2. Objectives

2.1 Metallurgy

The metal of the two rail ends, almost in contact, is progressively heated to the melting point on the surface of the ends, so that the iron vapors prevent oxidation of the faces to be welded. The forging that follows has an active stroke of 15 to 16 mm interpenetration, under a pressure of 60 MPa, resulting in complete recrystallization and the two ends behaving as a monoblock.

AC welding machines, with their often high sinusoidal overvoltages, often produced large sparks and craters, which were filled with various inclusions not expelled by the forging process (Figures 1 and 2...