STRUCTURE AND PROPERTIES OF THERMITE WELDS IN PREMIUM RAILS.

Thermite welds were used to join combinations of premium rails and AREA Controlled Cooled Carbon rails (i. e. , standard rails). The premium rails comprised head-hardened rails and CrMo, CrV and Cr alloy rails. A major objective was to determine the feasibility of joining premium rails to each other and to standard rails with the thermite welding process. The objective was met in that metallurgically sound welds were produced using either 'standard' or 'alloy' thermite charges. Other objectives were to determine mechanical properties and metallurgical structures of the weld-metal and of the heat-affected zones. The 'alloy' weld-metal was stronger than 'standard' weld metal but had less tensile ductility. Both types exhibit ductilities of only 2-6 percent reduction in area and impact energies of only 1. 5-2. 8 Joules at 20 degree C. Tensile and impact specimens show tensile ductilities of 19-60 percent reduction in area and only 2. 6-6. 9 Joules for impact energy.