Mechanical Properties of Rolled H Section Steel Jointed by Newly Developed Flash Welding System.

In the civil engineering and architecture, welding for large sectional steel members, such as I section and H section, are usually required. A flash welding system, by which large I section or H section can be welded for a short time, was newly developed. A series of experiments was carried out in order to know the characteristics of the flash welded joints. The joint efficiency of welded joints by flash welding was 100 % for the specimens with reinforcements and 93 % for without reinforcements. The fatigue strength of welded joints with reinforcement was about 50 % of that of the base metal. The fatigue strength of welded joints without reinforcement was 75 % of that of the base metal. After a couple of fatigue cracks had propagated, in case of welded joints with reinforcement, ductile fracture of occurred at the toe. On the other hand, in welded joints without reinforcement, fracture occurred at the bond or at HAZ (the heat affected zone). In case of fracture at the bond, fracture was brittle, and in case fracture at HAZ, fracture was ductile. Flash welded joints with reinforcement had the same grade of fatigue strength as arc welded butt joints with reinforcement and the non-load-carrying fillet joints by arc welding. The flash welded joints without reinforcement had the same grade of fatigue strength as the arc welded butt joints without reinforcements.