Frog, in particular frog point, for rail crossing or rail switches as well as process for producing same

In a steel frog for rail crossings and rail switches, the frog point or, respectively, the surface of the frog being travelled upon by the wheels consists of an age-hardening steel having the composition ______________________________________ C 0.01 to 0.05% Ti 0.1 to 1% Si 0.01 to 0.2% Cr 0 to 13% Mn 0.01 to 0.2% Al 0 to 0.2% Co 0 to 15% B 0 to 0.1% Mo 1.5 to 6% Zr 0 to 0.1% Ni 7 to 20% ______________________________________ The frog is manufactured such that the surface being travelled upon by the wheels is applied by build-up welding onto a base body consisting of nominal rail steel.

The invention refers to a frog, in particular a frog point, of steel for 
rail crossings or rail switches as well as to a process for producing such 
a frog. Frogs are subjected to high load and high wear when being 
travelled upon by the wheels of a rail vehicle and this particularly if 
the wheels roll from a wing rail onto the frog point or, respectively, 
from a frog point onto a wing rail. The frog point is subjected to 
particular high stress when a wheel rolls from the wing rail to the frog 
point and is unproportionally increased with increasing axle loads and, 
above all, with increasing traffic speed, so that considerable 
deformations can occur at the frog point, which deformations substantially 
reduce the life time of the frogs. 
For avoiding the effect of a wheel impact on the frog point there are known 
frogs in combination with movable wing rails and, respectively, with 
movable frog points. By applying the frog point onto the wing rail and, 
respectively, by applying the wing rail against the frog point there is 
provided an interrupted rolling surface. Such frogs require, however, 
special switching mechanisms and thus are correspondingly complicated and 
expensive. 
It is further known to use frogs of materials showing special properties. 
Known materials with particularly good wear properties and high load 
capacity at the area of wheel transition are hard manganese steels as well 
as low alloy steels specially heat-treated for quality improvement. These 
steels must, however, be well weldable with the adjoining frog parts and, 
respectively, with the rail for the purpose of being used in an 
uninterruptedly welded track of the up-to-date railroad superstructure. 
Welding of the hard manganese steel and also of the heat-treated low alloy 
frogs with the rail materials requires, however, in view of the limited 
welding properties of these steels special measures which equally are very 
expensive. It is also known to use at the area where the wheel travels 
from one part onto the other a composite material, the wear-resistent 
component thereof being applied at said area by building-up welding.

With all these embodiments of frogs there are used at the area where the 
wheel travels from one part onto the other, i.e. at the wing rail and at 
the frog point, either same materials or different materials with only 
minor differences in strength. It has surprisingly been found that when 
using exclusively for the frog point a material of highest strength and 
thus of highest wear resistance, the wing rail can also within the area 
where the wheel travels from one part to the other remain in normal 
condition (in the condition as rolled). 
According to the invention it is now proposed to make the frog point and, 
respectively, the surface of the frog being travelled upon by the wheels 
of an age-hardening steel having the composition 
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C 0.01 to 0.05% Ti 0.1 to 1% 
Si 0.01 to 0.2% Cr 0 to 13% 
Mn 0.01 to 0.2% Al 0 to 0.2% 
Co 0 to 15% B 0 to 0.1% 
Mo 1.5 to 6% Zr 0 to 0.1% 
Ni 7 to 20% 
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When using such a steel, the whole frog point can consist of such a steel, 
noting that manufacturing of the frog point can be effected from a piece 
of such a steel by cutting operation or by material detaching work. In 
this manner it is possible to manufacture in an economic manner frogs 
which meet the highest load requirements. The steel type used according to 
the invention for the frog point has up till now not been used in railroad 
superstructure and is included within the group of martensite-hardening 
steels. The steel is well weldable and well workable after a solution 
treatment. Such types of steels are characterized by the property of 
assuming a very high hardness accompanied by a good tenacity on account of 
martensite conversion and/or precipitation of intermetallic phases when 
being aged at 200.degree. to 600.degree. C. The obtainable strength 
amounts to approximately 1800 to 2200N/mm.sup.2. 
In a preferred manner, the inventive frog and, respectively, frog point is 
made by producing the running surface for the wheel by build-up welding 
onto a base body consisting of nominal rail steel. Build-up welding can be 
effected to obtain a thickness of approximately 15 mm.