Digital Repository, ECF14, Cracow 2002

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Local Approach Treatise of High Y/T - Ratio Steels in the Ductile-to-Brittle Transition Region

Last modified: 2013-02-10


The full utilization of high strength steels, particularly modernthermomechanically processed steels (TMCPs), is usually hindered not by materialproperties, but rather by inadequate design procedures. In many cases the inadequacy isperceived as lack of suitable assessment methods or more commonly, their scope has notbeen defined with respect to high strength steels of this type. Current study focuses on theseaspects with respect to fracture toughness based measures of material performance inrelation to material strength.In the current work ductile to brittle transition regime is treated by focusing on MasterCurve toughness description of fracture toughness. The general effects of Y/T ratio tomaterial toughness are modeled using local approach methods. The results of numericalsimulations demonstrate that the high Y/T ratio does not need to translate to low toughnessperformance either with respect to the transition regime nor the upper shelf but that thetoughness characteristics are more so controlled by microstructural features affectingfailure micromechanisms, and that transition region criteria are not to be presented solelyon the basis of indirect measures, such as tensile properties. In the current study, thetransition region properties of a high Y/T ratio S460ML TMCP steel are found to besuperior in comparison to conventional S355J2G3 steel, which is being used as areference.

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