Class 5 includes steels and stainless steels with less than 2% carbon. These widely used ferrous alloys vary in microstructure and hardness depending on carbon content and thermal treatment. Metallographic preparation is generally routine, but structure-specific etching and polishing may be required to reveal features like pearlite, ferrite, and martensite.
Overetching can obscure pearlite or martensite; underetching may fail to reveal boundaries.
Harder phases like martensite may polish unevenly compared to surrounding ferrite.
Cold work or grinding stress may introduce artifacts unless properly relieved.
Soft phases like ferrite may smear slightly if force is excessive during polishing.
Standard abrasive cutting is sufficient. Use coolant to avoid heat-induced microstructural changes.
Compression mounting is commonly used. Ensure alignment to preserve grain orientation if needed.
Start with SiC papers, progressing to finer grits. Minimal pressure reduces deformation in soft areas.
Use diamond suspension on a medium-nap cloth. Final polish with colloidal silica for clear grain structure.
Grain boundaries and phases are clearly visible
No overetched or underetched zones
Minimal polishing relief across phases
No surface strain or cold work artifacts