Comparison of mechanical behavior between longitudinal lap-welded joints and transverse fillet welded joints of high strength steel

Mechanical behavior of twenty-eight longitudinal lap-welded joints made of high strength steels (HSS) under tension load was investigated by experimental study. Weaknesses due to traditional deformation measurements for fillet welded joints can be perfectly solved by digital image correlation techniques (DIC). The effect of parameters (e.g. weld size, weld length and mismatch ratio) on mechanical properties (e.g. ultimate strength, failure modes, weld ductility and fracture angle) of longitudinal fillet welds and transverse fillet welds, which was introduced in detail in previous work by the authors, were compared. Generally, because of the difference on the combination of shear force and tension force, the fracture angle of longitudinal welded specimens (around 50) were much more divergent from transverse welded specimens (around 20) even though both of them failed at welded zone (welded zone only refers to weld metal in this paper), resulting that the mean strength of longitudinal welded specimens were only 0.58 time of transverse welded specimens. Conversely, the mean deformation capacity of longitudinal welded specimens was almost 4.0 times of transverse welded specimens. Moreover, it was confirmed that the predicted loads of EC3 and AISC Specification were close and slightly conservative for all specimens.