The invention relates to a process for manufacture of a railroad track part, in particular of a large points part, where rail parts such as a frog point and connector rail comprise a first and a second material of differing composition.
The invention further relates to a railroad track part, in particular to a large points part, comprising rail parts of differing materials joined by welding, of which materials one is carbon steel and another austenitic manganese steel.
A frog with block-like frog point is known from DE-AS 1 284 439, where the pointed part comprises self-hardening steel and the connecting rails standard rail grade steel. The pointed part and connecting rails are oil-quenched after welding.
Also known is the joining of a frog point made of austenitic manganese steel to connecting rails of carbon steel via an intermediate layer of a low-carbon austenitic steel. After making the first welded join, homogenizing follows. Consequently, to join cast austenitic manganese steel to carbon steel, an intermediate layer made of steel is used, where during welding a specified sequence must be maintained and after the first welding operation a heat treatment must be performed, without this however assuring in the final analysis that any harmful influences are ruled out during the second welding operation on the intermediate layer made of special steel. Furthermore, the intermediate layer must have a certain length in order to attain a thermal separation between the welding points.
A process for manufacture of a frog is known from AT 401 359 B, where a frog point is, before being welded to connecting rails, subjected to a selective heat treatment in order to achieve a fine-lamellar pearlite structure.
DD 263 482 A5 relates to a process for the manufacture of points frogs. To improve the wear strength of the frog, it is provided that a wheel contact surface is provided by explosive plating or electron-beam welding on a base element comprising readily weldable steel.
The use of an austenitic manganese steel for manufacture of weldable parts, in particular in points frogs, is described in DE 28 46 930 C2.