Tantalum Fasteners

Tantalum Button Head Cap Screws

Tantalum Button Head Cap Screws are best known for its unmatched corrosion resistance and chemical inertness. Tantalum Button Head Cap Screws have a similar corrosion resistance to that of glass, but all of the typical mechanical and electrical properties of a metal.
Tantalum Button Head Cap Screws are also extremely stable at high temperatures, since tantalum has a melting point around 3000°C. High temperature applications require vaccum or inert gas since tantalum may embrittle when used in oxygen rich environments above 250°C. Tantalum Button Head Cap Screws are also one of the most bio-compatible metals available and is also radio-opaque due to its high density (16.68 g/cm3).
All tantalum Button Head Cap Screws are available in commercially pure tantalum and tantalum 2.5% tungsten (Ta-2.5%W).
  • Tantalum Button Head Cap Screws
  • Tantalum Button Head Cap Screws
  • Tantalum Button Head Cap Screws
  • Tantalum Button Head Cap Screws
  • Tantalum Button Head Cap Screws
  • Tantalum Button Head Cap Screws
  • Tantalum Button Head Cap Screws
  • Tantalum Button Head Cap Screws
  • Tantalum Button Head Cap Screws
  • Tantalum Button Head Cap Screws

RAYCHIN SPECIALTY METALS FASTENERS: BOLTS, NUTS, SCREWS, WASHERS, STUDS, THREADED RODS, U-BOLT, J-BOLTS

STANDARD AND CUSTOMIZED, SMALL BATCH AND LARGE BATCH, IMPERIAL AND METRIC


  • Immune to numerous acids and chemicals 

  • Better corrosion resistance than nickel alloys, titanium or zirconium

  • High strength and stiffness in vacuum and inert gas up to 2000°C (3600°F)

  • Can become brittle when used in oxygen above 300°C

  • High purity and biocompatibilty

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Tantalum Button Head Cap Screws: Extreme Corrosion Resistant Fasteners for Chemical, Medical & Aerospace Applications

Commercially Pure Tantalum (UNS R05200) | Ta-2.5%W (UNS R05252) | ASTM B708 | ASTM B521 | AMS 7849 | Refractory Metal

RAYCHIN LIMITED is a leading manufacturer of Tantalum Button Head Cap Screws – precision fasteners produced from refractory tantalum metal, delivering unmatched corrosion resistance, biocompatibility, and reliable performance in the most demanding chemical processing, medical, and semiconductor applications. Button head cap screws combine a low-profile, wide-bearing head with hex socket drive, providing excellent clamping force in confined spaces where counter-boring is impractical. Tantalum is a refractory metal with a melting point of 2996°C (5425°F) and corrosion resistance similar to glass – immune to virtually all acids and chemicals except hydrofluoric acid and hot concentrated alkalis. Our product line includes commercially pure tantalum button head screws and tantalum 2.5% tungsten alloy button head screws – all manufactured to the highest precision standards. Tantalum grades conform to UNS R05200 (electron-beam or vacuum-arc melted unalloyed tantalum) and UNS R05252 (tantalum 2.5% tungsten alloy) per ASTM B708 and ASTM B521 specifications. Our portfolio includes all standard and custom configurations manufactured to NAS, AN, MS, ANSI, ASTM, ASME, SAE, API, NACE, ISO, DIN and KS standards. Whether you require tantalum button head cap screws for chemical reactor linings, medical implants, or high-temperature vacuum furnaces, RAYCHIN delivers precision, quality, and full traceability. All mechanical properties are presented in MPa and ksi (kilopound per square inch).

tantalum button head cap screwstantalum button head screwstantalum socket screwstantalum fastenersUNS R05200 screwsUNS R05252 screwsta-2.5w screwstantalum alloy fastenerscorrosion resistant screwsrefractory metal fastenerschemical processing screwsbiocompatible screwsASTM B708 tantalumtantalum hex socket screws

Tantalum Button Head Cap Screws – Design & Configurations

Low-Profile Button Head Design

Tantalum button head cap screws feature a low-profile, dome-shaped head with a wide bearing surface, providing excellent clamping force while maintaining a clean, finished appearance. The button head design is ideal for applications where clearance is limited or where counter-boring is not feasible. Available with hex socket drive (Allen) for positive engagement and high torque transmission. Head dimensions conform to ASME B18.3 (inch series) and ISO 7380 (metric series). Diameters from #0 to 1/2" (M1.6 to M12).

