Most fastener suppliers buy bar stock. We melt our own superalloys.
90% of fastener suppliers purchase bar stock from trading companies, with zero visibility into material origin and no control over inclusion content, gas levels, or grain size. Below are measured values from our production records.
| Property | Purchased Bar Stock | VIM+ESR/VAR Self-Melted |
|---|---|---|
| Oxygen (ppm) | 30-80 ppm | <10 ppm |
| Nitrogen (ppm) | 50-150 ppm | <30 ppm |
| Inclusion Content | ASTM E45 >=3.0 | ASTM E45 <=1.5 |
| Grain Size | ASTM 3-5 (coarse) | ASTM 8+ (fine, uniform) |
| Traceability | Mill cert only (opaque) | Full furnace-to-bolt traceability |
Each melt stage eliminates a specific class of metallurgical defect. Skip one, and the defect survives to the finished bolt.
Raw alloying elements are melted under high vacuum. Dissolved gases (O2, N2, H2) are drawn out, and precise chemistry control is achieved. The result is a clean master ingot with uniform composition, the essential first step no bar-stock supplier can guarantee.
The VIM ingot is remelted through a pool of reactive molten slag. Non-metallic inclusions are absorbed by the slag, sulfur is reduced, and directional solidification produces a refined, segregation-free grain structure. This step eliminates the inclusion clusters that cause premature fastener failure.
The ESR ingot undergoes a final melt under extreme vacuum via a controlled electric arc. Remaining trace gases drop to single-digit ppm levels (O2 <10 ppm). The result: ultra-clean, fine-grained superalloy bar stock with full furnace-to-bolt traceability, ready for hot forging.
Get a technical quote for your custom high temp bolts within 24 hours. Our engineers speak your language, so send us your drawing and we'll spec the alloy.