Tratamento térmico de normalização em trilhos perlíticos soldados por processo aluminotérmico: propriedades mecânicas e microestruturais

Abstract

The present work aims to analyze eutectoid and hypereutectoid rails welded through aluminothermic process that were heat treated according to the Normalization process. To support the results, the rails’ mechanical properties were compared in 3 different circumstances: the data provided by the manufacturers for new rails, collected data for rails welded through the aluminothermic process, and collected data for rails welded through the aluminothermic process that received Normalization heat treatment. In the result analysis, tensile testing, hardness testing, micrographs and fractographs are presented. Samples of eutectoid and hypereutectoid welded rails were used, which when only welded exhibited completely fragile behavior in the field as well as in trials. After heat treatment, eutectoids recovered their ductile behavior and had an increase in maximum tension of approximately 30%, elongation 5 times greater when compared to the condition without treatment, and reduction of area approximately 9 times greater. The hypereutectoids, despite still having a tendency to fragile behavior, showed considerable improvements in their mechanical properties with increases greater than 20% in maximum tension, and stretches and reductions in area respectively greater than 4 and 7 times greater when compared to the condition without heat treatment.