Experimental investigation and low-cycle fatigue life prediction of welded Q355B steel

39 experiments are conducted to study the low-cycle fatigue behavior of welded Q355B steel, including 15 welded steel bars under uniaxial loading and 24 welded tubular specimens under axial-torsional loading. There are two locations vulnerable to fracture. A large strain loading range (>0.011) makes it more likely to fracture in the welding material. Fatigue analysis shows that the plastic development of the welded steel is non-uniform, especially under large loading ranges. The existence of axial and shear strain (1) decreases torsional and tensile loading capacity, respectively, (2) makes the loading capacity enter the stage of rapid decline in advance, (3) decreases the fatigue life. Together with experimental results from other literature, fatigue parameters are obtained. Applying these parameters into a critical plane model for multi-axial damage (Kandil-Brown-Miller model), the fatigue lives (in range of 100–3600) of 39 specimens are predicted