Problems related to slow strain rate test performance and specimen characterization in austenitic corrosion resistant alloy tubes

Slow strain rate testing is a method that is fast and has a strong potential for ranking alloys for material selection purposes. However, it is a test method that is subject to different issues that may affect the results and lead to inconsistent conclusions. This paper demonstrates that the specimen surface morphology resulting from the final grinding of the material has an impact on the performance of the material. Longitudinal polishing is recommended to avoid the increase of crack nucleation sites by the intersection with of the slip planes that are active during plastic deformation. With regard to the testing conditions, the effect of the filling rate on the pressure and the H₂S concentration in the solution at high temperature was analyzed for a given test environment. The values of the reduction in area are critical to the acceptance of the material. For this reason, the repeatability and reproducibility of this parameter as well as the uncertainty of its measurement were evaluated using the ANOVA method for different operators and types of fracture surface. Finally, special attention was paid to the characterization of the primary fracture surface and the gauge section of the tested specimens of two different corrosive-resistant alloys using scanning electron microscopy and their subsequent classification according to the NACE TM0198 standard.