The influence of hydrogen on the fatigue life of metallic leaf spring components in a vacuum environment

Hydrogen is used as a process gas in vacuum environments for semiconductor manufacturing equipment. If hydrogen dissolves in metallic components during operation it can result in hydrogen embrittlement. In order to assess if hydrogen embrittlement occurs in such a vacuum environment a special fatigue test has been developed. Accelerated life time tests at 2 Hz bending (R = -1)were conducted on 3 different designs of metallic leaf-spring specimens. In total, 5 types of metals were investigated: Stavax ESR, Custom 465, AISI 301, Inconel 718 and Ti–6Al–4V. Reference tests in air were performed to validate results with fatigue data in literature, followed by fatigue tests in a controlled hydrogen environment. Fatigue tests in Ar-gas with 100 ppm H2 were conducted to simulate the vacuum conditions. For all specimens, no hydrogen-related damage or decrease in fatigue life due to the presence of hydrogen was observed. Therefore, a low partial hydrogen pressure of 100 ppm in vacuum is not detrimental to the life time of metallic leaf springs.