RAYCHIN LIMITED

Tungsten Hex Nuts – Comprehensive Product Range

International Standards & Global Designations – Tungsten Hex Nuts

RAYCHIN LIMITED manufactures tungsten hex nuts from vacuum arc melted (VAR) or powder metallurgy processed material conforming to the most widely used national and international specifications. All material is traceable to the mill with complete certifications.

Chemical Composition (Weight %) – Tungsten & Tungsten Alloys

Our tungsten hex nuts are produced from vacuum arc melted (VAR) or powder metallurgy processed material conforming to the limits of applicable ASTM and AMS specifications.

Pure Tungsten (ASTM B760)

Tungsten Heavy Alloys (ASTM B777)

Metallurgical note: Tungsten is a refractory metal with the highest melting point of all metals (3422°C). Pure tungsten exhibits a body-centered cubic crystal structure and exceptional high-temperature strength, but is difficult to machine due to its brittleness at room temperature. Tungsten heavy alloys are produced by liquid phase sintering of tungsten powder with nickel-iron or nickel-copper binders, creating a composite microstructure of tungsten grains embedded in a ductile matrix. This structure provides improved machinability while maintaining high density. The nickel-iron binder system offers higher strength and ductility, while nickel-copper binder provides non-magnetic properties. Higher tungsten content (Class 4 > Class 1) increases density but reduces ductility and machinability. All tungsten alloys are susceptible to oxidation above 500°C and require protective atmospheres or coatings for high-temperature service in air.

Complete Mechanical & Physical Properties – Tungsten Alloys (MPa / ksi)

Tungsten hex nuts are supplied in sintered, annealed, or stress-relieved condition per applicable ASTM specifications. Data represent typical values based on industry standards.

Mechanical Properties – Tungsten Heavy Alloys (ASTM B777)

Pure Tungsten – Mechanical Properties

Data per ASTM B777 and Goodfellow specifications.

High-Temperature Mechanical Properties – Class 3 (95% W) Alloy

High-temperature testing in vacuum or inert atmosphere. Mechanical properties degrade above 800°C due to microstructural changes in the binder phase.

Physical Properties – Tungsten Alloys

Pure tungsten has the highest density of all engineering metals – more than twice that of steel.

High‑Temperature Performance of Tungsten Hex Nuts

Tungsten is the refractory metal with the highest melting point (3422°C) and exceptional high-temperature strength and stability in vacuum or inert atmospheres. Pure tungsten maintains useful mechanical properties up to 2800°C (5072°F) in non-oxidizing environments, making it suitable for extreme temperature applications in rocket engines, plasma-facing components, and high-temperature furnaces. Tungsten heavy alloys have lower maximum service temperatures (typically 800-1000°C) due to the presence of lower-melting binder phases (Ni-Fe, Ni-Cu) which begin to soften and weaken at elevated temperatures.

Oxidation Behavior

Tungsten begins to oxidize rapidly at temperatures above 500°C in air, forming volatile tungsten trioxide (WO₃). This leads to rapid material loss and catastrophic failure. Therefore, tungsten hex nuts are not suitable for high-temperature applications in air without protective coatings (such as MoSi₂, SiC, or Ir). In vacuum or inert gas atmospheres (argon, helium, hydrogen), tungsten maintains its strength and integrity to very high temperatures.

Elevated Temperature Capabilities

Corrosion Resistance of Tungsten Hex Nuts

Tungsten has limited corrosion resistance in most environments due to its susceptibility to oxidation. However, in specific conditions, tungsten offers unique advantages.

Chemical Resistance

• Oxidation Resistance: Poor above 500°C in air – requires protective atmosphere or coating.
• Acid Resistance: Tungsten is slowly attacked by most mineral acids at room temperature, and rapidly dissolved by a mixture of hydrofluoric and nitric acids.
• Alkali Resistance: Good resistance to alkalis at room temperature.
• Liquid Metal Compatibility: Excellent resistance to attack by many molten metals (Li, Na, K, Mg, Zn, Ag) – valuable for nuclear and metallurgical applications.
• Hydrogen Compatibility: Fully compatible with hydrogen up to very high temperatures – used in hydrogen furnace applications.
• Nitrogen Reaction: Reacts with nitrogen above 1500°C to form nitrides, causing embrittlement – not recommended for high-temperature nitrogen atmospheres.
• Corrosion in Aqueous Environments: Tungsten heavy alloys may suffer galvanic corrosion between tungsten grains and the binder phase in aqueous electrolytes – not recommended for wet chemical environments without protective measures.

Manufacturing Standards – Tungsten Hex Nuts

All tungsten hex nuts are manufactured and tested to meet the following standards:

We offer surface finishes: as-sintered, ground, polished, or coated with oxidation-resistant coatings (MoSi₂, SiC) for high-temperature air service. Controlled sintering and heat treatment processes per ASTM specifications ensure consistent mechanical properties. Specialized CNC grinding and tapping for accurate nut geometry – tungsten alloys require diamond tooling and specialized techniques due to their extreme hardness and brittleness. Class 2B/6H thread fit. 100% inspection available including dimensional inspection, density testing, and non-destructive examination. Full traceability and material test reports (MTR) with mill certifications available. AS9100 and ISO 9001:2015 certified quality management. ISO 13485 certified for medical applications with cleanroom packaging available. Build-to-print specials to customer specifications are available.