Abstract: Medium and high-strength steels working in harsh environments are susceptible of suffering of mechanical properties loss due to hydrogen presence. In order to avoid catastrophic failures, the estimation of the fracture toughness in environment is necessary, but sometimes it is not convenient the use of standard tests; an alternative to the aforementioned traditional fracture mechanics specimens are Circumferential Notched Tensile specimens (CNT), which consist of cylindrical tensile specimens that incorporate a circumferential notch. In this work, CNT specimens subjected to acid aggressive environments, generated by cathodic polarization, are used to estimate the fracture toughness in environment, KIEAC. For this purpose, two methodologies, one proposed by Singh Raman et al. in the 2000's and another by Cayón et al. in the 2010's, are compared. Both formulations rely on similar classic fracture mechanics bases, differing mainly in the way to correct the effects of non-centering of the ligament, caused by asymmetries in the growth of annular cracks in CNT specimens. Both are finally validated to estimate KIEAC, showing good accuracy within the ±L15%.

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