High Carbon Steel / Heat Treated Steel - Metallographic Sample Preparation

Preparing high carbon steel for metallographic analysis is simple when using OnPoint Abrasives' consumables and procedures. We have provided a step by step process for metallographic sample preparation of high carbon steel below.

Sectioning: Section specimen with ToughSec abrasive blade or multi-purpose diamond blade.

Mounting: For best results, compression mount specimen using EpoMount epoxy powder. The high hardness of the epoxy will provide superior edge retention and promote flatness across the entire surface of the mount. 

For samples that require cold mounting, we recommend using EpoPro liquid epoxy system. Employing a vacuum impregnation chamber while conducting the cold mounting procedure effectively eradicates undesired air bubbles from the epoxy material, enabling its penetration into the intricate geometries of your specimen. This may not be required in all instances,

Grinding and Polishing: OnPoint's guidelines for grinding and polishing serve as a reference for preparing samples for metallographic analysis. Our steel alloy procedure is specifically designed for employment on an automated polisher featuring Central Force capability. This procedure uses a contra directional pattern between the working wheel and specimen holder.

When using polishers that possess exclusively Individual Force capability or when opting for manual polishing, the operator should commence the procedure from step number 2. Adjustments are also necessary when using Individual Force or manual polishing. We advise adopting a complimentary directional pattern. For Steps 1 and 2, maintain an RPM of 200/base and 150/head. For steps 3 and 4, reduce the RPM to 150/base and 100/head. It might be necessary to extend polishing durations for all steps.

In this section, we've provided two methods for preparing your steel specimen for analysis, Traditional Method and Advanced Method.

The Traditional Method uses a series of Silicon Carbide grinding papers to first planarize and grind the surface to around 15 micron (600 grit), before moving to polishing steps using suspensions and cloths. This method is effective for general purpose metallography, although it can introduce some relief, or rounding of the specimen's edge.

Note: Clean specimen by gently scrubbing the surface with a cotton ball under running water. Repeat until all alumina is removed. Use of an ultrasonic cleaner is highly recommended for samples with high porosity content or intricate geometries.

Our Advanced Method uses fewer steps of SiC grinding paper to initially planarize the mounted specimen. This is followed by a series of "loose" abrasive polishing steps that utilize diamond and alumina suspensions along with polishing cloths. The less aggressive nature of this method preserves the specimen's edge and produces ultra-flat results. This can be critical for case depth analysis or for samples that are examined near the specimen's edge. It is viewed by many that the "advanced" methods of preparation offer superior results and higher consistency when compared to traditional methods.

 *For the final step, alternate between the alumina and ProPrep colloidal silica at 20 second intervals. Finish with a large dose of alumina when 0:30 seconds remain. 

Clean specimen by gently scrubbing the surface with a cotton ball under running water. Repeat until all alumina is removed. Use of an ultrasonic cleaner is highly recommended for samples with high porosity content or intricate geometries.