High-strength solid wheels and tires for railroad traction vehic

Details High-strength solid wheels and tires for railroad traction vehic High-strength solid wheels and tires for railroad traction vehic

1994-06-30

1996-07-09

Stormer, Russell D.

Railway wheels and axles

Wheels

148583, 148662, 148335, B60B 1700

Patent

active

055337708

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

The present invention concerns high-strength solid wheels and tires of forged and rolled alloyed steel, quenched and tempered, for railroad traction vehicles and cars.
Solid wheels and tires for railroad vehicles have previously been made of steel containing 0.48 to 0.52% carbon and 0.75 to 0.80% manganese as determined in accordance with UIC Code 812-3/V, 5th edition, Jan. 1, 1984.
The most practical steel is steel R7. Its tensile strength (Rm) is 820 to 940 N/mm.sup.2, its break elongation (A.sub.5) at least 14%, and its notch-impact work at least 15 Nm in ISO U sections. All these levels are for 20.degree. C. (room temperature).
Steel R7 is preferably employed for block-braked solid wheels in cars with high axle loads.
From known wheel fractures and from the research into their etiologies conducted on specific steels it has been concluded that one cause of UIC-Code steel breakage is insufficient tenacity.
High-speed trains are also equipped with wheels of UIC Code 812-3/V Steel R7. More rigid specifications deriving from heavier axle loads, higher speeds, and greater braking forces, especially in conjunction with the constant braking that occurs in mountainous regions, can also lead to wheel fracture.


SUMMARY OF THE INVENTION

The object of the present invention is accordingly a steel for high-strength solid wheels and tires for railroad traction vehicles and cars that will be much more tenacious at the strengths typical of existing steels, R7 for example, and that will be less likely to fracture even at constant braking.
This object is attained in accordance with the present invention as recited in the claims.
A steel with a specific ratio between major, alloying, and companion elements will be a steel of high purity and uniformity. Furthermore, the heat treatment in accordance with the present invention ensures a structure of excellent tenacity at high strength and of especially endurance.


DESCRIPTION OF THE PREFERRED EMBODIMENTS

The invention accordingly concerns specifying an innovative material for solid wheels and tires for railroad vehicles along with a heat treatment for solid wheels and tires of that material.
Compositions are provided with specific ratios of carbon to chromium to nickel, with specific upper thresholds of silicon, and with particularly low upper thresholds of phosphorus and sulfur that will subsequent to quenching and tempering yield steels for solid wheels and tires with strengths equal to or surpassing those of the Steel R7 predominantly employed today and with on the other hand far superior tenacities, especially break tenacities. These compositions are as follows:


______________________________________ carbon: 0.380-0.420 silicon: .ltoreq.0.250 manganese: 0.400-0.600 phosphorus: .ltoreq.0.012 sulfur: .ltoreq.0.005 chromium: 1.000-1.500 molybdenum: 0.300-0.600 nickel: 0.700-1.200 aluminum: 0.015-0.040 nitrogen .ltoreq.0.008. ______________________________________
In the preceding composition of the steel, the ranges of chromium, molybdenum, and nickel can, furthermore, be changed to the following, in percent by mass:


______________________________________ chromium: 1.00-1.30 molybdenum: 0.30-0.50 nickel: 0.70-1.00. ______________________________________
Temperatures and cooling procedures are provided for quenching and tempering that will ensure such superior tenacities and provide the wheels and tires with minimal strengths similar to those specified in the UIC Code 812-3/V for Steel R7. These temperatures and cooling procedures are as follows: or oil at room temperature at approximately 20.degree. C.; to room temperature at approximately 20.degree. C.
The tenacities of the ferrite-perlite carbon-manganese steels previously known from UIC Code 812-3/V cannot be much improved. Steel composition accordingly needs thoroughgoing revision, with due attention of course to purity, homogeneity, and maximal isotropy. Acceptable break tenacities accordingly necessitate, in departure from the ferrite-perlites while re

REFERENCES:
patent: 2129671 (1938-09-01), Brunner
patent: 2197365 (1940-04-01), Kjerrman
patent: 2368418 (1945-01-01), McCarroll et al.
patent: 3009844 (1961-11-01), Connert
patent: 3135600 (1964-06-01), Hardwick et al.
patent: 3163565 (1964-12-01), Wada
patent: 4861549 (1989-08-01), Khare

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