PROCESS FOR PRODUCING FROGS OF RAILWAY SWITCHES

PROCEDE DE FABRICATION DE COEURS DE CROISEMENT POUR AIGUILLAGE DE CHEMIN DE FER

English Abstract

A b s t r a c t
In a process for producing frogs of railway switches or
rail pieces located in the area of switches which is hit by
the wheels comprising a highly wear-resistent surface layer,
which is travelled upon by the wheels, of an age-hardening
steel of the composition
C 0.01 to 0.05 % Al 0 to 0.2 %
Si 0.01 to 0.2 % B 0 to 0.1 %
Mn 0.01 to 0.2 % Zr 0 to 0.1 %,
Co 0 to 15 %
Mo 1.5 to 6 %
Ni 7 to 20 %
Ti 0.1 to 1 %
Cr 0 to 13 %
the surface layer to be travelled upon by the wheels is
applied by explosion plating or electron beam welding or
roll plating onto a base body of a well weldable steel,
in particular a steel comprising not more than 0.24 % C,
not more than 0.04 % P and S, respectively, not more than
0.65 % Si and not more than 1.7 % Mn.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY OR
PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. Process for producing frogs of railway switches or
rail pieces located in the area of switches which is hit by
the wheels, in which process a highly wear-resistent surface
layer, which is travelled upon by the wheels,of an age-
-hardening steel of the composition
C 0.01 to 0,05 % A 0 to 0.2 %
Si 0.01 to 0.2 % B 0 to 0.1 %
Mn 0.01 to 0.2 % Zr 0 to 0.1 %
Co 0 to 15 %
Mo 1.5 to 6 %
Ni 7 to 20 %
Ti 0.1 to 1 %
Cr 0 to 13 %
is applied onto a base body of well weldable steel,
characterized in that the surface layer travelled upon by
the wheels is applied by explosion plating or electron beam
welding or roll plating onto the base body of well weldable
steel, in particular a base body containing ?0.24 % C,
?0,04 % P and, respectively, S, ? 0.65 % Si and 1.7 % Mn.
2. Process as claimed in claim 1, characterized in
that, after having applied the surface layer to be travelled
upon by the wheels and in particular after having applied
said layer by electron beam welding, aging is effected at
temperatures of 350 to 450 °C, in particular at 400 °C.

- 8 -
3. Process as claimed in claim 1 or 2, characterized
in that the surface layer to be travelled upon by the wheels
is applied in a thickness of 12 to 25 mm, in particular
15 to 20 mm.

Description

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PROCESS FOR PRODUCING FROGS OF ~AILWAY SWI~CHES
BACKGROVND OF THE INVENTION
Field of the Invention
The invention refers to a process for producing frogs
of railway switches or rail pieces located in the area of
switches which is hit by the wheels, in which process a
highly wear-resistent surface layer, which is travelled
upon by the wheels, of an age hardening steel of the
composition
C 0.01 to 0,05 ~ Al O to 0~2 %
Si 0.01 to 0,2 % B O to 0~1 %
Mn 0,01 to 0~2 ~ Zr O to 0-1 %
Co O to 15 %
Mo 1O5 to 6 %
Ni 7 to 20 %
Ti 0.~ to 1 %
Cr O to 13 %
is applied onto a base body of well weldable steel.
Description of the Prior Art
From EP-A-105 864 there have already become known frogs,
in particular frog tips of a steel for railway crossings or
railway switches, the tip of which or, respectively, their
surface layer to be travelled upon by the wheels consists of
the above-mentioned age-hardening steel. The stress exerted
~, .

1 3 1 36 1 0
on frog tips is particularly high when the wheel travels
from the wing rail onto the frog tip and increases to an
uncomparatively high degree with increasing axle load and,
above all, with increasing travelling speeds, so that con-
siderable deformations may occur at the frog tip, whichdeformations considerably reduce the life-time of the frog.
The material proposed in said EP-A was, according to this
EP-A~applied by building-up welding onto a base body of
a standardized rail steel. The production of the whole frog
from such a highly wear-resistent steel is relatively
expensive and the use of composite materials in combination
with such a wear-resistent layer within the area of the gap
over which pass the wheels, or, respectively, in the frog
tip provides the possibility to connect without problems
by welding at the connecting areas the base materials and,
respectively, the standardized rail steel. Connecting the
base materials by welding can be performed without special
precautions by means of electrical flash butt welding
machines. On account of the material of the wear-resistent
layer having, according to this known process for pro-
ducing such frogs, been produced by building-up welding
onto the base body of standardized rail steel, there resulted
still the difficulty that no homogenous thermal connection
could be obtained without simultaneQusl~ reducing the
quality. Application of weax-resistent materials by buildin~-
-up weldinghas always as a consequence interming~ing with
the base material and thus th~ formation of a m~re or less

