Preheat conditions of fillet weld for steel bridge fabrication

Abstract

According to the specification for Highway Bridges, the preheat temperature is determined by thickness of plate, PCM and diffusible hydrogen. The standard of the minimum preheat temperature has been determined based on the results of y-groove weld cracking test. Therefore, it is considered to require the superfluous preheat temperature, when this standard is applied to the fillet welding. However, the discussion of preheat temperature with the results of fillet weld cracking test has been still insufficient. In this paper, to discuss the standard for fillet welding, we examine the cold cracking susceptibility and the HAZ hardness distributions of the fillet welds using 50mm thick plates whose PCM ranges from 0.24% to 0.27% with various preheat temperatures. Using the present results, we propose a modified standard of the minimum preheat temperature for fillet welding.