`
`1452450
`
`PATENT SPECIFICATION
`
`(22) Filed 19 May 1975
`(21) Application No. 21298/75
`(31) Convention Application No. 2 425 187
`(32) Filed 24 May 1974 in
`(33) Germany (DT) 7
`(44) Complete Specification published 13 Oct. 1976
`(51) INT CL2 C22C 38/38 *
`
`(52) Index at acceptance
`C7A 770 771 782‘A249 A25Y A272 A279 A28X A28Y A30Y
`A316 A319 A320 A323 A326 A329 A339 A33Y A341
`A343 A345 A347 A349 A369 A37Y A381 A383 A385
`A387 A389 A39Y A400 A402 A404 A406 A409 A439
`A44Y A451 A453 A455 A457 A459 A48Y A505
`A507 A509 A51Y A523 A525 A527 A529 A53Y
`/ A541 A543 A545 A547 A55Y A562 A565 A568 A571
`A574 A577 A579 A57Y A584 A587 A58Y A605
`A607 A60Y A619 A61Y A621 A623 A62X A671
`A673 A675 A677 A679 A67X A681 A683 A685 A687
`A689 A68X A693 A695 A697 A699 A69X A70X
`
`(54) RAIL WHEEL
`
`FRIED KRUPP HUTTENWERKE AKTIENGESELL-
`We,
`(71)
`SCHAFT, a German Company of 463 Bochum, Germany, do hereby declare the
`invention for which we pray that a patent may be granted to us, and the method by
`which it is to be performed to be particularly described in and by the following
`statement:—
`' The invention relates to a rail wheel with wheel rim, wheel disc and wheel
`hub
`'
`'
`
`Rail wheels are predominantly produced from unalloyed carbon steels. They
`are used in the naturally hard, normalised heat-treated and wheel-tread-heat—
`treated state. The rail wheel as a solid wheel can consist of one and the same steel
`or, in the form of a composite material, it may have a high-carbon material at the
`periphery (wheel rim) and a softer carbon steel in the interior (wheel disc and
`wheel hub). Such a composite rail wheel is for example described in US. Patent
`Specification 1,149,267.
`The high carbon wheel rim has a structure of more or less finely laminated
`pearlite. This structure and the chemical composition of the wheel rim impair the
`tenacity of the steel. To this is added the fact that when abrasion occurs by block
`braking or by slipping and sliding and martensite is formed because of the high
`carbon content, high martensite hardnesses are attained which can lead to an
`acute danger of cracking. In order to raise the tenacity in the wheel rim, or in the
`whole rail wheel, alloyed steels have been used. With these alloyed steels a heat
`treated structure is developed in order to attain high tenacities by a heat treatment
`consisting of hardening and tempering. Even if a bainitic structure is produced by
`carefully adjusting the analysis and taking into account the given shape of the rail
`wheel and this is tempered in order to improve its tenacity properties,
`the
`susceptibility to damage to the outer surface by abrasion formed martensite is not
`removed.
`,
`
`When the stress is very high, e.g. in high velocity traffic, considerable risks
`remain as the resistance to rupture is not sufficient because of inadequate tenacity
`and the danger of the formation of abrasion martensite exists.
`An object of the present invention is to develop a rail wheel which has a
`tensile strength in the rim of at least 900 N/mm2 without necessarily involving
`expensive heat treatment and a yield point of at least 650 N/mmz. having a high
`resistance to rupture, a good abrasion resistance and in spite of this, not being
`susceptible to the formation of abrasion martensite.
`According to the present invention there is provided a rail wheel in which at
`least the wheel rim consists of a steel having the following composition:—
`
`5
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`

