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Molybdenum Screws

Molybdenum screws possesses a very high melting point of 2620°C, a low coefficient of thermal expansion and a high level of thermal conductivity. Because molybdenum screws 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 screws to oxygen above 600°C will cause them to readily oxidize.

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Molybdenum screws 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 Screws
SKU: 0

Molybdenum Screws · Socket / Hex / Pan / Flat / Set · Inch & Metric · Pure Mo / TZM / MoLa

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

Pure Mo (≥99.95%) | TZM (Mo-Ti-Zr-C) | MoLa (Mo-La₂O₃) | ASTM B386 / B387 | ISO 4762 / DIN 912

RAYCHIN LIMITED is a leading manufacturer of Molybdenum Screws – precision threaded 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) and the ability to withstand temperatures up to 1700°C in vacuum or reducing atmospheres, molybdenum screws retain structural integrity where conventional fasteners fail. Our comprehensive product line includes molybdenum socket head cap screws, hex head screws, pan head screws, flat head screws, button head screws, and set screws – 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 4762, DIN 912, ISO 4017, ISO 4032, and ASME B18.3. Whether you require molybdenum screws 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 Screws – Design & Configurations

Socket Head Cap Screws

Molybdenum socket head cap screws feature a cylindrical head with internal hex drive, providing high tightening torque and clean appearance in confined spaces. Manufactured to ASME B18.3 (inch) and ISO 4762 / DIN 912 (metric). Available with standard or reduced head heights. Ideal for high-temperature furnace assemblies, heat shields, and secure connections in ultra-high-vacuum (UHV) environments. Available with ventilation holes for vacuum outgassing in semiconductor equipment.

Hex Head Screws

Molybdenum hex head screws are designed for heavy-duty bolting applications requiring high clamping forces. Manufactured to ASME B18.2.1 (inch) and ISO 4014 / ISO 4017 (metric). Full range of diameters from M1.6 to M48 (#0 to 2"). Precision forged heads and rolled threads for maximum strength. Used extensively in crystal growth furnaces, glass melting electrodes, and high-temperature structural joints.

Pan Head / Machine Screws

Molybdenum pan head screws feature a domed top and flat bearing surface, offering a balanced profile for visibility and strength. Drives include Phillips (crosshead), slotted, and internal hex. Manufactured to ASME B18.6.3 (inch) and ISO 1580 / ISO 7045 (metric). Ideal for semiconductor processing equipment, control panels, and furnace instrumentation where a low profile with good driving torque is needed.

Flat Head Countersunk Screws

Molybdenum flat head screws (countersunk) feature a conical bearing surface and flat top for flush installation. Available with 82° (inch), 100° (aerospace), and 90° (metric) countersink angles. Ideal for sputtering targets, heat shields, and applications requiring a smooth, snag-free finish in vacuum systems. Manufactured to ASME B18.3 (inch) and ISO 10642 (metric).

Button Head Cap Screws

Molybdenum button head screws combine a low-profile rounded head with internal hex drive, providing a wide bearing surface for clamping thin materials. Head dimensions conform to ASME B18.3 (inch) and ISO 7380 (metric). Low head profile prevents interference with moving parts in furnace assemblies and reduces snag points in vacuum chambers. Excellent for FPD production devices and semiconductor equipment where cleanroom compatibility is required.

Set Screws (Grub Screws)

Molybdenum set screws are headless fasteners with various point styles: cup point, cone point, flat point, and dog point. Used to secure rotating components such as electrodes, heating elements, and collars onto shafts in high-temperature furnaces. Available with hex socket or slotted drive. Manufactured to ASME B18.3 (inch) and ISO 4026-4029 (metric). Exceptional resistance to loosening under thermal cycling in corrosive environments.

Thread Specifications

Molybdenum screws 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 or partial thread options available. Custom thread specifications available upon request. Available in stress-relieved or recrystallized conditions per application requirements.

Alloy Grades: TZM & MoLa

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

Custom & Non-Standard Screws

Need special head configurations, proprietary drives (Torx, Robertson), non‑standard lengths, or unique thread forms? RAYCHIN engineers design and produce custom molybdenum screws to your exact specifications – any grade (pure Mo, TZM, MoLa), any condition (stress relieved, recrystallized), with full material traceability. Prototype to production volumes supported. Cleanroom wash and packaging available for semiconductor and medical applications.

