FORMABILITY OF EXPERIMENTAL HY-130/150 STEELS.
UNITED STATES STEEL CORP MONROEVILLE PA
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Laboratory studies were initiated on steels having yield strengths of 92 to 169 ksi to establish correlations between bend-test results and tension-test results. The results of plane-strain bend tests on 14- and 38-inch-thick specimens showed that bend angle depends on the test setup and thus is not a broad indicator of formability. However, onset of surface cracking was found to depend on the true surface strain of the bend specimen regardless of the test setup. Thus true surface strain, which can be conveniently determined from the specimen curvature ratio of specimen thickness, h sub o, to outside bend radius, r sub o appears to be the best indicator of formability in the bend test. The results of tension tests indicated that specimen curvature in the bend test correlated satisfactorily with reduction of area in the tension test. Thus, formability by plane-strain bending can be predicted from simple uniaxial tension tests. On the basis of a minimum reduction of area of 60 percent for the experimental HY-130150 steels, minimum inside bend radii from 0.4 inch for 14-inch-thick plate to 7.1 inches for 4-inch-thick plate are predicted. These bend radii indicate that the experimental HY-130150 steels are capable of meeting the forming requirements for submarine hulls.