Commercially Pure Tantalum (R05200)

Commercially pure tantalum button head screws are produced from UNS R05200 material, meeting ASTM B708 and ASTM B521 specifications. This grade offers exceptional corrosion resistance – virtually immune to attack by most acids including hydrochloric, nitric, sulfuric (up to 175°C), and aqua regia. Purity exceeds 99.95% tantalum with minimal interstitial elements. Used in chemical processing equipment, pharmaceutical reactors, and medical implants requiring maximum biocompatibility.

Tantalum 2.5% Tungsten (R05252)

Tantalum 2.5% tungsten alloy button head screws provide enhanced strength while maintaining tantalum's exceptional corrosion resistance. The addition of tungsten (2.5%) increases tensile and yield strength by approximately 30% compared to pure tantalum, making these screws ideal for applications requiring higher mechanical loads in corrosive environments. Conforms to UNS R05252, ASTM B708, and ASTM B521 specifications. Preferred for chemical processing and aerospace applications.

Hex Socket Drive

Tantalum button head cap screws feature precision hexagon socket drives per ASME B18.3 (inch series) and ISO 7380 / DIN 912 (metric series). The internal hex drive allows for high tightening torques and secure installation in confined spaces where external wrenching is impractical. Available with standard hex sizes and tamper-resistant configurations for security applications. Drive sockets are precision broached to ensure proper tool engagement and torque transmission.

Aerospace & Medical Standards

Our tantalum button head screws meet applicable sections of NAS1352 (socket head screws) and AMS 7849 (tantalum sheet, strip, plate). Full compliance with ASTM B708 (tantalum plate, sheet, strip), ASTM B521 (tantalum seamless tube), and ASTM F560 (tantalum for surgical implants). Tantalum's biocompatibility and radio-opacity make it ideal for medical implant applications including X-ray markers and orthopedic devices.

Custom & Non-Standard Screws

Need special head configurations, proprietary drives, non‑standard lengths, or unique thread forms? RAYCHIN engineers design and produce custom tantalum button head cap screws to your exact specifications – any condition (annealed, stress-relieved), with full material traceability. Prototype to production volumes supported. Cleanroom wash and packaging available for medical and semiconductor applications.

Critical Applications of Tantalum Button Head Cap Screws

Chemical Processing

Tantalum button head screws are extensively used in chemical processing equipment including reactor linings, heat exchangers, distillation columns, and piping systems handling corrosive media. Tantalum exhibits virtually zero corrosion rate in most acids including hydrochloric, nitric, sulfuric (up to 175°C), phosphoric, and organic acids. Used in pharmaceutical manufacturing, fine chemical production, and specialty chemical processing where material purity must be maintained.

Medical & Implantable Devices

Tantalum button head screws are qualified for medical implant applications due to tantalum's exceptional biocompatibility, corrosion resistance in body fluids, and radio-opacity. Tantalum is used for X-ray markers in polyethylene components, orthopedic implants, surgical instruments, and dental devices. The material is non-toxic and does not elicit adverse tissue reactions, making it ideal for long-term implantation. Meets ASTM F560 requirements for surgical implant applications.

Semiconductor Manufacturing

Tantalum button head screws in semiconductor processing equipment including wafer handling systems, CVD reactors, and etch chambers. Tantalum's resistance to halogenated gases and plasma environments, combined with high purity (low interstitial elements), prevents contamination of sensitive semiconductor materials. Used in chamber hardware, gas distribution systems, and wafer fixturing where corrosion resistance and purity are critical.

