Surface imaging of metallic material fractures using optical coherence tomography

Area of Science:

• Materials Science
• Mechanical Engineering
• Optical Metrology

Background:

• Fracture analysis is crucial for understanding machinery failures.
• Current methods like scanning electron microscopy (SEM) are time-consuming and require sample removal.
• In situ analysis of fracture surfaces is highly desirable for rapid damage assessment.

Purpose of the Study:

• To demonstrate the capability of optical coherence tomography (OCT) for metallic surface topography after fracture.
• To differentiate between ductile and brittle fracture modes using OCT.
• To evaluate OCT as a potential replacement for SEM in fracture analysis.

Main Methods:

• Utilized a custom-built swept source optical coherence tomography (OCT) system.
• Acquired height profiles of fractured surfaces from steel (OL 37, OL 52) and a Sn-Sb-Cu alloy.
• Compared OCT results with scanning electron microscopy (SEM) images for validation.

Main Results:

• OCT successfully generated detailed height profiles of the fractured metallic surfaces.
• Distinct topographical features allowed differentiation between ductile fractures (steel samples) and brittle fracture (alloy sample).
• OCT imaging correlated well with SEM analysis, confirming its diagnostic capability.

Conclusions:

• Optical coherence tomography (OCT) is a viable technique for characterizing metallic fracture surfaces.
• OCT can distinguish between ductile and brittle fracture modes.
• OCT presents a promising, potentially in situ, and cost-effective alternative to SEM for fracture analysis.