Microstructure of Various Steels (hypoeutectoid, eutectoid and hypereutectoid)
- Selection of the sample- Select a representative sample that accurately depicts the material's unique microstructural characteristics. Based on the needs of the analysis, the dimensions and form of the sample are to be taken into consideration.
- Sectioning- Section the sample using a precision cutting machine. The sections are ought to be divided perpendicularly to the interest areas. Use a coolant or lubricant when cutting to avoid overheating and sample damage.
- Mounting- Insert the divided sample into a mounting substance (often a thermosetting resin) to sustain and uphold the specimen's integrity in the ensuing stages. Make sure the sample is oriented correctly to get the analysis plane desired.
- Grinding- Using abrasive papers or grinding stones, coarsely grind the mounted sample to get rid of extra material and create a smooth, even surface. To improve the surface finish, use finer abrasive sheets.
- Polishing- To achieve a mirror-like surface, polish the sample with polishing papers of varying grit sizes to eliminate scratches and grinding marks. For the last stages of polishing, use a polishing cloth dipped in a polishing suspension (usually alumina or colloidal silica).
- Etching- An essential first step in exposing the material's microstructure is etching. Choose the right etchant according to the content being examined. Nital is used as an etchant for eutectoid steels. To ensure even and regulated etching, apply the etchant for a predetermined amount of time.
- Rinsing and drying- To get rid of any last bits of debris or etchant, thoroughly rinse the polished and etched sample with water or an appropriate solvent. Use a gentle, lint-free cloth or a stream of air to dry the specimen.
- Mount removal- If required, use a heated mount remover or an appropriate solvent to remove the mounting material.
- Final cleaning- Use a mild detergent or solvent to clean the sample and get rid of any leftover contaminants. Ensure the sample is completely dry before examining the specimen under a microscope.
- Microscopic examination- Place the prepared specimen on the microscope stage. For a thorough examination of the microstructure, use the proper magnification and lighting. Take pictures or draw sketches for your documentation.
- Analysis and reporting- Conduct any required measurements or analyses in accordance with the study's goals. Note down all the results, including phases, microstructural characteristics, and any anomalies.
- Preservation (optional)- If the specimen needs to be preserved for an extended period, applying a protective layer (like lacquer) can be preferred to stop oxidation.
