Abstract
Method D, Double cantilever beam (DCB) test is used for design/fitness-for-service, material qualification and specification purposes. Material resistance to propagation of environmental cracks is expressed in terms of a critical stress intensity factor KISSC or Klimit values. Usually, these values are determined without considering the experimental uncertainties and material variability.
However, when comparing the sulfide stress corrosion cracking (SSC) performance of different materials, the quantification of experimental uncertainties becomes of fundamental importance. If the fracture toughness in sour media results of different materials present similar values, the evaluation of material variability and experimental uncertainties can determine if a steel is different or not from another.
In this work, two methods for determining the uncertainties associated with NACE TM0177 Method D are presented. The first one consists in the estimation of the experimental uncertainties in the measured parameters and the Monte Carlo method is used to obtain the uncertainty in Klimit. The second method treats the experimental data as sets that have an intrinsic variability (i.e.: variability of the medium, material, etc.) and the Monte Carlo method is used to obtain the uncertainty in Klimit.
