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Molybdenum Bolts

Molybdenum bolts possesses a very high melting point of 2620°C, a low coefficient of thermal expansion and a high level of thermal conductivity. Because molybdenum Bolts have the ability to withstand extremely high temperatures without changing shape, expanding or softening significantly, they are ideal for high strength / high temperature applications that are shielded from oxygen. Exposing molybdenum bolts to oxygen above 600°C will cause them to readily oxidize.

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

Molybdenum Bolts find their way into high temperature vacuum furnaces, glass production, military and space applications where oxygen is not present.

Extreme high temperature stability & strength
Maintains strength at elevated temperatures
Low distortion at high temperature
Molybdenum must be used in vacuum or inert gas at high temperatures

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RAYCHIN LIMITED

Name: Molybdenum Bolts
SKU: 0

Molybdenum Bolts · Hex Head Cap Screws · Heavy Hex Bolts · Inch & Metric · Pure Mo / TZM / MoLa

Molybdenum Bolts: Ultra-High Purity Refractory Metal Bolts for Extreme Temperature Environments

Pure Mo (≥99.95%) | TZM (Mo-Ti-Zr-C) | MoLa (Mo-La₂O₃) | ASTM B386 / B387

RAYCHIN LIMITED is a leading manufacturer of Molybdenum Bolts – precision-engineered fasteners produced from refractory molybdenum and its alloys, delivering exceptional high-temperature strength, thermal stability, and resistance to creep in extreme environments. With a melting point exceeding 2600°C (4700°F), molybdenum bolts retain structural integrity under vacuum, reducing atmospheres, and severe thermal cycling. Our comprehensive product line includes molybdenum hex bolts, hex head cap screws, heavy hex bolts, flange bolts, and structural bolts – all manufactured to the highest precision standards. Available grades include Pure Molybdenum (≥99.95%), TZM alloy (Mo-0.5Ti-0.08Zr-0.02C), and Molybdenum Lanthanum (MoLa) with enhanced recrystallization temperature. Our portfolio includes all standard and custom configurations manufactured to NAS, AN, MS, ANSI, ASTM, ASME, SAE, API, NACE, ISO, DIN and KS standards, including ASTM B386/B387, ISO 4017/4014, DIN 931, DIN 933, and ASME B18.2.1. Whether you require molybdenum bolts for high-temperature vacuum furnaces, semiconductor sputtering equipment, sapphire crystal growth systems, or aerospace propulsion components, RAYCHIN delivers precision, quality, and full traceability. All mechanical properties are presented in MPa and ksi (kilopound per square inch).

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Molybdenum Bolts – Design & Configurations

Hex Head Cap Screws (Finished Hex)

Molybdenum hex head cap screws are precision fasteners featuring a flat washer facing under the bolt head, providing a larger bearing surface area and superior clamping pressure for critical high-temperature applications. Manufactured to tight dimensional tolerances per ASME B18.2.1 (inch series), ISO 4014 / DIN 931 (metric, partially threaded), and ISO 4017 / DIN 933 (fully threaded). Available in diameters from M2 to M36 (#0 to 1-1/2").

Heavy Hex Bolts

Molybdenum heavy hex bolts feature a larger head width across flats compared to finished hex bolts, providing increased bearing area and load distribution for heavy-duty flange connections and furnace assemblies. Manufactured to ASME B18.2.1 (inch) and DIN 931 (metric) standards. Used extensively in high-temperature vacuum furnaces, heat shields, and semiconductor processing equipment where maximum clamping force and thermal stability are required.

Thread Specifications

Molybdenum bolts available with Unified Coarse (UNC), Unified Fine (UNF), UNJF-3A (aerospace), and metric coarse/fine threads. Thread classes 2A, 3A, 6g. Precision rolled threads for superior fatigue life. Full thread (threaded to head) or partial thread options available. Custom thread specifications available upon request. Available in stress-relieved or recrystallized conditions per application requirements.

