DE2113418A1 - Steel rail - Google Patents

Description

PATENT LAWYERS

DIPL.-ING. GONTHER KOCH DR.TINO HAIBACH 17 10 /

8 MÜNCHEN 2, f 9, 'Mäfl \\ £

BRITISH STEEL CORPORATION, London, S.W.1 - England

and

BRITISH RAILWAYS BOARD, London, U.W. 1 - England

Steel rail

The invention relates to steel and more particularly relates to rail steel and profiled steel made therefrom Rails.

Up to now, steel for rails has primarily been produced with a carbon content of about 0.5 % and a Mcngangeho.lt of about 1.0>&. After rolling, the rails are usually straightened and cut to the desired length before being used. A typical example of such rails are those described in the following standard sheets:

British Form 11: 1959 "Plat Bottom Hailway a'.ails "(flat-footed railroad tracks). Union Internationale des Chemins de i'ers U. 1.0. 860-0 "Technical Specification for the Supply of Vigriole (Plat Bottom) Hails in Non-Treated Steel "(Technical delivery specification for Vignol rails (! '' Ir.eher puss) made of untreated steel). American Hailv / ay Engineering Association, Manual of Hecommended Practice, chap. ^, Rails, Part 2, Specification I960.

ORIGINAL

109841/1293

The ones delivered in accordance with the above standards Rails have adequate tensile strength (usually at least 69 kg / mm) and sufficient wear resistance. However, the structure of the steel is ordinary a coarse-grained, essentially pearlitic structure of very low impact strength, in which the impact strength normally at room temperature is less than 1.59 mkg, if after the method of Oharpy using a 2mm V-shaped specimen Notch is measured. The steel usually has an initial austenitic grain size of A.S.T, M. 3 and "has a ferrite grain size of about A.S.T.M. 4 Operating conditions can occur due to brittleness of fractures that are relatively small Show imperfections that may have developed during operation, e.g. B. based on fatigue cracks, which can arise at bolt holes running through the rail web; furthermore, such breaks can be caused by hoisting and other errors within the rail.

The invention now provides a rail section of steel in front, a grain refining element, and preferential ^, also a hardening; contains e lernent, and either normalizing or a controlled rolling process of the type described below has been subjected, to produce a fine-grained structure wherein the type and amount of grain refining element in the steel and the grain refining process to which the steel is subjected are such as to obtain a ferrite grain size finer than ASTM 8 and preferably finer than ASTM 9.

In the following the expression "normalize" a heat treatment process in which the steel is re-exposed is heated to a temperature that is above its upper

109841/1? 93

table point, whereupon the steel is cooled in air. The upper critical point can be at a typical Steel at around 850 ° C. The term "regulated Rolling "refers to a rolling process in the following, which the steel is normally at a temperature of about 1000 ° C is finished, down to temperatures in Range from 700 to 900 ° G is rolled.

The refining element can be one or more of aluminum, niobium, vanadium, titanium and zirconium; These substances are preferably used in the following amounts, based on the total weight of the material: 0.015 to 0.1 % aluminum, 0.01 to 0.1 % niobium or 0.05 to 0.2% vanadium.

Suitable hardening elements include silicon, manganese, chromium, nickel and / or molybdenum. Based on the total weight of the steel, these substances are preferably used in the following amounts: 0.05 to 1.5 % silicon, 0.25 to 1.5 % chromium and 0.5 to 2.5% manganese.

Based on the total weight of the steel, nitrogen is usually present in an amount between 0.005 and 0.030 % , with the maximum being preferably 0.025 % .

The standard currently manufactured Rail steel usually has an initial austenitic grain size of about A.S.T.M. 3 or a ferrite grain size from about A.SeTsM. 4. If the invention is applied using grain attenuation elements and a Normalization process or regulated rolling is carried out it is possible to achieve an initial austenitic Kan size that is finer than A.S.T.M. 6, and a ferrite grain size finer than A.S.T.M. 8. The use of grain refinement elements in combination normalizing heat treatment can result in a ferrite grain size finer than A.S.T.Fi 10 or

109841/1793

even finer than A »SQ? _O M. 12 is.

With the help of the invention it is possible to produce an improved steel, which compared to the known Rail steel down to temperatures of ζο B. -15 ° C considerably more resistant to brittleness fractures and at the same time still has sufficient tensile strength and sufficient yield strength, and which, especially when using the hardening elements, maintains its wear resistance, which is the case with rail steels is of particular importance.

