Microscopy of precipitates in stainless steel landing gear and their effect on fatigue life

Variation in fatigue life of aerospace components remains an issue that requires further study. Landing gear produced in stainless steel with 1.6 wt% titanium was chosen for surface and bulk chemical analysis, as well as microscopy. Surface corrosion was characterized with x-ray photoelectron spectroscopy (XPS). Optical emission spectroscopy (OES) confirmed the precise bulk metal composition. Non-metallic precipitates were quantified in polished cross sections by automated scanning electron microscopy (SEM), where the same particles were also observed on the machined exterior surfaces. Similarly, nanoscale intermetallic Ni₃Ti nanoparticles and Ti-rich precipitates were evaluated by automated transmission electron microscopy (TEM). Surface corrosion and the formation of these particles is discussed in relation to their potential effect on fatigue life of the landing gear.