Bulk Analysis of Fasteners Using 2 mm Lamp (Rivet, Screw and Bolt)

Importance of the Topic

Fasteners such as rivets, screws and bolts are critical in virtually all manufactured goods. Their long-term mechanical performance and safety depend on precise chemical composition, making routine bulk elemental analysis essential in quality control and materials research.

Study Objectives and Overview

This note describes the application of a 2 mm lamp in a LECO GDS500A glow discharge spectrometer for rapid, accurate compositional analysis of small-diameter fasteners. The aim is to demonstrate analytical repeatability, precision and practical workflow for aluminum, carbon steel and stainless steel samples down to 2.5 mm in diameter.

Methodology and Instrumentation

The GDS500A uses a CCD-based glow discharge source to sputter material uniformly from the sample surface. Analysis occurs away from the surface, minimizing metallurgical history effects. Key steps:

• Section or flatten fastener shafts to maximize exposed area.
• Mount ferrous samples in copper-filled diallyl phthalate; finish with 120-grit zirconia belt and 320-grit polish for nonferrous materials.
• Employ the 2 mm lamp kit to bridge the anode–cathode gap for small samples.
• Use factory or customer-provided calibration standards (CRMs and RMs) from NIST, Alcoa, MBH, etc., with drift correction via homogeneous setup standards.
• Perform multi-burn routines: three analyses in 90 s via continuous sputtering and ‘analyze all in one spot’ software option.

Key Results and Discussion

Analysis of a 4 mm aluminum rivet yielded major Al content (~95.4 %) with trace Cr, Cu, Fe, Mg, Mn, Si and Zn. Relative standard deviations (RSD) for most elements were below 3 %, reaching <1 % for Cr and Cu. A 4 mm carbon steel screw showed Fe ~97.3 %, C ~0.39 % and other alloying elements with RSDs under 6 %. A 6 mm stainless bolt exhibited Fe ~55 %, Ni ~24.5 %, Cr ~14.6 % and minor elements including Ti and Mo, with RSDs below 1 % for major constituents. These data confirm excellent repeatability and linear calibration across wide concentration ranges.

Benefits and Practical Applications

The GDS500A with a 2 mm lamp kit enables high-throughput, non-destructive bulk analysis of small fasteners. Key advantages include minimal sample preparation, linear response for multiple elements, low spectral interferences and robust drift control. This approach supports in-line QA/QC in aerospace, automotive and construction industries.

Future Trends and Potential Applications

Trends include expanding micro-glow discharge to sub-millimeter components, integrating automated sample handling and coupling with advanced data analytics for predictive maintenance. Broader adoption in additive manufacturing and microfabrication quality control is anticipated.

Conclusion

The 2 mm lamp on the LECO GDS500A delivers precise, reproducible bulk elemental analysis of fasteners as small as 2.5 mm. Its speed, stability and broad dynamic range make it a powerful tool for routine materials verification in demanding industrial environments.

References

Preparation of Specimens for Bulk Analysis Using LECO GDS (209-076-031) application note. LECO Corporation.