introduced into the fluidized bed, in which it is immersed as indicated at E.
  • the fluidized refractory powder bed prepared in a manner well known per se, is contained in a receptacle 2 which comprises at its lower portion a horizontal grating 3 designed in such manner that the grains of the bed cannot pass through the openings of the said grating.
  • the receptacle 2 is extended below the grating by a wind-box 4, into which a fan 5 blows air (or any other suitable gas), the air or gas being cold or heated as may be necessary.
  • the rate of flow of this gas is of course kept within the limits essential to ensure the fluidization of the medium.
  • heating means 6 may utilize the Joule effect or combustion
  • cooling means 7 may be constituted by a circulation of air, of mist or of water.
  • the heating may be ensured by the fluidization gas itself, brought-up to a suitable temperature and the cooling may be effected by injection of water sprayed into the fluidization gas.
  • thermometer probe 8 which can be of the expansion, contact electromotive force, or resistance type, etc.
  • the rail immersed at E is cooled and the steel is transformed isothermally, since the temperature of the medium is maintained constant. After cooling to the temperature of the medium, and after complete isothermal transformation of the steel, the rail is removed from the bath into the position shown at F. It can then be shifted laterally to G and laid down at H on the final cooling area 9.
  • the rail is immersed from the position D to the position E and then is displaced laterally in the powder bath from E to E.
  • the rail is then removed from the bath from the position E to the position F, and is then moved sideways at G and laid down at H on a cooling grid 9,
  • the heating and cooling elements may be immersed in the bath, either below the level of the rails if the lateral moving device is located above in free air, or above in the contrary case.
  • These elements 10 may for example be arranged in tubes parallel to each other, located longitudinally or transversely with respect to the length of the tank. Additional cooling tubes may also be arranged lengthwise on the input side, below the position E of the rails and the adjacent positions, at which it is necessary to extract heat so as to cool the rails to the desired temperature, and not to provide cooling tubes in the remainder of the bath in which the rail is kept at a constant temperature and in which, on the contrary, the losses of heat must be compen-sated.
  • the rail may also be left in the fluidized bath for just the time necessary for its cooling to the desired temperature and the homogenization of the temperature, after which it is extracted from this medium and is passed into a complementary device at which it is maintained at a constant temperature for the time necessary to complete the isothermal transformation.
  • FIG. 4 An alternative arrangement of this kind is shown in FIG. 4, in which there is again seen, on the left-hand side, an installation similar to that of FIG. 1. This installation is followed, for example, by a pusher furnace 11 or a pusherstove, in which the rails travel up to the outlet position J, the rails then passing on to the grid 9 for final cooling in free air.
  • FIG. 5 shows an alternative form of FIG. 3, in which two wind-boxes 12 and 13 are provided instead of a single wind-box.
  • the first box 12 is located on the side at which the hot rails arrive to be cooled rapidly, and it is supplied with air or cold gas delivered by a fan 14.
  • the second wind-box 13 receives hot gases at the actual temperature of stabilization of the rails and of isothermal transformation of the steel.
  • cooling tubes 15 may be provided, immersed in the fluidized bed on the incoming side of the rails.
  • the hot gases may be supplied to the front box 13 from any suitable source.
  • they may be obtained from a fan 16 and pass into a heating chamber 17, kept at the desired temperature by a burner 18, with mixture of combustion gases and regulation of the temperature by means of a pyrometer probe 19.
  • the controlled cooling device according to the invention for a high production rolling mill, occupies relatively little space and that it can be arranged in a cooling bay between the roller track at the outlet of the rolling mill and the natural cooling grid in free air.
  • the succession of the various operations can be carried out in a wholly automatic manner, without causing any special difficulty for persons skilled in the art.
  • a method of heat treatment for improving the properties of steel rails comprising the steps of providing a fluidized refractory powder bed, maintaining the bed at a constant temperature between 560 and 620 C., taking a hot rail as it leaves a rolling mill and immersing the rail completely in the bed; the immersion time corresponding to a stationary-temperature period of 200 to 800 seconds, whereby a complete and uniform perlitic transformation is achieved, the rail being oriented within the bed with its head at the bottom, its flange at the top, and the flat face of the flange horizontal, so that the gas flowing upwardly to fluidize the bed first encounters the head of the rail, and operating the bed so that it stagnates directly above the horizontal flange face and the powder particles come to rest upon and cover said face to insulate it, whereby said rail top and rail flange cool at substantially the same rate despite the greater surface area of the flange.
  • a method of heat treatment for improving the properties of steel rails comprising the steps of providing a fluidized refractory powder bed, maintaining the bed at a constant temperature between 380 and 460 C., taking a hot rail as it leaves a rolling mill and immersing the rail completely in the bed; the immersion time corresponding to a stationary-temperature period of 300 to 900 seconds, whereby a complete and uniform bainitic transformation is achieved, the rail being oriented within the bed with its head at.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Heat Treatment Of Articles (AREA)
  • Metal Rolling (AREA)
US545936A 1965-04-28 1966-04-28 Method for the thermal treatment of steel rails Expired - Lifetime US3519497A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR14981A FR1458157A (fr) 1965-04-28 1965-04-28 Procédé et installation de traitement thermique des rails
FR53062A FR90024E (fr) 1965-04-28 1966-03-11 Procédé et installation de traitement thermique des rails

