Railway joint

Abstract: A weldable austenitic manganese steel joint for railways comprising an austenitic manganese steel member, including manganese 11.5 to 19% by wt, carbon 0.6 to 0.95% by wt, secured by a first weld to a bainitic steel insert, including boron up to 0.01% by wt, molybdenum 0.2 to 3% by wt, manganese 0.3 to 3% by wt, and of relatively short length secured by a second weld to a pearlitic steel member, with heat from the second weld being transferred via the insert to the first weld thereby tempering the first weld.

Description: This invention relates to joints for the rails, frogs etc., of railways, tramways, light rail transit systems etc., all hereinafter collectively referred to as a "railway rails", and to a method of manufacturing such a joint. The advantage is self-evident of inserting a component of high wear resistant, but relatively expensive, steel - conventionally an austenitic manganese steel - at a location of anticipated high wear e.g. at a crossing or frog. Mechanical connections, usually involving fish plates, have been used to secure such austenitic manganese steel components in position, but with the increasing installation of continuously welded rail, there is an increasing demand for an austenitic manganese steel crossing etc., capable of incorporation, by welding, in continuously welded rail track. However, austenitic manganese steel cannot be welded directly to pearlitic steel due to the composition and the differing heat treatments necessary to obtain the properties required of a railway rail. Consequently, the practice has evolved of interposing an insert of a third steel of composition that is weldable to both austenitic manganese steel and to pearlitic steel. GB-A-1 552 392 discloses an insert made of austenitic stainless steel, but being high in Cr and Ni this is relatively expensive and is not the simplest of materials to weld. EP-A-0 070 774 discloses a method of joining a cast manganese steel frog to carbon steel rails in which chrome nickel manganese steel inserts are welded to the frog and then the inserts are welded to the carbon steel rails, the inserts likewise being high in Cr and Ni. Also, another proposal in EP-A-0 467 881 has involved the need to effect a pre or post heat treatment e.g. at 350°C to 1000°C, to refine and temper the weld to provide enhanced fatigue resistance. According to a first aspect of the present invention given in claim 1, there is provided a weldable joint for railways comprising; (i) an austenitic manganese steel member, including manganese 11.5 to 19% by wt carbon 0.6 to 0.95% by wt, secured by a first weld to (ii) a bainitic steel insert, including boron up to 0.01% by wt molybdenum 0.2 to 3% by wt manganese 0.3 to 3% by wt and optionally including copper up to 6% by wt nickel up to 6% by wt chromium up to 6% by wt and of relatively short length secured by a second weld to (iii) a pearlitic steel member, with heat from the second weld being transferred via the insert to the first weld thereby tempering the first weld. Thus, in accordance with the invention, a weldable joint for railways is provided that is not only easily weldable by the use of the relatively cheap bainitic insert, but which advantageously also avoids the need for any pre or post heat treatment. Clearly, for the joint to form a rail joint, then the bainitic insert needs to have the same industry-standard rail profile as a rail of pearlitic steel and a rail of manganese steel. For insertion of a frog etc., again the insert needs to have a matching profile. A second aspect of the invention given in claim 3 is directed to a method of manufacturing such a joint. All welding is preferably effected in a flash butt welding machine, whereby close monitoring and control of the welding parameters can be made.

Claims: A weldable joint for railways comprising; (i) an austenitic manganese steel member, including manganese 11.5 to 19% by wt carbon 0.6 to 0.95% by wt, secured by a first weld to (ii) a bainitic steel insert, including boron up to 0.01% by wt molybdenum 0.2 to 3% by wt manganese 0.3 to 3% by wt and optionally including copper up to 6% by wt nickel up to 6% by wt chromium up to 6% by wt, and of relatively short length secured by a second weld to (iii) a pearlitic steel member, with heat from the second weld being transferred via the insert to the first weld thereby tempering the first weld. A joint as claimed in Claim 1, wherein the bainitic steel insert is a length of rail of industry-standard profile. A method of manufacturing the joint defined in Claims 1 and 2, comprising welding (i) an austenitic manganese steel member, including manganese 11.5 to 19% by wt carbon 0.6 to 0.95% by wt, to one end of (ii) a bainitic steel insert, including boron up to 0.01% by wt molybdenum 0.2 to 3% by wt manganese 0.3 to 3% by wt and optionally including copper up to 6% by wt nickel up to 6% by wt chromium up to 6% by wt, and of relatively short length, and then welding the other end of the bainitic steel insert to (iii) a pearlitic steel member, with heat from the second weld being transferred via the insert to the first weld thereby tempering the first weld. A method of manufacturing the joint defined in Claim 3, wherein welding is effected by a flash butt welding machine.

Inventors: CONNELLY RAYMOND C O EDGAR ALL, PENDLETON DESMOND ROY C O EDGA, CONNELLY, RAYMOND, C/O EDGAR ALLEN ENG. LTD., PENDLETON, DESMOND ROY, C/O EDGAR ALLEN ENG. LTD.
Applicants: ALLEN EDGAR ENG, BRITISH RAILWAYS BOARD, EDGAR ALLEN ENGINEERING LIMITED
Application year: 1993
Main classification: C22C38
IPC codes: B23K35, B23K11