This work is about evaluating the behavior facing HIC of high strength steels by means of the Small Punch Test (SPT). It can be considered as a quasi-non-destructive test in comparison to structural integrity analysis of large components. It was developed during the 80’s with the purpose of estimating the embrittlement grade of nuclear components reducing the amount of material employed. During the last years it has been successfully employed in the evaluation of mechanical properties of different materials and creep behavior. Also approximations for the fracture properties estimations have been carried out using this method. Although a reference standard that includes the tensile and fracture parameters estimations by SPT does not exist, a European Code of Practice (CWA 15627:2008) was recently developed. In addition a European standard is in preparation, including the ultimate research and the backup of the most relevant groups.
In this work, high strength steels behavior facing stress corrosion cracking (SCC) or hydrogen Embrittlement (HE) processes are analyzed by means of the Small Punch Test (SPT). The evaluation of the response of materials facing environmental damage processes requires a different consideration if cracks are present on the material or not. In a first stage the study carried out tries to analyze the behavior without cracks, using the threshold stress (σscc) parameter. The aforementioned parameter is obtained from slow strain rate tensile tests (SSRT), which involves its own particular disadvantages. Thus the aptitude of the SPT to obtain the threshold stress is studied, evaluating the influence of variables such as the solicitation rate.
In the second part of the work, specimen geometry and test conditions are proposed for the SPT, in order to evaluate the susceptibility facing SCC and HE in presence of cracks for the materials studied. In this case, the fracture toughness parameter that describes the crack initiation process (Khe) will be evaluated and validated by conventional tests based on fracture mechanics. The influence of variables, such as test solicitation rate on the results, is analyzed in order to obtain a qualitative methodology to evaluate mechanical-environmental damage processes by SPT means. For the SPT tests carried out, common Small Punch specimens of 10×10 mm of section and 0,5 mm of thickness are used for σscc determination.
