The development of railroads promoted the innumerable railway bridges building in Brazil mainly at the end of 19th and the beginning of the 20th century. In those period, girders and other bridges components were built with a growth production demand promoting challenges in the control and volume of manufacturing production process taking into account that the metallurgical knowledge was in early stages. Nowadays, innumerable railway bridges are still in service and their proper maintenance is sometimes ignored. Thus, this work determine the type of metallic material and failure mechanism of structural arch and “L” shapes girders components from Desengano Bridge taking into account that some repairs were performed during their life span. The investigation conducted in this work showed that the structural components analyzed were constructed by puddle or wrought iron process, which is characterized by high levels of P and S in their composition. Meanwhile a reinforcement plate welded to the arch girder was added in a corrective maintenance of the bridge, especially because the plate material matches the current structural low carbon steel. The fracture surface revealed that the crack has dendritic inclusions with typical hot solidification crack aspect. Finally, it should be considered that metallic parts of any ancient bridge, especially those ones containing rivets as an essential rule, in first instance cannot be repaired in situ by welding.

铁路的发展主要在19世纪末和20世纪初促进了巴西无数铁路桥梁的建设。在那个时期，考虑到冶金知识还处于早期阶段，因此随着生产需求的增长建造了大梁和其他桥梁部件，从而推动了制造生产过程的控制和数量方面的挑战。如今，无数的铁路桥梁仍在使用中，有时会忽略其适当的维护。因此，考虑到在其使用寿命期间进行了一些维修，这项工作确定了Desengano桥的结构拱和“ L”形大梁部件的金属材料类型和破坏机理。这项工作进行的调查表明，所分析的结构部件是通过水坑或锻铁工艺构造的，其特征在于其P和S的含量较高。同时，在桥的矫正维护中增加了焊接到拱梁的加固板，特别是因为板材料与当前的结构低碳钢相匹配。断裂表面表明，裂纹具有树枝状夹杂物，具有典型的热凝固裂纹特征。最后，应该考虑到，任何古代桥梁的金属零件，特别是那些包含铆钉的金属零件，首先都不能通过焊接进行现场修复。同时，在桥的矫正维护中增加了焊接到拱梁的加固板，特别是因为该板的材料与当前的结构低碳钢相匹配。断裂表面表明，裂纹具有树枝状夹杂物，具有典型的热凝固裂纹特征。最后，应该考虑到，任何古代桥梁的金属零件，特别是那些包含铆钉的金属零件，首先都不能通过焊接进行现场修复。同时，在桥的矫正维护中增加了焊接到拱梁的加固板，特别是因为该板的材料与当前的结构低碳钢相匹配。断裂表面表明，裂纹具有树枝状夹杂物，具有典型的热凝固裂纹特征。最后，应该考虑到，任何古代桥梁的金属零件，特别是那些包含铆钉的金属零件，首先都不能通过焊接进行现场修复。