Aerospace & Military Standards

Our molybdenum bolts meet applicable sections of NAS1802 (hex bolts), NASM 8830, MS16995, and AN42-AN73. Full compliance with ASTM B386 (plate/sheet/foil) and ASTM B387 (rod/bar/wire) for material and mechanical properties. Silver plating per AMS 2410 available for anti-galling. Cleanroom packaging available for semiconductor and aerospace applications.

Alloy Grades: TZM & MoLa

TZM alloy bolts (Mo-0.5Ti-0.08Zr-0.02C) offer higher recrystallization temperature (~1400°C), improved strength, and creep resistance compared to pure Mo. MoLa alloy bolts (Mo doped with La₂O₃) exhibit enhanced ductility and high-temperature stability. Both alloys available across all bolt types for applications exceeding 1400°C in vacuum or reducing atmospheres.

Custom & Non-Standard Bolts

Need special head configurations, proprietary drives (Torx, Robertson), non‑standard lengths, or unique thread forms? RAYCHIN engineers design and produce custom molybdenum bolts to your exact specifications – any grade (pure Mo, TZM, MoLa), any condition (stress relieved, recrystallized), with full material traceability. Prototype to production volumes supported. In-house metallurgical laboratory ensures optimal performance.

Critical Applications of Molybdenum Bolts

High-Temperature Vacuum Furnaces

Molybdenum bolts are essential in vacuum furnace construction, including hot zones, heating element supports, heat shields, and hearth assemblies. They maintain structural integrity at temperatures exceeding 1700°C (3090°F) in vacuum or inert gas environments where tungsten is too expensive and superalloys fail. Used in sintering furnaces, brazing furnaces, and annealing furnaces.

Semiconductor & Sputtering Equipment

Molybdenum bolts in semiconductor manufacturing equipment, including sputtering targets, PVD chambers, ion implanters, and wafer processing systems. Molybdenum's low coefficient of thermal expansion (5.1 x 10⁻⁶ /K), high thermal conductivity (138 W/m·K), and non-contaminating properties (no outgassing) make it ideal for ultra-high-vacuum (UHV) environments. Essential for securing electrodes, shields, and process kits.

Sapphire Crystal Growth & Glass Melting

Molybdenum bolts used in sapphire crystal growth furnaces (Kyropoulos, Czochralski) and glass melting electrodes. Molybdenum withstands molten glass corrosion and extreme temperatures required for LED sapphire substrate production. Fasteners secure crucible assemblies, heat shields, and electrode holders in aggressive molten environments.

Aerospace & Defense

Molybdenum bolts in rocket engine components, nozzle assemblies, re-entry vehicle heat shields, and supersonic aircraft skin elements. Molybdenum alloys maintain strength at extreme temperatures where other metals would soften or melt. Used in thrust vector control systems and high-temperature structural joints.

Nuclear Engineering

Molybdenum bolts in nuclear reactors, particle accelerators, and experimental fusion devices. Molybdenum exhibits excellent resistance to radiation damage and retains mechanical properties under neutron irradiation. Used for fuel cladding supports, control rod mechanisms, and plasma-facing component fasteners.

Research & Experimental Systems

Molybdenum bolts employed in experimental reactor systems, mechanical stress testing at elevated temperatures, and evaluation of refractory fastening solutions. Research applications include high-temperature mechanical testing and evaluation of refractory fastening technologies.

International Standards & Global Designations – Molybdenum Bolts

RAYCHIN LIMITED manufactures molybdenum bolts from vacuum arc melted (VAR) or powder metallurgy (PM) material conforming to the most widely used national and international specifications. All material is traceable to the mill.

