Fig. 7 Fractured fatigue sample: (a) BM, (d) As-welded SZ; Cross
section: (b) and (c) BM, (e) As-welded SZ
The crack in the PAZ/BM interface is shown in Fig. 8. The two layers in
the SZ were indicated in Fig. 8 (b). The debonding between layer-1 and
layer-2 was observed. It contributed to the crack initiation of the
as-welded SZ sample under a maximum stress of 210 MPa. The instantaneous
crack propagation was indicated in Fig. 8 (a). The instantaneous crack
propagation contributed to the instantaneous elongation and resulted in
the abortion of fatigue test.