`

`1.452,450
`
`0.12
`
`95' carbon
`
`0.70
`
`1’0 silicon
`
`5.0
`
`“a manganese
`
`0.025
`
`“a nitrogen
`
`0.4
`
`0.4
`
`0.4
`
`2.0
`
`0.5
`
`0.2
`
`“a niobium
`
`”0 vanadium, but
`
`0,0 niobium + vanadium
`
`0., copper
`
`T’o molybdenum
`
`“-3 zirconium
`
`0.01
`
`9-; boron
`
`0.3
`
`0.1
`
`‘?{, titanium
`
`‘33; metallic aluminium
`
`to
`
`to
`
`to
`
`to
`
`to
`
`to
`
`to
`
`to
`
`to
`
`to
`
`to
`
`to
`
`to
`
`0.04
`
`0.20
`
`3.5
`
`0.005
`
`0
`
`0
`
`0.002
`
`0
`
`0
`
`0
`
`0
`
`0
`
`0
`
`remainder being iron and the normal low impurities.
`
`is possible, but not preferred, to replace (substitute) 1
`It
`manganese by chromium.
`A preferred composition contains minimum proportions of molybdenum of
`0.05%, zirconium of 0.02%, boron of 012023;) and
`titanium of 0.01%.
`Very good results are attained by a composition having
`
`to l.5‘,’/g; of the
`
`0.07
`
`0.20
`
`4.0
`
`0.04
`
`0.007
`
`0.005
`
`to
`
`to
`
`to
`
`to
`
`to
`
`to
`
`0.12
`
`‘32; carbon
`
`0.50
`
`9; silicon
`
`5.0
`
`90' manganese
`
`0.12
`
`3;, niobium
`
`0.012
`
`0,; nitrogen and
`
`0.025
`
`°;‘, metallic aluminium.
`
`Furthermore it is preferred to provide a minimum proportion of carbon of 0.09%
`and/or manganese to 4.590. A minimum proportion of 0.39;, molybdenum may be
`useful.
`
`In a particularly preferred embodiment not only the wheel rim consists of
`such a steel. but the whole wheel (solid wheel) is made of such a steel.
`Surprisingly it has been shown that a rail wheel of a steel as defined above can
`have a tensile strength of up to or over 1,000 N/mm2 with a yield point of
`750—1,000 N/mm2 and with a high yield point ratio. Despite this the rail wheel has
`tenacity against rupture and shows no tendency towards the formation of abrasion
`martensite in use.
`In production it is expedient to ensure a low hydrogen content in the steel,
`for which various treatments are possible. The steel can be melted low in hydrogen
`and/“or the hydrogen content can be reduced by one of the known steel degassing
`treatments.
`
`Another measure consists in precipitating the hot-formed wheels or wheel
`rims for the purpose of the removal of hydrogen at room temperature or elevated
`temperature. preferably in the region between 300 to 400°C. Such measures for
`the removal of hydrogen are known in the art.
`The wheels or wheel rims are preferably hot formed in a heat from the raw
`
`10
`
`15
`
`20
`
`25
`
`35
`
`10
`
`15
`
`20
`
`25
`
`.30
`
`35
`
`

