Influence of maximum fatigue precracking force on CTOD value of DH36 flux-cored wire CO₂ protection welded joints

CTOD tests were carried out for flux-cored gas protection welded joints of DH36 according to Standard BS7448. The effect of fatigue precracking force on the CTOD value was investigated by analyzing the microstructure and fracture surface of the joint and finite element simulation on the process of fatigue precracking. The results show that the maximum fatigue precracking force has a tremendous influence on CTOD value. When the maximum fatigue precracking force was less than the specified value in Standard BS7448, the test process was prone to pop-in phenomenon, and smaller CTOD value occurred. Conversely, when the maximum fatigue precracking force was close to or exceeding the specified value, the CTOD value would be larger. Thus the Standard should be strictly limited to the maximum fatigue precracking force to ensure the reliability of test results.