Materials Chemistry

Biography

Biography: Feyzan Ersoy

Abstract

Ferritic/martensitic T91 steel is an important structural material for the Lead Bismuth Eutectic (LBE) cooled Generation IV (Gen IV) reactors. One of the biggest challenges of using this material is though its mechanical properties are reported to degrade when the material is subjected to a combination of LBE and stresses. This phenomenon is known as Liquid Metal Embrittlement (LME). Therefore, a careful investigation of the interaction between LBE and T91 is required to assess the effect of LBE on the mechanical properties of the steel, define the conditions where LME occurs and determine possible mitigation strategies for Gen IV applications. Even though the degradation of mechanical properties of the T91 material was screened during tensile tests by ductility losses, more dedicated tests such as Fracture Toughness Tests (FTT) should also be performed for design purposes. However, FTT in LBE are technologically challenging. Conventionally, FTT are made based on the unloading compliance and/or potential drop methods. Unfortunately, LBE might chemically attack the clip gages used in the unloading compliance method, while the electrical conductivity of LBE interferes with the potential drop method. Moreover, LBE can also degrade the steel parts in the test set-up, posing additional challenges. Therefore, alternative methods and dedicated set-ups are needed for FTT in LBE. In this study, challanges in performing fracture toughness tests in LBE environment will be discussed. FTT results of T91 steel will be presented including the reference tests in inert environment and comparing them with the tests in LBE.