FCP Report No. 179

Effects of Rail-End Beveling on Thermite Welding

by

Jeffrey N. Withee
Frederick V. Lawrence
Department of Civil and Environmental Engineering

Abstract

Thermite welds were fabricated using standard, squeezed, and vibrated weld methods and evaluated to determine the benefits of rail end beveling. The rail end beveling consisted of trimming back the rail base. The rail trimming was performed so that base metal to base metal contact would occur in the rail head of the squeezed weld. Welding was completed on an I-beam fixture having a hydraulic ram that allowed a squeeze force or vibration to be introduced during weld solidification. Three types of welds (standard, squeezed and vibrated) were created for testing. Standard welding required no ram movement, squeezed welding brought the rail ends together until a set compressive force was achieved, and the vibrated weld involved vibrating the weld metal with the ram until a measurable resistance occurred.

The welds were tested and examined to determine tensile properties, hardness, fatigue life, porosity (using confocal microscopy), and weld microstructure. The squeezed weld with the rail end beveling treatment achieved base metal to base metal contact in the rail head and a smaller overall width of weld metal than the other two weld types. Squeezed and vibrated weld metal exhibited lower porosity than the standard weld metal. The squeezed weld exhibited fatigue performance superior to both the standard and vibrated welds. No notable differences were observed in tensile and hardness measurements made on the three welds. Squeezed welding improved weld properties by expelling thermite metal and reducing the size of the largest pore.

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