In the previous report, the effects of specimen width, plate thickness and welding residual stress on the fracture characteristics of 5083-O plate and 5183 welds, in which crack-like flaws are present, have been
investigated. In this report, the effects of notch acuity, through-thickness notch length, surface notch size and welding misfabrication on the fracture strength are investigated.
From the experimental results, the following conclusions are obtained:
1) The saw cut with the notch root radius 0.1mm is equivalent to a natural crack from the viewpoint of ductile fracture strength.
2) In order to obtain the fracture strength of these materials, the standard test specimen for the deep notch test, with 400mm width and 60mm edge cut, is proposed.
3) The ductile fracture strength of a specimen with a comparatively long and deep surface notch depends on the 0.2% proof stress of the plate. On the other hand, that with a comparatively short and shallow surface notch depends rather on the tensile strength.
4) The ductile fracture strength is considerably greater than the 0.2% proof stress, even in the case that a surface crack-like flaw and large welding mis-fabrication are present. However, the misalignment should be restrained as small as possible.
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