ψ According to the invention, it has been shown that this

improved resistance to brittleness fracture resulting from an improvement in notched impact strength can be read, can be achieved if one uses the mentioned grain refining elements in the steel and at the same time carries out either a normalization heat treatment or a regulated rolling process.

Based on the total weight of steel, a steel rail made in accordance with the invention includes the following Substances:

Carbon: 0.2 to 0.85 %

Sulfur: 0.06 J »(maximum)

W phosphorus: 0.06 % (maximum)

The steel also contains at least one of the following hardening elements in the specified length:

Manganese: 0.5 to 2.5 #

Silicon: 0 to 1.5 %

Chromium: 0 to 1.5 %

Nickel: 0 to 1.0 %

Molybdenum: 0 to 0.6 #,

provided that a total content of hardening elements of 5 percent by weight is not exceeded, as well as at least one of the following grain refining elements in

109841/1793

the specified length:

Aluminum: 0.015 "to 0.1 % Vanadium: 0.05 to $ 0.2

Niobium: 0.01 to 0.1 %

Titanium: 0.15 to 0.3 %

Zircon: 0.15-0.3 #

together with nitrogen in an amount between 0.003 and 0.30 ^c / o and in an essentially stoichiometric ratio to the amount of grain refining elements, the remainder being iron and incidental impurities; Here the rail steel profile has either been subjected to a leveling treatment or a regulated rolling process of the type still to be described in order to achieve a ferrite grain size that is finer than ASTM

In a preferred embodiment of the invention, the aforementioned rail steel has a carbon content of 0.2 to 0.6 y6 , the concentration element is aluminum, vanadium and / or niobium, and the ferrite grain structure is finer as A. &. TM 9.

A otahlschienenprofil, that of the one given above Definition corresponds, and in which it is within the framework of the invention to a modification of one for producing rail profiles of suitable steel according to the current delivery regulations applicable to rails, ζ. Β. according to the British Standard 11: 1959, htnuelt, has the following composition:

Carbon: 0.4 to 0.6 # Manganese: 0.95 to 1.25 %

Sulfur: 0.06 % (maximum)

Phosphorus: 0.06 % (maximum) Nitrogen: 0.003 to 0.030 % Silicon: 0.08 to 0.20 %

BATH ORIGINAL / 1 5Qr?

and

Aluminum: 0.015 to 0.1 % or vanadium: 0.05 to 0.2% or

Niobium: 0.01 to 0.1 JSi.

! In the absence of vanadium in the above composition can combine the content of aluminum and niobium so that an aluminum content of 0.015 to 0.10 ° / o and a niobium content of 0.01 to 0.10% results; in this case the rail material is preferably rolled in a controlled manner.

These rails, in which grain refining elements are added to a base alloy, the ones after is similar to British Standard Sheet 11: 1959, and which are normalized or rolled into a regulated manner have a good notched impact strength and high resistance to brittleness fractures. However, the impact strength becomes in the particularly preferred embodiments of the invention improved in that a lower Carbon content of the alloy is provided, the z. B. in the range of 0.28 to 0.39 percent by weight.

Such rails can, based on the total weight of the steel, the following materials in the specified Quantities contain:

Carbon: 0.28 to 0.39 % Manganese: 1.2 to 1.6 $

Sulfur: 0.06 fo (maximum)

Phosphorus: 0.06 # (maximum) Nitrogen: 0.003 to 0.030 f & Silicon: 0.035 % (maximum)

and

Aluminum: 0.015 to 0.10 fr or vanadium: 0.05 to 0.20 #

The most preferred types of this steel contain from 0.02 to 0.06 percent aluminum or from 0.10 percent by weight

109841/1293

0.15 $ vanadium and O ₁ OO to Op.5 % nitrogen, whereby the rails made from it have been normalized, or alternatively 0.015 to 0.10 % aluminum and additionally 0.01 to 0.1 $ niobium, these rails on have been rolled in a regular manner.

