Overview
This document details the chemical composition standards for niobium and niobium alloys as defined by ASTM B391, B392, B393, B394. It covers ingots and finished products, ensuring material consistency for critical applications in aerospace, electronics, and nuclear industries.
Chemical Requirements for Ingots（Maximum Weight %）
| Element | Type 1 Reactor Grade Unalloyed Niobium R04200 | Type 2 Commercial Grade Unalloyed Niobium R04210 | Type 3 Reactor Grade Niobium 1% Zirconium R04251 | Type 4 Commercial Grade Niobium 1% Zirconium R04261 |
| Carbon | 0.01 | 0.01 | 0.01 | 0.01 |
| Nitrogen | 0.01 | 0.01 | 0.01 | 0.01 |
| Oxygen | 0.015 | 0.025 | 0.015 | 0.025 |
| Hydrogen | 0.0015 | 0.0016 | 0.0015 | 0.0016 |
| Zirconium | 0.02 | 0.02 | 0.8 to 1.2 | 0.8 to 1.2 |
| Tantalum | 0.01 | 0.02 | 0.1 | 0.5 |
| Iron | 0.005 | 0.01 | 0.005 | 0.01 |
| Silicon | 0.005 | 0.005 | 0.005 | 0.005 |
| Tungsten | 0.03 | 0.05 | 0.03 | 0.05 |
| Nickel | 0.005 | 0.005 | 0.005 | 0.005 |
| Molybdenum | 0.010 | 0.10 | 0.10 | 0.050 |
| Hafnium | 0.02 | 0.02 | 0.02 | 0.02 |
| When Specified | ||||
| Boron | 0.0002 | – | 0.0002 | – |
| Aluminum | 0.002 | 0.005 | 0.002 | 0.005 |
| Beryllium | 0.005 | – | 0.005 | – |
| Chromium | 0.002 | – | 0.002 | – |
| Cobalt | 0.002 | – | 0.002 | – |
Additional Requirements for Finished Products（Maximum, ppm）
| Element | Type 1 Reactor Grade Unalloyed Niobium R04200 | Type 2 Commercial Grade Unalloyed Niobium R04210 | Type 3 Reactor Grade Niobium 1% Zirconium R04251 | Type 4 Commercial Grade Niobium 1% Zirconium R04261 |
| Oxygen | 250 | 400 | 250 | 400 |
| Carbon | 100 | 150 | 100 | 150 |
| Nitrogen | 100 | 100 | 100 | 100 |
| Hydrogen | 15 | 15 | 15 | 15 |
Key Significance
- Standard Compliance: Aligns with ASTM B391 – B394, ensuring material quality for regulated industries (nuclear, aerospace).
- Alloy Customization: Grades like Type 3 (Nb – 1% Zr) support high – performance applications (nuclear reactors, high – temp structures).
- Impurity Control: Strict limits on O, C, N, H ensure niobium performance in critical environments (e.g., nuclear reactors, aerospace engines).
Application Guidance
- Nuclear Industry: Type 1/3 (reactor – grade) niobium suits nuclear components (cladding, structural parts) due to low impurity levels.
- Aerospace: Type 2/4 (commercial – grade) supports high – temp aerospace parts (engines, frames) with balanced strength and purity.
- Quality Assurance: Certifiable to ASTM standards, providing traceability for safety – critical projects.
Document Value
Essential for manufacturers, suppliers, and engineers to verify niobium alloy chemistry, ensuring product reliability and regulatory compliance. Use this to select materials, validate specifications, and support technical documentation.