1313610
distinct zone of inhomogeneities formed on account of the
process. The advantages of the materials used for the
wear-resistent layer can thus not fully be utilized when
working according to the known process for build-up welding.
SUMMARY OF THE INVENTION
. . _
The invention now aims at providing a process of the
initially mentioned type, which allowSto connect the material
for the running surface with the base body homogeneously
according to a thermal process, for thus increasing the
quality of the frog. In particular, the formation of an
inhomogenous boundary layer between the different materials
of the frog piece or rail piece shall be avoided. For
solving this task, the process according to the invention
essentially consists in that the surface layer travelled
15 upon by the wheels is applied by explosion plating or
electron beam welding or mill plating onto the base body
of well weldable steel, in particular a base body containing
~ 0,24 % C, ~0~04 % P and, respectively, S, ~ 0~65 % Si
and ~1.7 % Mn. The explosion plating is a principally
known technology for connecting equal or different materials
along a metal surface. In the explosion plating process~
the connection results by a high pressure acting during a
short time interval, whereby the metal surfaces are brQught
one relative to the other into distances of atomic dimen-
25 sions by plastic deformation. AS a rule, the melting tempera-
ture is not attained within the binding zone and therefor
it is also spoken of a pressure welding process. The explosion

1 3 1 36 1 0
plating process ~rovides the possibility to connect also
metals~which would give rise to the formation of brittle
phases in case of fusion welding. When selecting the
material, proposed according to the invention, for the
wear-resistent layer, an intermingling zone is avoided when
applying the explosion plating process and the advantages
with respect to the wear-resistance of the running surface
being travelled upon by wheels are reliably obtained.
Analoguous considerations apply for the mill plating.
The material selected for the wear-resistent layer
fulfills the premises required for electron beam welding
proposed as an alternative. Only materials of relatively low
carbon content may be applied as a layer by el~ctron beam
welding and the use of the initially mentioned material for
the wear-resistent layer provides the premises required for
this purpose. Also when applying electron beam welding there
results an only very thin connecting layer, so that
inhomogeneities are substantially avoided. In both cases,
there remains a base body of well weldable steel, so that
frogs can be welded to connecting rails without difficulties.
Such frogs are, in contrast to known materials for frogs
of particularly high wear resistance such as austenitic
manganese steel as well as highly upgraded low-alloy steels,
easily weldable with connecting rails and can thus be used
without difficulties in the consistently welded track of
the modern railroad track. In comparison thereto, welding
of the austenitic manganese steel and also of the frog tips

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of quenched and annealed low alloy steels with rail steels
requires on account of the limited welding properties of
such steels special precautions,which are relatively
expensive.
A further improvement of the homogeneity of the thermal
connection between the material used for the layer being
travelled upon by the wheels and the base member can be
obtained, if, after having applied the layers to be travelled
upon by the wheels and in particular after having applied
said layer by electron beam welding, an aging is effected at
temperatures from 350 to 450 C, in particular 400 C. At
temperatures of 400 C, there results the additional
advantage that simultaneously the gap filling welding bead
is stress-annealed, noting that the base material itself
is included within the group of well weldable materials.
By means of the mentioned processes/there can be applied
in a preferred manner running surfaces having a thickness
of 12 to 25 mm, in particular 15 to 20 mm.
As a whole, there is thus provided a frog and,
respectively, a wing rail~in which a well weldable base
material of a favourable price is combined with a layer
consisting of an extremely wear-resistent material and
having a small volume and thus also a low weight to a
composite material which can be used within the area to be
travelled upon by the wheels and being subjected to the
highest stress. Thus it becomes possible to produce at
favourable costs high-quality frogs which can without further

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precautions be used for welding consistent rail tracks.
In particular when using for applying the wear-resistent
layers and, respectively, the surfaces to be travelled upon
by the wheels the explosion plating process~one can do
with a rela-tively low layer thickness of 15 mm, whereas
the thicknesses applied in the electron beam welding process
are approximately 20 mm for providing to a certain degree
for a fire loss. When usin~ the electron beam welding
process, there has primarily to be considered the upper
limit of 0.03 ~ carbon. This upper limit is of no importance
when using the explosion plating process.