Failure of HY-100 and HSLA-100 steels as a function of stress state and microstructural conditions.

摘要

The motivation of this study arises from the need to predict failure of high toughness naval steels subject to multiaxial tensile stresses. These failure criteria should take into account not only the multiaxial stress states arising from the loading conditions but also ranges of microstructures present in weldments of steels such as the HY-series and HSLA-series steels. The tensile failure behavior of weldments of two typical high strength naval steels, HY-100 and HSLA-100, has been studied as a function of stress state and microstructural condition. Although their minimum yield strength levels (100 ksi) are similar, these two steels differ in terms of inclusions and carbides, which typically play major roles in tensile failure of steels.;The current study addresses the failure of HSLA-100 and HY-100 steels from several perspectives. Multiaxial tensile fracture initiation criteria, in the form of the failure limit diagrams, have been experimentally determined using the circumferentially notched specimens. In addition, the associated failure mechanisms have also been examined in terms of the contrasting microstructural characteristics of the two steels. The influence of microstructure has also been examined by studying the failure behavior of HSLA-100 steel weldments as well as the HY-100 with a pronounced microstructurally banded structure. The influence of strain path on failure has also been briefly examined. Finally, theoretical analyses on damage evolution have been performed in order to link damage accumulation to material's failure.;The current study indicates that the ductile fracture of HY-100 and HSLA-100 steels is largely dictated by inclusions and not by deformation behavior, and that ductility is primarily controlled by inclusion characteristics such as inclusion content and inclusion shape.