RAYCHIN LIMITED

Tantalum Shoulder Bolts – Complete Product Range

Critical Applications of Tantalum Shoulder Bolts

International Standards & Global Designations – Tantalum Shoulder Bolt Materials

RAYCHIN LIMITED manufactures Tantalum shoulder bolts from material conforming to the most widely used national and international specifications. All material is traceable to the mill.

Chemical Composition (Weight %) – Tantalum Alloys for Shoulder Bolts

Our Tantalum shoulder bolts are produced from material conforming to the limits of applicable ASTM, AMS, and ASME standards. High‑purity grades available up to 99.99% (4N).

Pure Tantalum (UNS R05200 / R05400) – ASTM B365 / F560

Tantalum-Tungsten Alloys (Ta2.5W / Ta10W) – ASTM B365

Metallurgical note: Tantalum is a body-centered cubic (BCC) refractory metal with a melting point of 2996°C, second only to tungsten and rhenium. It is highly ductile and can be cold worked extensively without intermediate annealing. Tantalum derives its exceptional corrosion resistance from a stable, adherent pentoxide (Ta₂O₅) film that forms spontaneously in air or oxidizing media. This oxide film is self‑healing if damaged and protects the underlying metal from attack by all common acids except hydrofluoric acid. Tantalum is also completely biocompatible and non‑toxic, making it ideal for medical implants. Tungsten alloying additions (2.5% or 10%) increase strength, creep resistance, and recrystallization temperature while maintaining good fabricability. The density of tantalum (16.6 g/cm³) is approximately twice that of steel, providing substantial mass in compact designs. For shoulder bolts, the precision ground shoulder (typically h7 or ±0.0005" tolerance) acts as a bearing surface and requires careful machining to maintain dimensional accuracy.

Complete Mechanical & Physical Properties – Tantalum Alloys for Shoulder Bolts (MPa / ksi)

Tantalum shoulder bolts are supplied in appropriate conditions (annealed, stress relieved, or Ta-10W) per ASTM B365 and customer specifications. Data represent typical values based on industry standards.

Pure Tantalum (R05200) – Mechanical Properties

Tantalum Alloys – Mechanical Properties

High‑Temperature Mechanical Properties – Pure Tantalum (representative)

Physical Properties – Tantalum

High‑Temperature Performance of Tantalum Shoulder Bolts

Tantalum is one of the most refractory metals, with a melting point of 2996°C (5425°F), exceeded only by tungsten and rhenium. This exceptional high‑temperature capability makes tantalum shoulder bolts ideal for extreme thermal environments. Tantalum maintains useful mechanical properties at temperatures exceeding 2000°C in vacuum or inert atmospheres. It exhibits excellent creep resistance and thermal stability. Tantalum‑tungsten alloys (Ta-10W) offer significantly higher strength at elevated temperatures and are used for shoulder bolts in high‑temperature furnaces, rocket engines, and jet propulsion systems. Tantalum's low vapor pressure ensures no contamination of vacuum environments, making it essential for vacuum furnace hot zones and semiconductor processing equipment. The coefficient of thermal expansion (6.5 × 10⁻⁶/K) is low and matches well with many ceramic and refractory materials, reducing thermal stress in high‑temperature assemblies. Tantalum retains good ductility even after exposure to high temperatures, unlike some other refractory metals.

Elevated Temperature Capabilities

*Note: Tantalum oxidizes rapidly in air above 260-300°C. For high‑temperature air applications, protective coatings are required. Tantalum is primarily used in vacuum, inert gas, or reducing atmospheres at elevated temperatures.

Exceptional Corrosion Resistance of Tantalum Shoulder Bolts

Tantalum is renowned for its outstanding corrosion resistance, approaching that of glass in many aggressive media. It is virtually immune to attack by most acids and chemical compounds below 150°C. The protective Ta₂O₅ oxide film (thickness 2-5 nm) is stable, adherent, and self‑healing if damaged. Tantalum's corrosion resistance often exceeds that of noble metals like platinum at a fraction of the cost. Tantalum shoulder bolts provide reliable pivoting and fastening in the most aggressive chemical environments.

• Hydrochloric Acid: Completely resistant to hydrochloric acid at all concentrations and temperatures up to 110°C (boiling). At 150°C, corrosion rate is only 0.0004 mm/year.
• Sulfuric Acid: Excellent resistance up to 150°C at all concentrations. At 175°C in concentrated sulfuric acid, corrosion rate is 0.0004 mm/year. At 200°C, 0.006 mm/year. At 250°C, 0.116 mm/year.
• Nitric Acid: Completely resistant at all concentrations and temperatures up to boiling.
• Phosphoric Acid: Excellent resistance up to 150°C. At 250°C in 85% phosphoric acid, corrosion rate approximately 20 mm/year.
• Aqua Regia: Completely resistant at all temperatures up to boiling.
• Organic Acids: Completely resistant to all organic acids, including acetic, formic, and citric acids.
• Halogens: Resistant to chlorine, bromine, and iodine up to 150°C in dry conditions. At 250°C, dry chlorine does not attack tantalum. Moist halogens above 150°C can attack.
• Alkalis: Attacked by strong alkalis. In 40% NaOH at 110°C, rapid dissolution.
• Hydrofluoric Acid: Rapidly dissolved by hydrofluoric acid (HF) and HF-containing mixtures – the primary acid that attacks tantalum.
• Molten Metals: Resistant to many molten metals including Li, Na, K, Mg, and U up to 1000°C.
• Salt Spray: Excellent resistance to marine environments; no measurable corrosion after years of immersion.
• Hydrogen Embrittlement: Standard tantalum is susceptible to hydrogen embrittlement in strongly reducing acid environments. Special alloys (ULTRA 76 Plus) reduce hydrogen pickup by up to 100 times.

Manufacturing Standards – Tantalum Shoulder Bolts

All Tantalum shoulder bolts are manufactured and tested to meet the following standards:

We offer surface finishes: plain (as‑machined), passivated, electropolished. The shoulder is precision ground to tolerances of ±0.0005" (inch) or h7 (metric). Tantalum shoulder bolts can be supplied with certified material traceability, dimensional inspection reports, and mechanical test certificates. Our manufacturing processes include CNC turning, centerless grinding, thread rolling, and precision shoulder grinding. We specialize in custom configurations including non‑standard shoulder diameters, extra long shoulders, special head styles, and proprietary drive systems. Cleanroom packaging available for medical and semiconductor applications. All shoulder bolts supplied with EN 10204 Type 3.1 or 3.2 certification. ISO 9001:2015 and AS9100D certified quality management system.