The manufacture of splints with a fine-grained Structure leads to an increase, particularly if a low pearlite content is ensured the resistance to cracks in brittleness. The reduction in the pearlite content and the increase in the Ferrite content is reduced by using a Carbon content achieved. However, this measure is in some cases accompanied by a decrease in strength and wear resistance. With the particularly preferred However, embodiments of the invention allow the tensile strength and wear resistance in To improve this case by the fact that the increased proportion of the ferrite phase is reinforced, namely by a Solution hardening in the solid state by adding a hardening element such as silicon, manganese, chromium, nickel or Molybdenum or combinations of these substances.

Thus, in its most preferred embodiment, the invention provides a profiled rail, which according to FIG the above data 0.28 to 0.39 percent by weight carbon and as a hardening element 1.2 to 2.5 percent by weight Contains manganese and / or 0.8 to 1.2 percent by weight silicon. The hardening elements, manganese, silicon, chromium, Nickel and molybdenum can be used in a more general manner within the aforementioned amount ranges will. The preferred grain refining elements are aluminum and vanadium are used, the rails were normalized; alternatively, aluminum and niobium are used together, whereby the rails are rolled in a controlled manner in this case.

109841/1793

The invention and advantageous details of the invention are explained in more detail below on the basis of exemplary embodiments.

A steel coming out of a furnace that, based on total weight, contains 0.2-0.85 # carbon, 0.5 % manganese (minimum), 0.06 % phosphorus (maximum), 0.06 % sulfur (maximum), and 0.003% contains up to 0.025 % nitrogen, the remainder of incidental impurities consisting of iron, is delivered to a pan in which the grain refining element is added to the steel. The temperature of the melt is generally about 1600 ° G. At this stage, the hardening element can also be added to the melt.

The melt can then be poured into a block mold with the help of the ladle, and after it has solidified, the Steel can be subjected to one of the two rolling processes described below to produce profiled rails.

In the first method, the billet is heated to around 1300 ° C before it is fed to a billet rolling mill will. The roughed billet coming from the roughing mill

is then rolled at a temperature of about 950 to IO5O ⁰ C. In the present case, the rolled rail can have been produced from the block dii ^ ect, ie without reheating; Alternatively, the block may have been reheated ⁰ 0 after rough rolling to a temperature up to IJOO. The rolled bar is cooled to a temperature below about 700 ° 0 and then normalized, i.e. it is reheated to a temperature of the order of 850 C in order to refine the grain and to give rise to precipitation products which restrict grain growth, after which the splint is cooled in air.

109841/1793

In the second method, the ingot or the pre-rolled block a.uf at least 700 ° C, and preferably cooled to 500 ° C and then again to a temperature between 1250 ° and IO5O G, ie, a temperature of the order of II5O ⁰ C, brought, and the rolling process is continued, so that a temperature in the range of 700 to 9OÜ C results during finishing (controlled rolling). The low reheating temperature used in this process leads to the presence of grain refiners during the actual rolling process, and these otoffe lead to the creation of a fine structure that is similar to the structure that is created during normalization.

The method just described can be modified in various ways. For example need the alloy additives not to be added to the melt in the ladle. These additives could be in the otahlschmelschofen be introduced, and in some cases additives are added to the steel in the furnace, in the pan and in the block form. Furthermore, it is not necessarily It is necessary to pour the melt contained in the ladle into the block mold, but the melt can be made before rolling can be processed by a continuous caster or other processes can be used to produce blocks.

In order to facilitate understanding of the invention, are in the following exemplary embodiments in tabular form. Table I gives the chemical composition and the grain size, while the final mechanical properties can be seen from Table II are.

I) ;: s Example 1 is typical of rail steels of the type currently being produced, e.g. B. correspond to the British standard 11: 19i> 9. This example is only about

BAD ör; gikal

109811/1793

- ίο -

Listed for comparison purposes, d. i.e., it does not serve to to illustrate the invention. The low impact strength values achieved with this steel are to be compared with the corresponding results that apply to the other examples, which of the Invention correspond.

Examples 2 to 10 apply to steel railroad tracks produced according to the invention. In all cases the steel had an sulfur and phosphorus content of less than 0.06 % and the perite grain size was finer than ASTM 8.

Examples 2, 3 and 4 are typical of the results which are achieved when a normal quality rail steel, e.g. B. according to the British standard sheet 11: 1959 »Add grain refiners and then normalize the rolled rails.

Examples? .2A and 2B illustrate the use of aluminum, while Example 3 is vanadium and in the example 4 · niobium was added.

