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, welded to a bainitic steel member, including boron up to 0.01% by wt, molybdenum 0.2 to 3% by wt, manganese 0.3 to 3% by wt, with the weld subsequently tempered to provide enhanced fatigue resistance by a post welding heat treatment.

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 "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 joint component 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, welded to (ii) a bainitic steel member, including boron up to 0.01% by wt molybdenum 0.2 to 3% by wt manganese 0.3 to 3% by wt and preferably including copper up to 6% by wt nickel up to 6% by wt chromium up to 6% by wt, with the weld subsequently tempered to provide enhanced fatigue resistance by a post welding heat treatment. Clearly, for the joint component to be used to form a rail joint, then the bainitic steel member needs to have the same industry-standard rail profile as a rail of austenitic manganese steel. Furthermore, the former would normally then be welded to one end of a pearlitic steel rail length. The bainitic steel member is preferably a length of rail of industry-standard profile. For joining to a frog etc., the bainitic steel member would again need to have a matching profile to that of the austenitic manganese steel frog member. A second aspect of the invention given in claim 3, is directed to a method of manufacturing such a joint component. The post-welding heat treatment is preferably effected in factory controlled conditions, and is preferably effected in a flash butt welding machine, whereby close monitoring and control of the heat treatment parameters can be made.

Claims: A joint component 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, welded to (ii) a bainitic steel member, 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, with the weld subsequently tempered to provide enhanced fatigue resistance by a post welding heat treatment. A joint component as claimed in Claim 1, wherein the bainitic steel member is a length of rail of industry-standard profile. A method of manufacturing the joint component defined in Claim 1 or Claim 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 (ii) a bainitic steel member, including boron up to 0.01% by wt molybdenum 0.2 to 3% by wt manganese 0.3 to 3% by wt which optionally includes copper up to 6% by wt nickel up to 6% by wt chromium up to 6% by wt, and then subsequently tempering the weld to provide enhanced fatigue resistance by a post welding heat treatment. A method as claimed in Claim 3, wherein welding of the austenitic manganese steel member to the bainitic steel member is effected in a flash butt welding machine. A method as claimed in Claim 3 or Claim 4, wherein the post welding heat treatment is effected in 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, C21D9