Application of the Incremental Step Loading Technique to Small Punch Tests in Hydrogen Embrittlement

Abstract

In this work, the incremental step loading technique to measure hydrogen embrittlement threshold in steels from ASTM F1624 standard is applied to the Small Punch test technique. For the experimental program, a medium strength steel is employed, simulating the hydrogen embrittlement environment by a cathodic polarization of 5 mA/cm2 in an acid electrolyte mainly consisting of 1N H2SO4 in H2O. Regular standard tests on cylindrical tensile specimens were carried out under the same environment following the ASTM F1624 standard, observing the same trends in both cases, which validates the methodology proposed. In order to adapt the aforementioned standard to small punch testing, the duration of the loading steps had to be modified, proposing much shorter ones according to the Small Punch specimen dimensions and the punch rate taking place in these scenarios, which is pointed in bibliography. This proposal allows to obtain a threshold load by using at least 3 specimens in a total time of around a week.