Metallographic Preparation Procedure for Fastener Samples

Metallographic Preparation Procedure for Fastener Samples

Fasteners are a widely used class of mechanical components designed for securing and connecting joints. They are extensively applied across various fields, including machinery, equipment, vehicles, vessels, railways, bridges, buildings, structures, tools, instruments, apparatus, and consumer goods.

For the metallographic evaluation of small fasteners, sectioning can be performed slightly off the central axis of the thread, followed by mechanical grinding close to the central axis after pre-mounting. Alternatively, a conventional abrasive cutter equipped with a thin cutting disc can be used for longitudinal sectioning, or precision sectioning equipment can be employed to minimize kerf loss, allowing the cut to be made closer to the central axis of the fastener.

Hot compression mounting of fastener samples is generally recommended prior to subsequent grinding and polishing. Hot mounting ensures excellent repeatability. The selection of mounting resin typically requires good edge retention properties combined with high Shore hardness, which ensures a flatter sample surface during the subsequent grinding and polishing stages.

Following mounting, two preparation methods can be adopted based on the material type:

* Ferrous Metals: Diamond grinding discs or abrasive papers.

* Non-Ferrous Metals: Abrasive papers.

The following table outlines a 4-step preparation method for aluminum alloy fasteners, offering a simple and highly efficient solution for sample preparation.

Polished Surface at 200X