Aerospace & Defense

Tantalum button head screws in aerospace applications including rocket engine components, high-temperature fasteners, and radiation shielding. Tantalum maintains useful mechanical properties in vacuum and inert gas up to 2000°C (3632°F), making it suitable for extreme temperature applications. Used in propulsion systems, nozzle assemblies, and heat shields where high melting point and oxidation resistance (in non-oxidizing environments) are essential.

Pharmaceutical & Bioprocessing

Tantalum button head screws in pharmaceutical manufacturing equipment including bioreactors, fermenters, and purification systems. Tantalum's corrosion resistance ensures no metal contamination of sensitive pharmaceutical products. The material's smooth surface finish and cleanability meet cGMP requirements for pharmaceutical processing equipment. Used in vessel internals, agitator assemblies, and sampling ports.

High-Temperature Vacuum Furnaces

Tantalum button head screws in vacuum furnace hot zones, heating elements, and heat shields. Tantalum maintains strength at elevated temperatures in vacuum or inert gas atmospheres, with recrystallization temperature above 1200°C. Used in sintering furnaces, heat treating equipment, and crystal growing furnaces requiring refractory metal fasteners that maintain integrity at extreme temperatures.

International Standards & Global Designations – Tantalum Button Head Cap Screws

RAYCHIN LIMITED manufactures tantalum button head cap screws from electron-beam melted or vacuum-arc melted material conforming to the most widely used national and international specifications. All material is traceable to the mill.

GradeDesignationStandard / Specification
Commercially Pure TantalumUNS R05200Unified Numbering System – electron-beam or vacuum-arc melted
UNS R05400Unified Numbering System – powder metallurgy consolidation
ASTM B708Standard specification for tantalum plate, sheet, and strip
ASTM B521Standard specification for tantalum seamless tube
ASTM F560Standard specification for unalloyed tantalum for surgical implant applications
AMS 7849Aerospace material specification for tantalum sheet, strip, and plate
Tantalum 2.5% TungstenUNS R05252Unified Numbering System – Ta-2.5%W alloy
ASTM B708Standard specification for tantalum alloy plate, sheet, and strip
ASTM B521Standard specification for tantalum alloy seamless tube
TaW2.5Common designation in European and Asian markets
UNS R05200 UNS R05252 ASTM B708 ASTM B521 ASTM F560 AMS 7849 Ta-2.5W

Chemical Composition (Weight %) – Tantalum Grades

Our tantalum button head cap screws are produced from electron-beam melted (EB) or vacuum-arc remelted (VAR) material conforming to the limits of applicable ASTM specifications.

Commercially Pure Tantalum – UNS R05200 / R05400

ElementMax % (R05200)Max % (R05400)
Tantalum (Ta)Balance (99.95% min)
Carbon (C)0.0100.010
Oxygen (O)0.0150.030
Nitrogen (N)0.0100.010
Hydrogen (H)0.00150.0015
Niobium (Nb)0.100.10
Iron (Fe)0.0100.010
Titanium (Ti)0.0100.010
Tungsten (W)0.0500.050
Molybdenum (Mo)0.0200.020
Silicon (Si)0.0050.005
Nickel (Ni)0.0100.010

Tantalum 2.5% Tungsten – UNS R05252

ElementMin %Max %
Tantalum (Ta)Balance
Tungsten (W)2.03.5
Carbon (C)0.015
Oxygen (O)0.020
Nitrogen (N)0.010
Hydrogen (H)0.0015
Niobium (Nb)0.50
Iron (Fe)0.010
Molybdenum (Mo)0.020
Silicon (Si)0.005

Metallurgical note: Tantalum is a refractory metal with a body-centered cubic (BCC) crystal structure. It exhibits exceptional corrosion resistance due to the formation of a stable, adherent oxide layer (Ta₂O₅) that protects the base metal from chemical attack. This oxide layer is self-healing in oxidizing environments and provides immunity to virtually all acids and chemicals except hydrofluoric acid, hot concentrated alkalis, and fuming sulfuric acid (oleum). Tantalum's high melting point (2996°C) makes it suitable for high-temperature applications in vacuum or inert atmospheres, though it may embrittle when exposed to oxygen above 300°C. The addition of 2.5% tungsten provides solid solution strengthening, increasing tensile and yield strength while maintaining excellent corrosion resistance. Tantalum is fully biocompatible, non-toxic, and radio-opaque, making it ideal for medical implant applications.

