抄録
In order to investigate the notch sensitivity of Mn-Si high tensile steels, we have performed Lehigh Slow Bend Test using specimens with or without weld bead of FL-16 and B-17.
Following results are obtained from the test :
(1) Concerning the notch sensitivity, the tested high tensile steels are superior to the rimmed steels, and they are approximately on the same level or a little inferior to the killed steels.
(2) There is a tendency that the fracture and ductility transition temperatures fall to a lower value as silicon content increases.
(3) The ductility transition temperature of specimens having weld bead is considerably higher than that of without weld bead. However, as to the fracture transition temperature, there is no significant difference between these two kinds of speciment with and without weld bead.
(4) Comparing the results of specimens with weld bead of FL-16 and B-17, there is no significant difference, but FL-16 weld bead shows a little better ductility than B-17 weld bead.
(5) The notch ductility of thicker plates is generally inferior to that of the thinner plates.
(6) There are no significant differences about the test pieces taken from the top or the bottom of ingot.