Examples 5, 6, 7 and 8 leave the high notched impact strength realize that is achieved by having a lower carbon content and a higher manganese content in conjunction with grain refinement elements, and if the rolled rails are subsequently normalized. Examples 5 and 6 illustrate the use aluminum as a grain refining element, while Examples 7 and 8 illustrate the use of vanadium. Examples 6 and 8 also show that a higher silicon content of the steel leads to an improvement in the Wear resistance leads.

109841/1793

- li -

Examples 9 and 10 illustrate the effect of using aluminum together with niobium as grain refinement elements, for the pail that the rails are rolled in a regulated manner. In the example 9 corresponds the composition of that of the rail steel in use up to now, but with the grain refining elements were added, while the composition in Example 10 is the preferred composition of a steel with lower carbon content and higher slope content.

109841/179?

Table I.

Chemical composition grain size

game - ; Änfängl. ¥ ev-

G i » Mn fo Si Io Y fo Al f» Ή fo Wo fo Ko ^ gr ^ K ^ Gr.

ASTM 'ASTM'

1 A.
B.
W. 0.45
0.50
0.59 1.15
1.20
1.12 0.13
0.12
0.11 - 0.005 0.016 -
0.006 -
0.005 - 4th
3
3 14th 2 A.
B. 0.46
0.55 1.20
1.12 0.22
0.13 - 0.057
- '0.062 0.017 -
0.006 - 8th
7th 3 0.45 1.10 0.20 0.16 0.011 - 10 4th 0.45 1, 18 0.24 - - 0.016 0.048 6th 5 0.39 1.40 0.21 - 0.045 0.017 - 10

6 A 0.34 1.38 0.20 - 0.042 0.010 8 12

B 0.36 1.32 0.50 - 0.052 0.014 9 13

C 0.40 1.46 0.98-0.038 0.013-7 10

0.35 1.43 0.21 0.15 - 0.009 - 10 14

8 A 0.30 1.47 1.28 0.14 B 0.33 1.31 0.90 0.10 0 0.36 1.43 1.00 0.19

0.46 1.15 0.17 - 0.045 0.016 0.048 7 10

10 0.36 1.47 0.33 - 0.061 0.014 0.050 7

0.011 - 9 13th 0.020 - 10 14th 0.022 - 9 12th

109841 / 179- *

table II
.Strength properties.

Example Lower Fraction ^ ene Fraction ^A ~

Ur. Yield strength ^ ^cn limit ^ g ^ - lacing

kg / mm kg / mm

1 A. 43.2 81.0 21.0 B. 42.2 78.7 22.0 C. 46.0 79.1 18.0

_U 5

2 A.
B. 41.3
43.2 69.9
81.3 27.5
20.0 59.6
36.8 3 47.4 71.7 22.2 62.4 4th 42.1 72.3 23.8 43.2 5 47.2 71.2 32.0 62.8

6th A. 47.2 70.9 32.0 62.0 B. 47.2 72.4 28.0 57.0 C. 50.4 80.0 26.0 51.2

49.8 W, 3.28.3 67.2

8th A. 55.1 73.4 31.0 57.2 B. 53.2 73.7 28.0 48.4 0 59.8 78.7 29.0 53.6

39.4 69.3 26.0 52.5

39.1 65.8 33.0 56.7

109841/1293

Table II
(Cont.)

Example * Charpy fillet sample

No. At -15 ° 0 Isothermal transition temperature

mkg in ⁰ G at 2.76 mkg

1 - 2 A. 0.4 +120 B. 0.4 +150 5 0 0.5 +120 4th A. 1 Λ - 5th 5 B. 1.4 + 40 6th 3.0 - 20th 0.3 +85 5.9 - 56 7th A. 4.7 - 42 B. 4.0 - 40 C. 2.2 + 6 5.0 - 60

8 A ■ 5.2 - 28

^w B 5.2 - 50

C 2.8-15

1.7 + 15

10 5.2 - 25

Expectations; 109841/1293

Claims (12)

