Classifications

• • 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
  • C22C38/001—Ferrous alloys, e.g. steel alloys containing N
• • 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
  • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
  • C22C38/38—Ferrous alloys, e.g. steel alloys containing chromium with more than 1.5% by weight of manganese

Definitions

• the invention relates to the use of a fully austenitic nitrogen-containing steel as a material for the production of parts on rail vehicles which are exposed to high loads during the movement of the vehicle.
• the tasks of a wheel set to carry and guide the vehicle on the track can drive and brake forces on the track to transfer and, if necessary, to use the wheel tread as a braking surface for brake pads, of the common wheel or tire materials (pearlitic or ferritic-pearlitic carbon steels with 0.4 to 0.7% by weight carbon, 0.2 to 0.6 %
• silicon 0.5 to 1.0% by weight manganese as a basic analysis, optionally up to 1% by weight chromium, up to 0.3% by weight molybdenum, up to 0.15% by weight vanadium, Yield strength values from 400 to 550 N / mm2, tensile strength values from 800 to 1100 N / mm2) can only be met to a limited extent.
• wheels made from these materials are subject to additional stresses which can lead to premature failure of the wheels, in addition to general wear, even more than in normal
• the block During block braking, the block generates changes in shape due to braking heat in the tire and especially in the full wheel, which leads to the tire loosening on the rim or to tension in the tire or full wheel. These tensions can cause the tire or wheel to burst. They can lead to permanent changes in shape and thus to changes in the track dimension.
• the shape changes also cause residual stress conditions, which have to be added to the basic stress due to the wheel load when the wheel is subjected to static and dynamic loads.
• cold deformation creates a compressive stress state and the braking heat creates a tensile stress state.
• the cyclical change between the two states means a quasi permanent vibration stress in heat and cold. It can lead to thermal cycling cracks on the tread of the wheels.
• the braking surfaces of separate brake disks attached to the wheel or on the axle of a wheel set also have above-average wear.
• the object of the invention is to provide a steel which, when used for solid wheels, wheel tires or wheelset brake disks of rail vehicles, does not tend to the undesirable formation of friction martensite.
• Remainder iron and usual smelting-related impurities which, after solution annealing at 1000 to 1150 o C and cooling to room temperature, have a minimum yield strength Rp o, 2 of 550 N / mm2 and a notched impact strength of at least 150 joules (Iso-V sample) as Use material for the production of solid wheels, wheel tires or wheelset brake discs of rail vehicles.
• Steels of the same or similar composition belong to the state of the art (AT-PS 266900, US-PS 3820980, US-PS 3912503), but nothing is known about the special composition within the known ranges with which the formation is subject to frictional wear of friction martensite avoided.
• the steel to be used according to the invention is fully austenitic and maintains this structural condition in all load conditions. Local transformations of the austenitic structure into a martensitic or martensitic / ferritic structure are also included excluded this steel.
• the low carbon content of the steel to be used according to the invention in connection with the intended high nitrogen contents is decisive for the non-occurrence of these conversion processes.
• the steel to be used according to the invention has the additional advantage that, despite the relatively low initial strength, it strongly solidifies when used on the surface. Nevertheless, the toughness, which ultimately also determines the lifespan of the components, remains the same. In contrast to conventional steels, the toughness values do not drop significantly when the steel is hardened.
• the steel to be used according to the invention can optionally contain up to 0.5% V, up to 0.5% Nb, up to 3% Mo, up to less than 3% Ni and up to 3% Si.
• Vanadium and niobium increase the fine grain and thus have a positive effect on the mechanical properties.
• Silicon in quantities of up to 3% inevitably gets into the steel in the usual melt metallurgical production and does not significantly impair the mechanical properties.
• Molybdenum in an amount up to 3% increases the strength, and nickel than usual Steel companions can also be present in amounts of less than 3% without adversely affecting the properties of the steel.
• the use of a fully austenitic steel is provided as the material for the production of wheel tires of various vehicle wheels, the wheel tires being hardened by a cold expansion after the hot forming.
• This cold expansion of the tire can increase its initial strength and prevent the tendency to flow sideways in the only hot-formed state.
• a variant of the use of the proposed steel according to the invention therefore consists in using the steel for producing wear layers to be applied to the treads of solid wheels and wheel tires or the braking surfaces of brake discs.
• Such a measure is particularly suitable for repairing damaged wheel tires.
• a defective wheel can be removed in the usual way by machining again to form a round tread, the steel to be used according to the invention being applied as a wear layer in a further working step.
• This can be done in a preferred manner by the process of known plasma spraying, in which a layer of a few millimeters in thickness is sprayed on.
• a powder of the basic composition mentioned in the claims can be used.
• the spraying process is also possible for the spraying process to be carried out with a mixture of an ionizing inert gas with nitrogen, which on the one hand prevents nitrogen losses during the spraying process and on the other hand even makes it possible to burn nitrogen, which brings about the desired composition of the wear alloy.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Braking Arrangements (AREA)
• Heat Treatment Of Articles (AREA)

Applications Claiming Priority (4)

Publications (1)

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Family Applications (1)

Country Status (2)

Cited By (8)

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Citations (4)

Family Cites Families (4)

• 1990
  • 1990-07-24 DE DE19904023462 patent/DE4023462C1/de not_active Expired - Fee Related
  • 1990-08-17 EP EP90115739A patent/EP0422360A1/de not_active Withdrawn

Patent Citations (5)

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