Metals
Molybdenum Grades, Forms & Specifications: A Buyer's Guide
Centura Insights · 2026-03-11
Ordering molybdenum is easy to get wrong because the same metal is sold in very different forms, each with its own grade language - ferromolybdenum is graded by Mo percentage, powder by purity and particle size, and mill products by purity, dimensions, and surface. This buyer's guide demystifies the specifications so you can write a clean purchase order.
Across all forms, the single most important document is the certificate confirming chemistry: a mill test certificate (MTC) for alloys and a certificate of analysis (CoA) for metal and chemical products.
Ferromolybdenum grades
Ferromolybdenum (FeMo) is graded by contained molybdenum and by maximum impurity limits. Low carbon, phosphorus, and sulphur matter for clean steelmaking.
| Parameter | Typical value |
|---|---|
| Molybdenum (Mo) | 60% / 65% / 70% min |
| Carbon (C) | 0.10% max |
| Phosphorus (P) | 0.05% max |
| Sulphur (S) | 0.10% max |
| Sizing | 10-50 mm lumps (custom) |
Molybdenum metal powder
Powder is specified by purity, particle size (often as Fisher Sub-Sieve Size, FSSS), oxygen content, and apparent density. These drive how the powder presses, sinters, or sprays.
- Purity: typically 99.95% Mo
- Particle size (FSSS): commonly 3-6 microns, customisable
- Oxygen content: low oxygen for clean sintering
- Apparent density: matched to your process
Mill products: bar, plate, sheet, and wire
Wrought molybdenum mill products are specified by purity, dimensions and tolerances, surface condition, and the applicable standard (for example ASTM B386 for plate/sheet). State whether you need pure molybdenum or an alloy such as TZM.
| Product | Key specs to state | Common standard |
|---|---|---|
| Bar / rod | Diameter, length, surface | ASTM B387 |
| Plate / sheet | Thickness, width, flatness, surface | ASTM B386 |
| Wire | Diameter, surface, temper | Customer spec |
| Sputtering target | Purity, density, dimensions, bonding | Customer spec |
Purity and why it matters
Higher purity (99.95% to 99.99%) is essential in electronics, solar, and semiconductor applications where trace contamination affects film quality. For steelmaking, the cost-effective route is ferromolybdenum or technical oxide rather than high-purity metal.
Writing a clean purchase order
Specify the form, grade/purity, dimensions or sizing, surface or particle size, quantity, packaging, required certificates, destination, and timeline. The more precise the PO, the faster and more accurate the quotation. Browse our molybdenum product range or request a quote with your specification.
Frequently Asked Questions
What purity is standard for molybdenum metal products?
Most molybdenum mill products are 99.95% pure, while sputtering targets for electronics are available up to 99.99%. Steelmaking generally uses ferromolybdenum or technical oxide rather than high-purity metal.
What standards apply to molybdenum mill products?
ASTM B386 covers molybdenum plate and sheet, ASTM B387 covers bar and rod, and targets and wire are usually made to a customer specification.
What information do you need to quote molybdenum?
Form, grade or purity, dimensions or sizing, surface or particle size, quantity, packaging, certificates required, destination, and timeline.
Key Takeaways
Apply these insights to improve sourcing execution, reduce risk, and deliver consistent supply outcomes.
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