`

`5
`
`ingot to the finished section. Cooling of the finished wheel or wheel rim can
`normally take place in air. In order to permit removal of hydrogen a delayed
`coolling in air is possible. During cooling in air a structure of bainite and ferrite
`resu ts.
`.
`According to a preferred process the wheels or wheel rims are quenched in
`water or in another quenching medium after hot forming. This accelerated cooling
`results in a pure bainite structure which surprisingly has a better resistance to
`rupture than the structure resulting from slower air cooling.
`.
`A particular advantage is seen in that the whole rail wheel can be prepared
`from one material, this material being abrasion-resistant, resistant to rupture and
`not inclined to form abrasion marteusite.
`In Tables 1 and 2 are given eight steels, numbers 1 and 2 showing previously
`known steels used for the wheel rims, numbers 3 to 8 being within the present
`invention. Table 1 gives the chemical composition whereas Table 2 gives the
`15 mechanical properties of the material.
`
`10
`
`5
`
`10
`
`15
`
`TABLE 1
`
`Chemical Composition of the steel of the Rail Wheel or Wheel Rim
`
`W S
`.W 1
`
`Cr
`
`—
`
`Nb
`
`—
`
`N
`
`Mo
`
`Remarks
`
`0.005
`
`—
`
`Rail (‘lass
`
`09177291771
`
`teel No.
`
`Treatment State
`
`C
`
`Si
`
`Mn
`
`Air cooling (L)
`
`2
`
`(L)
`
`0.75
`-.
`0.13
`
`0.25
`
`1.1
`
`0.60
`
`1.0
`
`1.1
`
`-
`
`0.007
`
`‘
`
`TPrior
`Rail Special ClassIArt
`
`—
`
`M 3
`
`0.07
`
`0.30
`
`4.5
`
`—
`
`0.1
`
`‘ 0.011
`
`-
`
`Present Invention
`
`2
`
`Air cooling (L)
`
`,,
`
`4
`
`5
`
`6
`
`7
`
`8
`
`or
`
`water
`
`quenching (W)
`
`according to
`
`Table 2
`
`0.08
`
`0.07
`
`0.09
`
`0.12
`
`0.12
`
`0.42
`
`0.28
`
`0.29
`
`0.28
`
`0.29
`
`4.6
`
`4.2
`
`4.5
`
`4.1
`
`5.0
`
`—
`
`-
`
`—
`
`-
`
`—
`
`I
`
`0.11
`
`0.1
`
`0.05
`
`0.10
`
`0.10
`
`0.011
`
`0.012
`
`0.012
`
`0.012
`
`0.012
`
`—
`
`—
`
`0.37
`
`-
`
`-
`
`,,
`
`s.
`
`,t
`
`W A
`
`ll melts contain 0.005 to 0.025 ”/0 Al.
`
`

`

`TABLE 2
`
`Mechanical Properties of the steels of the Rail Wheel or Wheel Rim
`
`Steel
`No.
`
`Treatment State
`Air Cooling (1.)
`Water quenching (W)
`
`Yield Point
`o N/mm‘
`0.2
`
`Tensile
`Strength
`N/mm2
`"B
`
`Fracture
`Elongation
`[6:5de
`
`Reduction
`of Area
`11%
`
`Impact
`DVMF Test
`-30”C
`Joule
`
`Fatigue strength
`under reverse
`Value
`lSO-V +20°(‘ bending stresses
`Joule
`oBW Nfimm"
`
`1
`
`2
`
`3
`
`l
`
`} Prior Art
`
`1.
`
`l.
`
`1.
`
`l.
`
`550
`
`676
`
`775
`
`1020
`
`062
`
`1130
`
`1070
`
`1069
`
`13.5
`
`11.4
`
`16.4
`
`10.5
`
`17.8
`
`23
`
`22
`
`07
`
`57
`
`72
`
`0
`
`9
`
`137
`
`1111
`
`—
`
`9
`
`11
`
`54
`
`42
`
`32
`
`.125
`
`370
`
`421
`
`483
`
`-
`
`2‘.
`
`3.5
`
`5
`
`6
`
`7
`
`0
`
`1.
`
`w
`
`W
`
`1.
`
`W
`
`L
`
`W
`
`ns
`
`066
`
`1005
`
`880
`
`10-11
`
`1077
`
`1064
`
`on
`
`1117
`
`1189
`
`1080
`
`1230
`
`1266
`
`1261
`
`16.3
`
`10.3
`
`15.8
`
`15.7
`
`16.1
`
`15.9
`
`70
`
`70
`
`64
`
`00
`
`02
`
`64
`
`—
`
`—
`
`02
`
`105
`
`14
`
`96
`
`30
`
`13
`
`11
`
`13
`
`6
`
`The previously known high-carbon steels 1 and 2 have agood tensile strength,
`but poor values for tenacity (toughness). The impact value is low so that these
`steels are inclined to rupture, especially at high traffic velocities and low
`temperatures. They are also inclined to form abrasion martensite.
`On the other hand the rail wheel steels 3 to 8 within the present invention have
`good technological properties for use as rail wheels, The reduction of area is
`
`5
`
`5
`
`1.
`g
`
`$
`
`

