FIGURE 1 Specimen.
To study the effect of micro scratches on fatigue life of TC17, rough
specimens were prepared. The machining defect, mainly micro scratches,
were not eliminated by fine grinding and polishing in last process step.
Because of the extremely small size at micron level, optical
interferometer is the most suitable method of measuring the scratches.
ZYGO 3D optical profiler instrument owns numerous advantages: high
measurement precise, non-contact surface measurement, and nanoscale
surface features. The surface topography of specimens, along with the
essential geometric parameter such as depth and width of scratches can
be observed and measured by ZYGO accurately.
As shown in Figs. 2A-D, micro scratches are the main morphological
characteristics for the specimens. Table 1 gives the measurement results
of actual micro scratch depth and width by ZYGO along with\(\sqrt{\text{area}}\) of each specimen. For each scratch, there
cross-sections are measured and take the average value as the final
depth and width. For each specimen with multiple scratches, only three
largest scratches are observed and measured. Specific measurement
methods and precautions are listed in Ref. [18].