Complete Mechanical & Physical Properties – Tantalum (MPa / ksi)

Tantalum button head cap screws are supplied in annealed condition per applicable ASTM specifications. Strain-hardened (cold worked) conditions available upon request. Data represent typical values based on industry standards.

Mechanical Properties – Tantalum (Annealed Condition)

GradeTensile Strength (MPa)Tensile Strength (ksi)0.2% Yield Strength (MPa)0.2% Yield Strength (ksi)Elongation (%)Hardness
UNS R05200 (Commercially Pure)275 min40 min170 min25 min25 min80-150 HV
UNS R05200 (Typical)345-51750-75207-34530-5025-4080-150 HV
UNS R05252 (Ta-2.5W)380 min55 min240 min35 min20 min115-160 HV
UNS R05252 (Typical)448-58665-85310-44845-6520-30115-160 HV
Cold Worked (R05200)517-68975-100448-62065-902-10160-200 HV

Physical Properties – Tantalum

PropertyMetricImperial
Density16.6 g/cm³0.602 lb/in³
Melting Point2996 °C5425 °F
Boiling Point6100 °C11012 °F
Thermal Expansion (20-100°C)6.5 x 10⁻⁶ /°C3.6 x 10⁻⁶ /°F
Thermal Conductivity (20°C)57.5 W/m·K33.2 BTU·ft/(hr·ft²·°F)
Electrical Resistivity (20°C)13.5 μΩ·cm13.5 μΩ·cm
Electrical Conductivity13% IACS13% IACS
Specific Heat (20°C)0.15 J/g·°C0.036 cal/g·°C
Elastic Modulus (Tension)186 GPa27 x 10³ ksi
Poisson's Ratio0.340.34

High-Temperature Mechanical Properties – Tantalum

Temperature (°C)Tensile Strength (MPa)0.2% Yield Strength (MPa)Elongation (%)
2034520735
20031017230
40027613828
60024111025
8002079023
10001726920
12001385518

Note: High-temperature testing in vacuum or inert atmosphere. Tantalum may embrittle in oxygen above 300°C.

High‑Temperature Performance of Tantalum Button Head Screws

Tantalum is a refractory metal with exceptional high-temperature strength and stability in vacuum or inert atmospheres. The material maintains useful mechanical properties up to 2000°C (3632°F) in non-oxidizing environments, making it suitable for extreme temperature applications in vacuum furnaces, rocket engines, and aerospace propulsion systems. Tantalum's melting point of 2996°C (5425°F) is among the highest of all metals, exceeded only by tungsten and rhenium. The recrystallization temperature of tantalum is approximately 1200-1400°C, depending on purity and prior cold work. In oxidizing atmospheres, tantalum forms a protective oxide layer (Ta₂O₅) at moderate temperatures but may embrittle above 300°C due to oxygen diffusion. Therefore, tantalum fasteners are typically specified for high-temperature applications in vacuum, inert gas, or reducing atmospheres. Ta-2.5W alloy offers improved high-temperature strength compared to pure tantalum while maintaining similar oxidation behavior.

Elevated Temperature Capabilities

PropertyValue
Maximum Service Temperature (Vacuum/Inert Gas)2000°C (3632°F)
Maximum Service Temperature (Oxidizing)300°C (570°F) – limited by embrittlement
Recrystallization Temperature1200-1400°C (2192-2552°F)
Melting Point2996°C (5425°F)

Exceptional Corrosion Resistance of Tantalum Button Head Screws

Tantalum is renowned for its outstanding corrosion resistance, often described as similar to glass but with the mechanical properties of a metal. The material forms a stable, adherent, and self-healing oxide layer (Ta₂O₅) that provides protection against virtually all acids and chemicals except hydrofluoric acid, hot concentrated alkalis, and fuming sulfuric acid (oleum). Tantalum exhibits zero or near-zero corrosion rates in most aggressive media, making it the material of choice for critical chemical processing applications where other materials fail.