`

`5
`
`1,452,450
`
`5W
`
`considerably more than 50"/0 and the impact value according to the DVMF test
`known in Germany or according to the internationally known ISO—V test show
`especially good values at
`temperatures of —30°C and room temperature,
`respectively. Moreover the fatigue strength under reversed bending stresses is
`clearly above 400 N/mmz, as steel numbers 3 and 4 Show.
`Column 2 of Table 1 gives the treatment after heat forming. Cooling in air is
`labelled with (L) and quenching in water with (W). It is surprising that the impact
`values of the samples 5(W), 6(W), 7(W) and 8(W) quenched in water are higher
`than the same samples in the air-cooled state. Therefore, with regard to increased
`resistance to rupture. quenching in water is preferred. The properties of the rail
`wheel steels 3 to 8 are so good that the whole rail wheel may consist of a single
`steel composrtion so as to overcome the difficulties initially mentioned.
`
`WHAT WE CLAIM IS:—
`1. A rail wheel with wheel rim, wheel disc and wheel hub, wherein at least the
`wheel rim consists of a steel having the following composition:
`
`0.04
`
`0.20
`
`3.5
`
`1
`
`0.005,
`
`0
`
`O
`0.002
`
`0
`
`0
`
`0
`
`0
`
`0
`
`0
`
`to ' 0.12
`
`3;; carbon
`
`to
`
`to
`
`to
`
`to
`
`to
`
`to
`7 to
`
`to
`
`to
`
`to
`
`to
`
`to
`
`to
`
`0.70
`
`‘5; silicon
`
`5.0
`
`‘3/0 manganese, or
`
`1.5
`
`.
`
`"/0 chromium together with
`manganese
`totalling
`3.5 to 5.070
`
`0.025
`
`0/0 nitrogen‘
`
`0.4
`
`0.4
`0.4
`
`2.0
`
`0.5
`
`0.2
`
`‘2, niobium
`
`"/0 vanadium, but
`0/0 niobium + vanadium
`
`9/, copper
`
`"/0" molybdenum
`
`“/0 zirconium
`
`0.01
`
`0/O boron
`
`0.3
`
`0.1
`
`‘70 titanium
`
`2/0 metallic aluminium
`
`the remainder being iron and the normal low impurities.
`2. A rail wheel according to claim 1 wherein the steel includes at least 0.05"/o
`molybdenum, at least 0.02‘,’/o zirconium, at least 0.002"/o boron and at least 0.01°/0
`titanium.
`3. A rail wheel according to claim 1 wherein the steel composition is
`
`0.07
`0.20 7
`
`4.0
`
`0.04
`
`0.007
`
`0.005
`
`to
`to
`
`to
`
`to
`
`to
`
`to
`
`0.12
`0.50
`
`0/0 carbon
`°/, silicon
`
`5.0
`
`0/o manganese
`
`0.12
`
`0/o niobium
`
`0.012
`
`7% nitrogen and
`
`0.025
`
`”/3 metallic aluminium.
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`4O
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`

`

`1 .452.450
`M“
`4. A rail wheel according to any one of the preceding claims wherein the steel
`contains at least 0.09“; carbon.
`5. A rail wheel according to any one of the preceding claims wherein the steel
`contains at least 4.5“; manganese.
`6. A rail wheel according to any one of the preceding claims wherein the steel
`contains at least 0.3"0 molybdenum.
`7. A rail wheel wherein at least the wheel rim consists of a steel according to
`claim 1 substantially as herein described.
`8. A rail wheel wherein the whole wheel consists of a steel as defined in any
`one of the preceding claims.
`9. A rail wheel according to any one of the preceding claims wherein the
`wheel rim or wheel is cooled in air after hot forming (hot shaping).
`l0. A rail wheel according to any one of claims 1 to 8 wherein the wheel rim or
`wheel is cooled in water after hot forming.
`
`10
`
`10
`
`MEWBURN ELLIS & CO.,
`Chartered Patent Agents,
`70/72 Chancery Lane,
`London W.C.2.
`Agents for the Applicants.
`
`
`Printed for Her Majesty’s Stationery Ofiiee by the Courier Press, Leamington Spa, 1976.
`Published by the Patent Ofi‘ice, 25 Southampton Buildings, London, WCZA. 1AY, from
`which copies may be obtained.
`
`