Abstract
This experiment is the continuation of former report (v). The results are summerized as follows:
(1) If the soft steel (rimmed and killed) with 0.1-0.2% C be pickled and broken immediately, we can always find the fish-eye-like defects on the fracture of tensile test pieces. And the appearance of this defects (with round or irregular round shape, bright surface and gas-pipe-like hole in the centre) is similar to fish-eye or bird-eye in the welded steel.
(2) The tensile properties and the appearance of defects hardly vary with its heat treatment or duration of pickling.
(3) This defect does not occur during the pickling.
(4) This defect vanishes, if the pickled test piece be left long time in theroom or boiled several hours in water.
(5) It is supposed that this defect also would be occured by the same cause as the normal flakelike defect of special structural steel and the difference of its appearance be caused by the difference of mechanical or plastic properties of steel against the stress.
