Development and experimental verification of a corrosion fatigue assessment method for highly-stressed engine components in E85 biofuel

Engine components, such as injection systems, encounter a large number of load cycles (N > 107) during their lifetime and are exposed to potentially corrosive media such as fossil fuels. For this reason, corrosion fatigue in the very high cycle fatigue (VHCF) regime has to be taken into account for reliable fatigue design. To reduce carbon dioxide (CO2) emission, fossil fuels are blended with biogenic components. Biofuels are potentially more corrosive than unblended fuels due to the hygroscopic properties, e.g. ethanol, which is added to gasoline fuels. There is not much known about the corrosion fatigue behavior of high-strength chromium steels in bio-fuels, yet. Indeed investigations show that biofuels reduce the number of load cycles to failure of engine components significantly [1]. Therefore, it is essential to investigate the corrosive impact of fuels with biogenic components by performing corrosion fatigue tests. In the current paper, the impact of corrosion fatigue was investigated on notched and unnotched specimens of stainless 17% chromium steel 1.4016 (X6Cr17), AISI 430 in air and E85 biofuel (gasoline fuel with 85% ethanol added). The results were obtained at a stress ratio of R = 0 with different testing rigs to investigate the influence of testing frequencies (f = 20, 150Hz). The test results represent the basis for a concept that will be able to estimate the impact of corrosion fatigue in the VHCF region