Designation	Standard / Specification	Description
Pure Molybdenum	Mo ≥99.9% – ≥99.95%	Unalloyed molybdenum, highest purity available; excellent thermal conductivity, low vapor pressure
ASTM B386 / B386M	Standard Specification for Molybdenum and Molybdenum Alloy Plate, Sheet, Strip, and Foil	Covers grades 360 (vacuum arc melted pure Mo), 361 (powder metallurgy pure Mo), 363 (TZM), 364 (powder metallurgy TZM), 365 (low C Mo), 366 (Mo-30W)
ASTM B387 / B387M	Standard Specification for Molybdenum and Molybdenum Alloy Bar, Rod, and Wire	Primary material specification for molybdenum fastener stock; covers same grades as B386
TZM Alloy	Mo-0.5Ti-0.08Zr-0.02C	Molybdenum alloy with titanium, zirconium, carbon for enhanced strength and recrystallization temperature
MoLa (Mo-La₂O₃)	Mo with 0.3-0.6% Lanthanum Oxide	Dispersion-strengthened molybdenum with improved ductility and high-temperature stability
ISO 4017:2011 / DIN 933	Hex head cap screws – metric series	Dimensional standard for fully threaded hex bolts; Molybdenum bolts per this specification
ISO 4014 / DIN 931	Hex head bolts – metric series	Dimensional standard for partially threaded hex bolts
ASME B18.2.1	Square and hex bolts (inch series)	Dimensional standards for inch-series bolts and hex cap screws
JIS B 1180	Hex head bolts – metric series	Japanese Industrial Standard for hex bolts
ISO 4762 / DIN 912	Socket head cap screws – metric	Applicable for molybdenum socket head bolts

ASTM B386 ASTM B387 Pure Mo 99.95% TZM MoLa ISO 4017 ISO 4014 DIN 931 DIN 933 ASME B18.2.1 JIS B 1180

Chemical Composition (Weight %) – Molybdenum Alloys for Bolts

Our molybdenum bolts are produced from vacuum arc melted (VAR) or powder metallurgy (PM) material conforming to ASTM B386/B387 and industry standards.

Pure Molybdenum (Grade 360 / 361) – Mo ≥99.95%

Element	Min %	Max %	Typical
Molybdenum (Mo)	99.9	Balance	99.95
Iron (Fe)	—	0.010	0.004
Nickel (Ni)	—	0.005	0.002
Silicon (Si)	—	0.010	0.0013
Carbon (C)	—	0.030	0.0028
Oxygen (O)	—	0.0070	0.005
Nitrogen (N)	—	0.002	0.002
Aluminum (Al)	—	0.002	0.0005
Calcium (Ca)	—	0.002	<0.001
Magnesium (Mg)	—	0.002	<0.0005

TZM Alloy (Grade 363 / 364) – Mo-0.5Ti-0.08Zr-0.02C

Element	Min %	Max %	Typical
Molybdenum (Mo)	Balance	Balance	~99.0
Titanium (Ti)	0.40	0.55	0.50
Zirconium (Zr)	0.06	0.12	0.08
Carbon (C)	0.01	0.04	0.02
Iron (Fe)	—	0.010	0.005
Nickel (Ni)	—	0.005	0.002
Silicon (Si)	—	0.010	0.005
Oxygen (O)	—	0.0030	0.002
Nitrogen (N)	—	0.002	0.001

MoLa Alloy (Mo with Lanthanum Oxide)

Element	Min %	Max %	Typical
Molybdenum (Mo)	Balance	Balance	~99.5
Lanthanum Oxide (La₂O₃)	0.3	0.6	0.4
Other impurities	—	0.10	<0.05

Metallurgical note: Molybdenum is a refractory metal with a body-centered cubic (BCC) crystal structure. Pure molybdenum bolts are typically supplied in stress-relieved condition (recrystallization temperature ~1100°C). TZM alloy offers significantly higher recrystallization temperature (~1400°C) and improved creep strength through carbide dispersion strengthening. MoLa (lanthanated molybdenum) maintains ductility after high-temperature exposure due to oxide dispersion pinning grain boundaries. All molybdenum bolts should be handled with care due to limited ductility at room temperature, becoming more ductile above ductile-to-brittle transition temperature (DBTT).