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US3519497A true US3519497A (en) 1970-07-07

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US (1) US3519497A (sv)
AT (1) AT287038B (sv)
BE (1) BE680222A (sv)
DE (1) DE1533982B1 (sv)
ES (1) ES326499A1 (sv)
FI (1) FI46521C (sv)
FR (1) FR90024E (sv)
GB (1) GB1131662A (sv)
LU (1) LU50979A1 (sv)
NL (1) NL6605705A (sv)
OA (1) OA01952A (sv)
PL (1) PL72550B1 (sv)
SE (1) SE309257B (sv)

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4082577A (en) * 1974-08-16 1978-04-04 Fried. Krupp Huttenwerke Ag Process for the heat treatment of steel
US4170494A (en) * 1976-06-07 1979-10-09 Kobe Steel, Ltd. Surface treatment for metal according to fluidized bed system
WO1981002585A1 (en) * 1980-03-13 1981-09-17 P Strandell Arrangement for cooling metal workpieces
US4375995A (en) * 1978-05-12 1983-03-08 Nippon Steel Corporation Method for manufacturing high strength rail of excellent weldability
US4486248A (en) * 1982-08-05 1984-12-04 The Algoma Steel Corporation Limited Method for the production of improved railway rails by accelerated cooling in line with the production rolling mill
WO2001011096A1 (en) * 1999-08-04 2001-02-15 Qinetiq Limited Improved bainitic steel
CN103468906A (zh) * 2013-09-17 2013-12-25 北京科技大学 一种低温温轧制备2000MPa级纳米尺度贝氏体钢工艺
US9074817B2 (en) 2011-12-13 2015-07-07 Rolls-Royce Plc Fluidised bed treatment
US9182174B2 (en) 2011-12-13 2015-11-10 Rolls-Royce Plc Fluidised bed treatment
CN113416818A (zh) * 2021-05-12 2021-09-21 包头钢铁（集团）有限责任公司 一种高强韧性贝马复相贝氏体钢轨的热处理工艺

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3666253A (en) * 1969-12-26 1972-05-30 Yuri Yoshio Fluidized bed furnace
BE884443A (fr) * 1980-07-23 1981-01-23 Centre Rech Metallurgique Perfectionnements aux procedes de fabrication de rails a haute resistance
US4895605A (en) * 1988-08-19 1990-01-23 Algoma Steel Corporation Method for the manufacture of hardened railroad rails
GB2297094B (en) * 1995-01-20 1998-09-23 British Steel Plc Improvements in and relating to Carbide-Free Bainitic Steels
AT407057B (de) * 1996-12-19 2000-12-27 Voest Alpine Schienen Gmbh Profiliertes walzgut und verfahren zu dessen herstellung
DE102011014877A1 (de) * 2011-03-23 2012-09-27 Db Netz Ag Verfahren zum Umschmieden eines Gleisteils und gemäß diesem Verfahren umgeschmidete Gleisteile
AT512792B1 (de) 2012-09-11 2013-11-15 Voestalpine Schienen Gmbh Verfahren zur Herstellung von bainitischen Schienenstählen

