Analysis of Microstructure and Mechanical Properties of Wrought Iron

Several wrought iron samples cut out from an old bridge built in 1910 in Šilutė have been received for metallographic examination and mechanical testing. The bridge still caries a local traffic, but it needs urgent repair, thus, the yielded information on material characteristics is of high importance. The results of our examination of these specimens are presented in the paper. A metallic matrix of the specimens is very low in alloying elements (C, Si, Mn, Cr, Mo, S, etc.) with the exception of phosphorus (ca 0.15 %) and copper (ca 0.1 %), however, it contains a sufficient amount of slag inclusions. Fibre-shaped slag inclusions distributed in a metallic matrix have a certain influence on mechanical properties, particularly on plastic behaviour of wrought iron. The results of tensile strength of the examined specimens are similar to the respective properties of modern steel containing ca 0.1…0.15 % C, but the plastic behaviour of the wrought iron specimens differs highly from plasticity of modern steel. The arc welding of wrought iron has also been tested and the obtained results are discussed in the paper