Corrosion Resistance to Common Media

MediumTemperature LimitCorrosion Rate
Hydrochloric Acid (all concentrations)Up to boilingNil
Nitric Acid (all concentrations)Up to boilingNil
Sulfuric AcidUp to 175°C (350°F)Nil
Phosphoric AcidUp to 150°C (300°F)Nil
Acetic AcidUp to boilingNil
Aqua RegiaUp to boilingNil
Chlorine (wet or dry)Up to 350°C (662°F)Nil
Hydrofluoric AcidAny temperatureSevere attack – not recommended
Hot Concentrated Alkalis (NaOH, KOH)Above 50°CModerate attack
Fuming Sulfuric Acid (Oleum)AmbientLimited resistance

The following list represents media to which tantalum exhibits nil or negligible corrosion (rates <0.05 mm/year) at temperatures up to at least 150°C (302°F):

  • Acetic acid
  • Acetic anhydride
  • Acetone
  • Alcohols
  • Aluminum chloride
  • Aluminum sulfate
  • Ammonium chloride
  • Ammonium nitrate
  • Ammonium phosphate
  • Ammonium sulfate
  • Aqua regia
  • Barium chloride
  • Benzoic acid
  • Body fluids
  • Boric acid
  • Bromine (dry, <300°C)
  • Butyric acid
  • Calcium chloride
  • Calcium hydroxide
  • Carbolic acid
  • Carbon dioxide
  • Chloric acid
  • Chlorinated brine
  • Chlorine (dry, <250°C)
  • Chlorine (wet, <350°C)
  • Chloroacetic acid
  • Chromic acid
  • Citric acid
  • Copper salts
  • Fatty acids
  • Ferric chloride
  • Ferric sulfate
  • Food stuffs
  • Formaldehyde
  • Formic acid
  • Glycerine
  • Hydrobromic acid
  • Hydrocarbons
  • Hydrochloric acid
  • Hydrogen bromide (<400°C)
  • Hydrogen chloride (<350°C)
  • Hydrogen peroxide
  • Hydrogen sulfide
  • Lactic acid
  • Magnesium chloride
  • Magnesium sulfate
  • Maleic acid
  • Mercuric chloride
  • Methyl alcohol
  • Milk
  • Mineral oils
  • Mixed acids (sulfuric-nitric)
  • Nickel salts
  • Nitric acid
  • Nitric acid (fuming)
  • Nitric oxides
  • Nitrogen (<300°C)
  • Nitrous acid
  • Organic acids
  • Oxalic acid
  • Oxygen (<300°C)
  • Petroleum products
  • Phenol
  • Phosphoric acid (<4ppm F, <180°C)
  • Pickling acids (except HNO3-HF)
  • Potassium bromide
  • Potassium chloride
  • Potassium dichromate
  • Potassium nitrate
  • Potassium permanganate
  • Potassium sulfate
  • Propionic acid
  • Refrigerants
  • Sea water
  • Silver nitrate
  • Sodium acetate
  • Sodium bisulfate (solution)
  • Sodium bromide
  • Sodium chlorate
  • Sodium chloride
  • Sodium cyanide
  • Sodium dichromate
  • Sodium hypochlorite
  • Sodium nitrate
  • Sodium nitrite
  • Sodium phosphate
  • Sodium silicate
  • Sodium sulfate
  • Sodium sulfide
  • Sodium sulfite
  • Sodium thiosulfate
  • Stearic acid
  • Succinic acid
  • Sugar
  • Sulfamic acid
  • Sulfur (<500°C)
  • Sulfur dioxide
  • Sulfuric acid (<175°C)
  • Sulfurous acid
  • Tannic acid
  • Tartaric acid
  • Zinc chloride
  • Zinc sulfate

