Results of bending fatigue strength on specimens with synthetic CGHAZ microstructure which were smooth and flawed at the surface were discussed in respect of flaw size and mechanical properties. Specimens were grooved to cause similar stress concentration as that existing at the weld toe. Artificial flaws were single and series of Vickers indentations of the size comparable to the characteristic dimensions of CGHAZ microstructure. Threshold stress intensity factor is a linear function of strength and a parabolic function of flaw size. Bending fatigue strength increases with the strength in the case of significant flaw size and/or harder CGHAZ microstructure. But, it is also increased by local plastic deformation which has happened at the weld toe in the case of insignificant flaw size and/or softer CGHAZ microstructure.
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