Method of making a tee rail having a high strength base

A method of making a base-hardened tee rail comprising the steps of:

• providing a carbon steel tee rail having a composition including, in weight percent:
• Carbon:
• 0.74-0.86;
• Manganese:
• 0.75-1.25;
• Silicon:
• 0.10-0.60;
• Chromium:
• 0.30 Max;
• Vanadium:
• 0.01 Max;
• Nickel:
• 0.25 Max;
• Molybdenum:
• 0.60 Max;
• Aluminum:
• 0.010 Max;
• Sulphur:
• 0.020 Max;
• Phosphorus:
• 0.020 Max;
• and a remainder being iron and residuals, the steel tee rail provided at a temperature between 70° and 800° C.;
• cooling the steel tee rail at a cooling rate that, if plotted on a graph with xy-coordinates with the x-axis representing cooling time in seconds and the y-axis representing temperature in ° C. of the surface of the base of said steel tee rail, is maintained in a region between:
• an upper cooling rate boundary plot defined by an upper line connecting xy-coordinates (0 s, 800° C.), (80 s, 675° C.), (110 s, 650° C.) and (140 s, 635° C.);
• and
• a lower cooling rate boundary plot defined by a lower line connecting xy-coordinates (0 s, 700° C.), (80 s, 575° C.), (110 s, 550° C.) and (140 s, 535° C.);
• and
• wherein the cooling rate from 0 second to 80 seconds plotted on the graph has an average within a range of between about 1.25° C./sec and 2.5° C./sec, the cooling rate from 80 seconds to 110 seconds plotted on the graph has an average within a range of between about 1° C./sec and 1.5° C./sec;
• and the cooling rate from 110 seconds to 140 seconds plotted on the graph has an average within a range of between about 0.1° C./sec and 0.5° C./sec.