Complete Mechanical & Physical Properties – Molybdenum Bolts (MPa / ksi)

Molybdenum bolts are supplied in various conditions (stress relieved, recrystallized) per ASTM B387. Data represent typical values based on industry standards.

Mechanical Properties – Pure Molybdenum Bolts

Condition	Tensile Strength (MPa)	Tensile Strength (ksi)	Yield Strength 0.2% (MPa)	Yield Strength 0.2% (ksi)	Elongation (%)	Hardness (Vickers)
Hard (Stress Relieved)	620-690	90-100	550-620	80-90	10-20	250
Soft (Recrystallized/Annealed)	485-550	70-80	415-450	60-65	20-30	200
Typical (Pure Mo)	515-1000	75-145	380-550	55-80	15-20	200-250

Mechanical Properties – TZM Alloy Bolts

Condition	Tensile Strength (MPa)	Tensile Strength (ksi)	Yield Strength 0.2% (MPa)	Yield Strength 0.2% (ksi)	Elongation (%)	Hardness
Stress Relieved	860-1035	125-150	690-860	100-125	8-15	300 HV
Recrystallized	620-760	90-110	550-620	80-90	15-25	230 HV

Physical Properties – Molybdenum

Property	Metric	Imperial	Notes
Density	10.22 g/cm³	0.369 lb/in³	Pure Mo
Density (TZM)	10.16 g/cm³	0.367 lb/in³	Slightly lower due to alloying
Melting Point	2617°C	4743°F	Pure Mo
Boiling Point	4612°C	8334°F
Elastic Modulus (E)	324-329 GPa	47.0-47.7 x 10³ ksi	Stress relieved condition
Poisson's Ratio	0.293-0.31	0.293-0.31
Thermal Expansion (20-100°C)	5.1 x 10⁻⁶ /K	2.8 x 10⁻⁶ /°F	Very low CTE
Thermal Conductivity	138 W/m·K	960 BTU·in/(hr·ft²·°F)	Excellent conductivity
Electrical Resistivity	5.7 µΩ·cm	2.24 µΩ·in	At 20°C
Specific Heat	251 J/kg·K	0.06 BTU/lb·°F	At 25°C

High‑Temperature Performance of Molybdenum Bolts

Molybdenum and its alloys are renowned for exceptional high-temperature strength and stability. Pure molybdenum maintains useful mechanical properties up to 1700°C (3090°F) in vacuum or reducing atmospheres, with TZM extending capability further through carbide strengthening. However, molybdenum oxidizes rapidly above 600°C in air, limiting use to vacuum, inert gas, or reducing environments unless protected by coatings.

Elevated Temperature Capabilities

Property	Pure Molybdenum	TZM Alloy	MoLa Alloy
Max Service Temp (vacuum/inert)	1700°C (3090°F)	1400-1500°C (2550-2730°F)	1700°C (3090°F)
Recrystallization Temp	1100°C (2010°F)	1400°C (2550°F)	1300-1500°C
Creep Resistance	Good	Excellent	Very Good
Tensile Strength @ 1000°C	~300 MPa (43 ksi)	~450 MPa (65 ksi)	~350 MPa (51 ksi)
Oxidation Onset in Air	600°C (1110°F) – formation of volatile MoO₃

High-Temperature Comparison – Refractory Metals

Alloy	Max Service Temp (Vacuum)	Density (g/cm³)	Typical Application
Molybdenum (Pure)	1700°C	10.22	Furnace hot zones, electrodes
TZM Alloy	1500°C	10.16	High-strength furnace components, rocket nozzles
MoLa (La₂O₃)	1700°C	10.20	Heating elements, wire applications
Tungsten (W)	2500°C	19.3	Highest temperature, but 2x density
Stainless Steel 316	~900°C	8.0	Lower temperature limit

Note: All molybdenum bolts must be used in vacuum, inert gas, or reducing atmosphere (H₂) above 600°C to prevent catastrophic oxidation. For air applications, protective coatings (MoSi₂, Al₂O₃, Y₂O₃) may be applied.

