CAMEO Metallographic Procedure for Case Depth Samples

Significance of the Topic

Case hardening techniques such as carburizing, nitriding, carbonitriding and induction hardening are crucial for producing components with durable, wear-resistant surfaces while maintaining a tough core. Accurate determination of case and effective case depth ensures performance reliability in industries ranging from automotive to aerospace and heavy machinery.

Objectives and Overview

This application note describes a streamlined metallographic preparation workflow using LECO’s CAMEO Magnetic Disc System and the GPX 200 Grinder/Polisher. The goal is to achieve a high‐quality surface finish suitable for microhardness profiling of case‐hardened steel samples, reducing traditional multi‐step procedures to three key steps.

Methodology and Instrumentation

A three‐step polishing sequence replaces conventional multi‐disc grinding and polishing:

• Step 1 – Grinding on Platinum 1 disc (water, 2 minutes, 35 psi, 75 rpm, counter‐clockwise head, 175 rpm wheel)
• Step 2 – Pre‐polishing on Silver 6µ/ME disc (water, 2 minutes, 35 psi, 75 rpm, counter‐clockwise head, 175 rpm wheel)
• Step 3 – Final polishing on UltraSilk 3µ/ME disc (water, 3 minutes, 45 psi, 100 rpm, counter‐clockwise head, 200 rpm wheel)

Instrumentation:

• LECO CAMEO Magnetic Disc System
• LECO GPX 200 Grinder/Polisher with fixed sample holder
• Microhardness tester (Vickers or Knoop, ≥ 500× magnification)

Main Results and Discussion

The three‐step sequence successfully eliminated large scratches after grinding and reduced fine scratches after pre‐polish, yielding a mirror‐like finish with distinct Vickers impression corners. Accurate measurement of diagonals became possible, ensuring reliable microhardness profiling. This procedure maintained sample integrity and supported automated hardness testing.

Benefits and Practical Applications

• Reduced preparation time and fewer consumables
• Consistent, reproducible surface finishes
• Enhanced accuracy in microhardness measurements
• Compatibility with automated testing platforms
• Applicability to quality control and research laboratories

Future Trends and Applications

Advances may include integration of automated polishing cycles, development of novel abrasive materials for finer finishes, and coupling with AI‐driven image analysis to further streamline case depth assessment. Emerging in‐line hardness monitoring and real‐time process feedback represent potential extensions.

Conclusion

The CAMEO three‐step metallographic procedure delivers a robust, efficient approach to prepare case‐hardened steel for microhardness analysis. By simplifying traditional workflows, laboratories can achieve high‐quality finishes and precise depth measurements with reduced labor and resource consumption.