MICROSTRUCTURAL DEGRADATION PROCESSES IN ELEMENTS OF BRIDGES ERECTED AT THE TURN OF THE 19TH AND 20TH CENTURIES
Journal Title: Scientific Journal of the Military University of Land Forces - Year 2010, Vol 155, Issue 1
Abstract
Structural degradation processes are taken into account in old steels. It is particularly visible in the steels manufactured at the turn of 19th and 20th centuries. Structural degradation processes consist of the decomposition of pearlite or bainite areas into carbides and ferrite. Also, separation processes (carbides and nitrides) are taken into account. These structural changes strongly influence the rudimentary mechanical properties, i.e. an increase in material hardness and strength, and a decrease in ductility, impact resistance and crack resistance. These processes are more intense in puddled steels (produced until the end of 19th century) rather than in cast steels. In the paper, the authors present the study of a cyclic behaviour of old puddled steel taken from the oldest bridge in Wroclaw: the Piaskowy Bridge (erected in 1861). With the ASTM E64 the measurement stand and an experimental procedure were set up. The M(T) specimens were tested on the testing machine MTS 810 with the force controlling method. The tests were performed for 10 Hz frequency and the sinusoidal force signal. The specimens were tested in two states: the post operational state and the normalised one.
Authors and Affiliations
Grzegorz LESIUK, Mieczysław SZATA
Keywords
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