6. Preheating process design

Based on the chemical analysis of the rail to be welded, we calculate its Carbon Equivalent CE; from this CE, a vertical line allows us to choose the appropriate energy ratio in J/mm ² , depending on whether or not the rail is heat-treated; by following this ratio value horizontally and its intersection with the cross-section of the rail used (whose metric weight is known), we find, along a vertical line, the total electrical preheating energy (figure 12 ).