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US368132A (en) * 1887-08-09 coffin
US879634A (en) * 1907-07-12 1908-02-18 Robert Abbott Hadfield Method of improving steel rails.
US1827616A (en) * 1928-09-29 1931-10-13 Firm Of Messrs Sandberg Manufacture of railway and tramway rails
US2116070A (en) * 1936-01-27 1938-05-03 American Brake Shoe & Foundry Heat treatment of ferrous sections
US2576223A (en) * 1948-02-17 1951-11-27 Hofmann Fritz Method of producing wear resistant steel rails
US3053704A (en) * 1953-11-27 1962-09-11 Exxon Research Engineering Co Heat treating metals
US3197346A (en) * 1953-11-27 1965-07-27 Exxon Research Engineering Co Heat treatment of ferrous metals with fluidized particles

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE612757C (de) * 1928-09-29 1935-05-04 Christer Peter Sandberg Verfahren zur Verhuetung von inneren Rissen beim Kuehlen von Eisenbahn- und Strassenbahnschienen

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US368132A (en) * 1887-08-09 coffin
US879634A (en) * 1907-07-12 1908-02-18 Robert Abbott Hadfield Method of improving steel rails.
US1827616A (en) * 1928-09-29 1931-10-13 Firm Of Messrs Sandberg Manufacture of railway and tramway rails
US2116070A (en) * 1936-01-27 1938-05-03 American Brake Shoe & Foundry Heat treatment of ferrous sections
US2576223A (en) * 1948-02-17 1951-11-27 Hofmann Fritz Method of producing wear resistant steel rails
US3053704A (en) * 1953-11-27 1962-09-11 Exxon Research Engineering Co Heat treating metals
US3197346A (en) * 1953-11-27 1965-07-27 Exxon Research Engineering Co Heat treatment of ferrous metals with fluidized particles

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4082577A (en) * 1974-08-16 1978-04-04 Fried. Krupp Huttenwerke Ag Process for the heat treatment of steel
US4170494A (en) * 1976-06-07 1979-10-09 Kobe Steel, Ltd. Surface treatment for metal according to fluidized bed system
US4375995A (en) * 1978-05-12 1983-03-08 Nippon Steel Corporation Method for manufacturing high strength rail of excellent weldability
US4426236A (en) 1978-05-12 1984-01-17 Nippon Steel Corporation Method for manufacturing high strength rail of excellent weldability
WO1981002585A1 (en) * 1980-03-13 1981-09-17 P Strandell Arrangement for cooling metal workpieces
US4486248A (en) * 1982-08-05 1984-12-04 The Algoma Steel Corporation Limited Method for the production of improved railway rails by accelerated cooling in line with the production rolling mill
WO2001011096A1 (en) * 1999-08-04 2001-02-15 Qinetiq Limited Improved bainitic steel
US6884306B1 (en) * 1999-08-04 2005-04-26 Qinetiq Limited Baintic steel
US9074817B2 (en) 2011-12-13 2015-07-07 Rolls-Royce Plc Fluidised bed treatment
US9182174B2 (en) 2011-12-13 2015-11-10 Rolls-Royce Plc Fluidised bed treatment
CN103468906A (zh) * 2013-09-17 2013-12-25 北京科技大学 一种低温温轧制备2000MPa级纳米尺度贝氏体钢工艺
CN113416818A (zh) * 2021-05-12 2021-09-21 包头钢铁（集团）有限责任公司 一种高强韧性贝马复相贝氏体钢轨的热处理工艺
CN113416818B (zh) * 2021-05-12 2022-09-23 包头钢铁（集团）有限责任公司 一种高强韧性贝马复相贝氏体钢轨的热处理工艺

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Publication number Publication date
DE1533982B1 (de) 1970-11-26
PL72550B1 (sv) 1974-08-30
NL6605705A (sv) 1966-10-31
SE309257B (sv) 1969-03-17
OA01952A (fr) 1970-02-04
AT287038B (de) 1971-01-11
LU50979A1 (sv) 1966-06-27
GB1131662A (en) 1968-10-23
ES326499A1 (es) 1967-03-01
FI46521C (sv) 1973-04-10
FI46521B (fi) 1973-01-02
BE680222A (sv) 1966-10-03
FR90024E (fr) 1967-09-29

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