U.S. patent application number 12/456764 was filed with the patent office on 2010-12-23 for railway wheel alloy.
This patent application is currently assigned to AMSTED RAIL COMPANY, INC.. Invention is credited to Mark S. Shirley.
Application Number | 20100322815 12/456764 |
Document ID | / |
Family ID | 42234615 |
Filed Date | 2010-12-23 |
United States Patent
Application |
20100322815 |
Kind Code |
A1 |
Shirley; Mark S. |
December 23, 2010 |
Railway wheel alloy
Abstract
A steel alloy, particularly adapted for the manufacture of
railway wheels is provided. Such alloy comprises essentially, in
weight percentage, carbon 0.57-0.87, manganese 0.50-1.00, silicon
less than 0.85, chromium 0.10-0.70, molybdenum less than 0.20, with
the balance essentially iron. A second embodiment alloy is also
provided. Such alloy comprises a steel railway wheel alloy,
comprising, in weight percentage, carbon 0.50-0.80, manganese
0.50-1.00, silicon less than 0.85, chromium 0.10-0.70, molybdenum
less than 0.20, phosphorus less than 0.05, sulfur less than 0.05,
with the balance essentially iron.
Inventors: |
Shirley; Mark S.; (Geneva,
IL) |
Correspondence
Address: |
AMSTED INDUSTRIES INCORPORATED;TWO PRUDENTIAL PLAZA
SUITE 1800, 180 N. STETSON
CHICAGO
IL
60601
US
|
Assignee: |
AMSTED RAIL COMPANY, INC.
|
Family ID: |
42234615 |
Appl. No.: |
12/456764 |
Filed: |
June 23, 2009 |
Current U.S.
Class: |
420/87 ; 420/104;
420/105 |
Current CPC
Class: |
C22C 38/18 20130101;
B60B 17/0006 20130101; C22C 38/04 20130101 |
Class at
Publication: |
420/87 ; 420/105;
420/104 |
International
Class: |
C22C 38/22 20060101
C22C038/22; C22C 38/18 20060101 C22C038/18 |
Claims
1. A steel railway wheel alloy, comprising, in weight percentage,
carbon 0.50-0.80, manganese 0.50-1.00, silicon less than 0.85,
chromium 0.10-0.70, molybdenum less than 0.20, with the balance
essentially iron.
2. A steel railway wheel alloy, comprising, in weight percentage,
carbon 0.50-0.80, manganese 0.50-1.00, silicon less than 0.85,
chromium 0.10-0.70, molybdenum less than 0.20, phosphorus less than
0.05, sulfur less than 0.05, with the balance essentially iron.
3. A steel railway wheel, comprising, in weight percentage, carbon
0.50-0.80, manganese 0.50-1.00, silicon less than 0.85, chromium
0.10-0.70, molybdenum less than 0.20, with the balance essentially
iron.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention provides a railway wheel alloy and,
more particularly, a railway wheel alloy particularly adapted for
use in the manufacture of cast steel railway wheels.
[0002] In the manufacture of cast steel railway wheels, it is
desirable to utilize a steel alloy that is able to be hardened to
provide adequate wear resistance, while also providing adequate
resistance to thermal cracking. The mechanical strength of steel
can be improved by the addition of alloying elements such as
chromium, manganese, and molybdenum. However, such alloy additions
must be carefully chosen to minimize increased costs as well as
balancing the possible degradation of the improved properties that
desirable amounts of such alloys add.
[0003] Thermal-mechanical shelling and spalling are the two
predominant causes of tread damage found on railway wheels in
service. This tread damage results in the significant levels of
pre-mature wheel removal from service. The phenomenon of
thermal-mechanical shelling is generally experienced in the
heavy-haul coal, ore and grain services, where the environment is
conducive to this type of failure. The contributing factors related
to these services include high normal forces when the railcars are
loaded, and when the wheels are subject to long and steep grades in
mountainous regions. The normal forces from railcar loading are,
for the railroads, ideally at the maximum allowable for the wheel
designs. Spalling involves the transformation of tread surface
material into the brittle martensite phase. Sliding of the wheel on
the rail causes this material transformation. The present alloy
development is aimed to reduce or eliminate the damage caused by
thermal-mechanical abuse or sliding of the wheel on the rail.
[0004] Three components of thermal-mechanical shelling together
allow the tread damage to occur. The mechanical portion of the
process is a rolling contact fatigue. The rolling of the wheel
provides the cyclical stresses to drive the progressive failure.
The thermal component, introduced by the drag braking, not only
contributes thermal stresses in the wheel but also reduces the
material's ability to resist mechanical loading through reduced
material strength at elevated temperature. The final component of
this progressive failure is time-at-temperature. The longer the
wheel is at an elevated temperature, the greater the number of the
loading cycles, which are needed to initiate and propagate the
cracks, will occur.
[0005] It should also be understood that the desirable alloy of the
present invention can be utilized not only in cast steel wheels,
but also in other forms of manufacture of railway wheels including
forging.
[0006] Accordingly, it is an object of the present invention to
provide an alloy particularly adapted for the manufacture of
railway wheels.
[0007] It is also an object of the present invention to provide an
alloy particularly adapted for the manufacture of cast steel
railway wheels having improved hardness and, accordingly, wear
resistance, plus resistance to thermal cracking.
SUMMARY OF THE INVENTION
[0008] One specific alloy is directed at the affects of
thermal-mechanical shelling.
[0009] This is chromium-silicon-molybdenum alloy. This alloy has
shown great promise in heavy haul service. Molybdenum and chromium
increase the high temperature properties of the steel. These
improved high temperature properties will increase the minimum
temperature at which fatigue cracks will initiate and therefore
decreases the time the tread material is above the critical
temperature. By reducing these two components of fatigue and
time-at-temperature, fewer cracks will initiate and propagate in
the tread. All three alloying elements increase the steels yield
and tensile strength. This will reduce the subsequent propagation
of any cracks that do initiate at elevated temperatures while the
wheel is rolling under normal operational conditions. An additional
benefit of the molybdenum and chromium alloys is improved wear
resistance which will lengthen the normal operational life of the
wheel.
DETAILED DESCRIPTION
[0010] Railway wheels which an alloy as set forth in Example 1
below were cast and subjected to various performance field
tests.
EXAMPLE 1
[0011] Railway wheels were cast with the following alloy
composition, in percentage by weight: carbon 0.57-0.87, manganese
0.50-1.00, silicon less than 0.85, chromium 0.10-0.70 and
molybdenum less than 0.20.
[0012] Based on these field test results and supporting laboratory
tests, the alloys of the present invention are more resistant to
shell tread condition than the normal carbon type steel. In fact,
in normal freight car service, mileage performance of the cast
steel wheel in accordance with the present invention is seen to
approach 400,000 miles.
EXAMPLE 2
[0013] Railway wheels were cast with the following alloy
composition, in percentage by weight: carbon 0.57-0.87, manganese
0.50-1.00, silicon less than 0.85, chromium 0.10-0.70, molybdenum
less than 0.20, phosphorus less than 0.05 and sulfur less than
0.05.
[0014] Based on these field test results and supporting laboratory
tests, the alloys of the present invention are more resistant to
shell tread condition than the normal carbon type steel. In fact,
in normal freight car service, mileage performance of the cast
steel wheel in accordance with the present invention is seen to
approach 400,000 miles
* * * * *