Corrosion Resistance of Molybdenum Bolts

Molybdenum exhibits excellent resistance to many corrosive media, particularly in reducing environments and in the absence of oxidizing agents. However, rapid oxidation occurs in air above 600°C.

Acid Resistance: Excellent resistance to hydrochloric acid (HCl), sulfuric acid (H₂SO₄) at moderate temperatures, and phosphoric acid (H₃PO₄). Resists most non-oxidizing mineral acids. Rapid attack in nitric acid (HNO₃) and other oxidizing acids.
Alkalis: Generally good resistance, but can be attacked by fused alkalis. Resistant to many molten salts.
Liquid Metals: Excellent resistance to liquid lithium, sodium, potassium, and bismuth, making it valuable in nuclear coolant systems.
Halogens: Resistant to fluorine, chlorine, and bromine at moderate temperatures; attacks at higher temperatures.
Oxidation: Forms volatile MoO₃ above 600°C in air; requires protective atmosphere or coating for high-temperature air service.
Hydrogen: Excellent resistance to hydrogen attack even at high temperatures (unlike steel).
Sulfur Compounds: Good resistance to sulfur, hydrogen sulfide, and sulfur dioxide.
Glass Corrosion: Outstanding resistance to molten glass, widely used in glass melting electrodes and stirrers.
Bimetallic Corrosion: Can be safely connected to tungsten, tantalum, and graphite. Avoid direct contact with aluminum, zinc, and copper at high temperatures due to eutectic formation.

Manufacturing Standards – Molybdenum Bolts

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

ASTM B386ASTM B387ISO 4017ISO 4014DIN 931DIN 933ASME B18.2.1JIS B 1180ISO 4762DIN 912NAS1802MS16995EN 10204 3.1/3.2

We offer surface finishes: black (as-machined), chemical cleaned, ground, polished, and passivated. Special coatings (MoSi₂, Al₂O₃, Y₂O₃) available for oxidation protection. Full traceability and destructive/non‑destructive testing available (UT, PMI, MPI). ISO 13485 certified for medical applications with cleanroom packaging available.

Why RAYCHIN LIMITED – The Molybdenum Bolt Authority

Refractory metal expertise: Decades of experience with molybdenum, TZM, and MoLa alloys. We ensure precise processing: stress relieving, recrystallization annealing, and surface finishing per ASTM B386/B387 standards. In‑house PMI verifies chemistry of every heat. Our molybdenum bolts achieve full traceability and certified properties.

Global certifications: ISO 9001, AS9100D, ISO 13485 (medical), PED, API Q1, NADCAP accredited processes. All bolts supplied with EN 10204 3.1/3.2 certifications, material test reports, and NACE compliance when required.

Precision machining & thread rolling: CNC turning and precision thread rolling ensure accurate head geometry and thread form per ASME, ISO, and DIN standards. Class 2A/3A/6g thread fit. 100% inspection available. Special tooling for molybdenum's unique machining characteristics (brittle behavior at room temperature).

Custom solutions: Special head configurations, proprietary drives, non‑standard lengths, custom alloys, and tailored packaging. In-house metallurgical laboratory and failure analysis capabilities. Prototype to production volumes supported. Cleanroom wash and packaging available for semiconductor and medical applications.

Contact the molybdenum bolt experts

Request a quotation for molybdenum hex bolts, hex head cap screws, heavy hex bolts, TZM bolts, MoLa bolts – any standard (ASME B18.2.1, ISO 4014/4017, DIN 931/933) – any grade (Pure Mo, TZM, MoLa) – any condition (stress relieved, recrystallized), any quantity. Global delivery. Mechanical data in MPa/ksi available for all products.

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