Expectations 1. steel rail, characterized in that it contains a grain refining element and according to the given definition either normalized or subjected to a controlled rolling process to a fine-grained To generate the structure, the type and the amount of the Ivornvei'feinerungselement in the steel and the grain refinement process, to which the steel has been subjected, are such that the steel has an errit grain size which is finer than A.S.T.M. 8th. 2. Steel rail according to claim 1, characterized in that the steel contains at least one grain refining element which, based on the total weight of the steel, is 0.015 to 0.1 % aluminum, 0.01 to 0.1 % niobium 0.05-0.2 % vanadium, 0.015-0.3 % titanium, and 0.015-0.0 % zirconium. 3 · Steel rail according to claim 1 or 2, characterized in that τ indicates that the rail is one as well Contains hardening element. 4. Steel rail according to claim 3, characterized in that the steel contains at least one hardening element, which is based on the total weight of the steel by 0.5 to 2.5 % manganese, up to 1.5 % silicon, up to 1 , 5 # chromium, up to 1.0 % nickel and up to 0.6 % molybdenum. 5. Steel rail, characterized in that the rail is based on the total weight of the steel contains the following substances in the specified quantities: 109841/1293 - Ib - Carbon: 0.2 to 0.85 ¥> Sulfur: 0.06 % (maximum) Phosphorus: 0.06 % (maximum, at least one of the following hardening elements in the specified amounts: Manganese: 0.5 to 2.5 % Silicon: 0 to 1.5 % Chromium: 0 to 1.5 % Nickel: 0 to 1.0 % Molybdenum: 0 to 0.6 #, provided that the total content of hardening elements does not exceed 5 ° / ° , furthermore at least one of the following grain refinement elements in the specified amounts: Aluminum: 0.015 to 0.1 % Vanadium: 0.05 to 0.2 % Niobium: 0.01 to 0.1 % Titanium:. 0.015 to 0 »3 # Zircon: 0.15 to 0.3 % together with nitrogen in an amount between 0.003 and. 0.030 % and in a substantially stoichiometric proportion to the amount of grain refining elements, the remainder being iron and incidental impurities, and that the steel rail has either been subjected to normalization as defined or to a controlled rolling process in order to produce a ferrite grain structure which is finer than ASTM 8. 6. Steel rail according to claim 5 »thereby g e k e η η sign nt that the rail, based on the total weight of the steel, the elements specified below contains in the stated quantities: Carbon: 0.4-0.6 % Manganese: 0.95-1.25 ^ Sulfur: 0.06 % (maximum) Phosphorus: 0.06 % (maximum) 109841/1293 Nitrogen: 0.003 to 0.030 % silicon: 0.08 to 0.20 % and as the grain refining element, 0.015 to 0.1 % aluminum, 0.05 to 0.2 % vanadium, or 0.01 to 0.1 % niobium with the remainder being iron and incidental impurities. 7 · Steel rail according to claim 5 »characterized in that the rail, based on the total weight of steel, which contains the following elements in the specified quantities: Carbon: 0.4 to 0.6 # Manganese: 0.95 to 1.25 % Sulfur: 0.06% (maximum) of phosphorus: 0.06% (maximum) Nitrogen: $ 0.00 to $ 0.030 Silicon: 0.08 to 0.20% aluminum 0.015 to 0.10% of niobium: 0.01 up to 0.10 %, where the best consists of iron and incidental impurities, and that the steel is a regulated rolling process has been subjected. 8. Steel rail according to claim 5 »characterized in that the steel, based on its total weight, contains carbon in an amount of 0.28 to 0.39 % . 9. Steel rail according to claim 8, characterized in that the steel as hardening elements 1.2 to 1.6 percent by weight manganese and up to 0.035 percent by weight silicon and as a grain refining element 0.015 to 0.10 percent by weight aluminum or 0.05 to 0, Contains 20 % vanadium. 10. steel rail according to claim 8, characterized in that the steel hardening elements than 1.2 bit 1.6 weight percent manganese and up to 0.35 weight percent silicon, and as koi nverfeinerungs elements 0.015 109841/1293 to 0.10 weight percent aluminum along with 0.01 Ms Contains 0.1 percent by weight niobium, and that the rail has been subjected to a regulated rolling process « 11. Steel rail according to claim 8, characterized in that the steel as the hardening element 1.2 contains up to 2.5 percent by weight manganese or 0.8 to 1.2 percent by weight silicon. 12. steel rail according to claim 11, characterized ge κ e η η zei seframe that the steel contains as a grain refining element aluminum or vanadium and the steel has been normalized. 13 · Steel rail according to claim 11, characterized in that the steel is used as grain refining elements Contains aluminum together with niobium, and the ötahlprofil rolled in a controlled manner. 109841/1293