Date

November 1981

Document Type

Thesis

Degree Name

M.S.

Department

Dept. of Materials Science

Institution

Oregon Graduate Center

Abstract

In the last fifty years railroads have increasingly installed continuously welded rail (CWR) in mainline track, although at current installation rates there will not be significant amounts in secondary lines until the year 2000. CWR is welded in the plant using the flash-butt or oxy-acetylene welding processes and field welded using the thermit welding process. The latter is the only process presently used for repair welding rail. The chief disadvantage to the thermit welding process is its high failure rate due to inherent susceptibility to defects. Recently the electroslag welding process has been adapted to weld railroad rail. This investigation entailed the development of suitable weld metal alloys for the electroslag welding of railroad rail. Alloys were selected according to their ability to achieve a 24 Rockwell C minimum hardness at the rail head given the weld cooling rate. Alloying elements were added via the filler wire and/or the consumable guide tube. Welds were made on 136 lb/yd standard carbon railroad rail and then sectioned for various mechanical property tests and microscopic examination. Two alloys were developed which matched or bettered rail steel mechanical properties. A 21/4Cr-1Mo filler wire and a mild steel guide tube produced a bainitic weld metal deposit at the same strength level and a higher dynamic fracture toughness than the rail steel. A weld metal deposit produced by a high carbon (0.65 C) filler wire and a composite guide tube produced a weld whose strength was slightly less than the rail steel, but whose dynamic fracture toughness was much higher. This filler metal produced a fine pearlitic microstructure both at the rail head and at the rail base.

Identifier

doi:10.6083/M4959FHV

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