Media to Avoid with Tantalum Fasteners

  • Hydrofluoric acid (HF) – any concentration, any temperature
  • Hot concentrated alkalis – sodium hydroxide (NaOH), potassium hydroxide (KOH) above 50°C
  • Fuming sulfuric acid (oleum) – limited resistance
  • Ammonium hydroxide – limited resistance
  • Fluoride salts – may cause attack
  • Hydrogen >300°C – may cause embrittlement
  • Oxygen >300°C – may cause embrittlement

Manufacturing Standards – Tantalum Button Head Cap Screws

All tantalum button head cap screws are manufactured and tested to meet the following standards:

ASTM B708ASTM B521ASTM F560AMS 7849ASME B18.3ISO 7380DIN 912EN 10204 3.1/3.2

We offer surface finishes: plain (as-machined), chemically cleaned, passivated, or electropolished for medical applications. Controlled annealing processes per ASTM specifications ensure consistent mechanical properties. Specialized CNC machining, thread rolling, and precision broaching for accurate button head geometry with hex socket drive. Class 2A/3A/6g thread fit. 100% inspection available including dimensional inspection, thread verification, 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.

Why RAYCHIN LIMITED – The Tantalum Fastener Authority

Specialized refractory metal expertise: Decades of experience with tantalum, niobium, and other refractory metals. We ensure precise processing to maintain material purity and corrosion resistance. In‑house PMI verifies chemistry of every heat. Our tantalum button head cap screws achieve full traceability and certified properties. Metallurgical engineering support for corrosion and high-temperature applications.
Global certifications: ISO 9001, AS9100D, ISO 13485 (medical), PED, API Q1, NADCAP accredited processes. All screws supplied with EN 10204 3.1/3.2 certifications, material test reports, and mill certifications. Complete in-house manufacturing control from raw material to finished product.
Precision manufacturing: CNC turning, thread rolling, and hex broaching ensure accurate button head geometry with precision socket drive. Class 2A/3A/6g thread fit. 100% inspection available. Special tooling for tantalum's unique machining characteristics – tantalum is relatively soft but can gall and requires sharp tools and proper lubrication. Cleanroom manufacturing available for medical and semiconductor applications.
Custom solutions: Special head configurations, non-standard lengths, proprietary drives, and tailored packaging. In-house metallurgical laboratory and failure analysis capabilities. Application-specific design consultation for corrosion and high-temperature applications. Flexible capacity for prototype and production volumes. Cleanroom wash and packaging available for medical and semiconductor applications.

Contact the tantalum fastener experts

Request a quotation for tantalum button head cap screws, tantalum button head screws, tantalum socket screws – any standard (ASME, ISO, DIN) – any condition (annealed, stress-relieved), any quantity. Global delivery. Mechanical and corrosion data in MPa/ksi available for all products. Medical-grade tantalum per ASTM F560 available.

sales@ray-chin.com | +86 534 2166 566

Our team provides technical support in English, German, Mandarin, Japanese. Request a quote, sample requests, and material evaluation available.


RAYCHIN LIMITED – World‑class manufacturer of tantalum button head cap screws: precision button head screws, low-profile socket screws – inch/metric series. Grades: Commercially Pure Tantalum (UNS R05200, UNS R05400), Tantalum 2.5% Tungsten (UNS R05252). Compliant with ASTM B708, ASTM B521, ASTM F560, AMS 7849, ASME B18.3, ISO 7380, DIN 912. Chemical processing, medical, pharmaceutical, semiconductor, aerospace, vacuum furnace industries. Full traceability, ASTM certifications, NADCAP quality, PED, ISO 13485. Refractory metal fasteners with exceptional corrosion resistance (immune to most acids) and high-temperature capability in vacuum/inert atmospheres. Biocompatible and radio-opaque for medical implant applications. All mechanical properties certified in MPa and ksi. Cleanroom packaging available for sensitive applications.

Head office: Taoyuan Road, East District, Pingyuan Economic Development Zone, Shandong, China

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