Material Properties and Weldability of Steels Used in Aged Bridges

Abstract

In order to obtain basic information for maintenance, repair and reinforcement of aged steel bridges, mechanical properties and weldability of steels used in aged bridges were investigated.

The contents of sulfur were relatively much in steels used in bridges constructed before 1960. The mechanical properties of aged steels were almost the same as those of SS400 and SM400. However, the Charpy absorbed energy of aged steels at 0°C were extremely low. Welding defects were observed in the repair welded parts of aged steel bridges. Although a weld cracking test was performed on the same steel of which the chemical compositions were not suitable for welding, weld crack was not generated. That might be because of the small thickness of steel and the mechanical conditions of welded joints. That is, patch plate welded joints with small thickness generated the small restraint during welding. The results indicated the importance of investigating chemical compositions and the mechanical conditions of welded joints for evaluation of the weldability of aged steels.