The Effect of Microstructural Banding on Failure Initiation of HY-100 Steel

摘要

Microstructural banding of a hot-rolled HY-100steel plate was accentuated by cooling slowly from the austeniteregion, which resulted in alternating layers of soft, equiaxed ferrite,and hard "granular ferrite." The segregation of substitutionalalloying elements such as Ni and Cr was identified as the maincause for the microstructural banding. Such banding inducesanisotropic flow behavior at large strains, with deformationconstrained by "pancake-shaped" bands of the hard granular ferrite.Tensile tests of circumferentially notched HY-100 specimens wereperformed in order to explore the stress dependence of failure inthe slow-cooled as well as the quenched and tempered conditions.The failure behavior of the slow-cooled, microstructurally bandedmaterial exhibited a pronounced susceptibility to a void-sheetmode of failure. However, the absence of carbides within theequiaxed ferrite delays void coalescence and material failure tohigher strains than in a quenched and tempered microstructure,despite the increased susceptibility to shear localization.