Critical Applications of Molybdenum Screws

High-Temperature Vacuum Furnaces

Molybdenum screws 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 superalloys fail. Used in sintering furnaces, brazing furnaces, and annealing furnaces. Socket head screws secure heating elements and heat shields, while set screws fix electrodes and thermocouple fittings.

Semiconductor & Sputtering Equipment

Molybdenum screws 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. Ventilated screws available for vacuum outgassing.

Sapphire Crystal Growth & Glass Melting

Molybdenum screws 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. Screws secure crucible assemblies, heat shields, and electrode holders in aggressive molten environments. Flat head screws provide flush mounting in confined spaces.

Aerospace & Defense

Molybdenum screws 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. Locking set screws prevent loosening under extreme vibration during launch and re-entry.

Nuclear Engineering

Molybdenum screws 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. Pan head screws provide secure mounting for instrumentation in high-radiation zones.

Medical & X-ray Equipment

Molybdenum screws in X-ray tube assemblies, radiation shielding components, and medical isotope production equipment. Molybdenum's high atomic number and thermal properties make it suitable for X-ray targets and collimators. Screws secure targets and cathodes under high-voltage, high-temperature operation. Cleanroom packaging available for medical device applications requiring strict contamination control.

International Standards & Global Designations – Molybdenum Screws

RAYCHIN LIMITED manufactures molybdenum screws 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, Foil, and Ribbon	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 4762:2004	Hexagon socket head cap screws – metric series	Dimensional standard for molybdenum socket head screws, M1.6 to M64
DIN 912	Socket head cap screws – metric series	German standard, interchangeable with ISO 4762
ISO 4017 / DIN 933	Hex head cap screws – metric series (fully threaded)	Dimensional standard for molybdenum hex head screws
ASME B18.3	Socket head cap screws (inch series)	Dimensional standards for inch-series socket head screws
ASME B18.2.1	Hex head screws (inch series)	Dimensional standards for inch-series hex head screws
ISO 10642	Hexagon socket countersunk head screws (metric)	Dimensional standard for molybdenum flat head screws
ISO 7380	Button head screws – metric series	Dimensional standard for molybdenum button head screws

ASTM B386 ASTM B387 Pure Mo 99.95% TZM MoLa ISO 4762 DIN 912 ISO 4017 ASME B18.3 ASME B18.2.1

Chemical Composition (Weight %) – Molybdenum Alloys for Screws

Our molybdenum screws 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 screws are typically supplied in stress-relieved condition (recrystallization temperature ~1100°C) or soft/annealed condition. 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 screws 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 Screws (MPa / ksi)

Molybdenum screws are supplied in various conditions (hard/stress relieved, soft/annealed) per ASTM B387. Data represent typical values based on industry standards.

Mechanical Properties – Pure Molybdenum Screws

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	75	380	55	15	200-250

Mechanical Properties – TZM Alloy Screws

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	Pure Molybdenum	TZM Alloy	Comparison (SUS304)
Density (g/cm³)	10.22-10.3	10.16-10.20	7.93
Melting Point (°C)	2617-2625	2500-2600	1400-1450
Elastic Modulus (GPa)	324-330	320	193
Poisson's Ratio	0.293-0.31	0.31	0.29
Thermal Expansion (20-100°C) (x10⁻⁶/K)	5.1-5.35	5.3	17.3
Thermal Conductivity (W/m·K)	138-142	126	17
Electrical Resistivity (µΩ·cm)	5.7	5.3-5.5	72
Specific Heat (J/kg·K)	251	305	500

High‑Temperature Performance of Molybdenum Screws

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, forming volatile MoO₃, 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 – Molybdenum vs. Stainless Steel

Property	Molybdenum (Pure)	SUS304 Stainless Steel	Notes
Tensile Strength (MPa)	515-690	≥520	Comparable at RT
Yield Strength 0.2% (MPa)	380-620	≥205	Mo much stronger
Elongation (%)	10-20	≥40	SS more ductile
Specific Gravity	10.2	7.93	Mo denser
Elastic Modulus (GPa)	327	193	Mo 70% stiffer
Thermal Conductivity (W/m·K)	142	17	Mo 8x higher
Thermal Expansion (x10⁻⁶/K)	5.1	17.3	Mo much lower
Max Service Temp (air)	600°C (oxidizes)	~900°C	SS higher in air
Max Service Temp (vacuum)	1700°C	~900°C	Mo superior in vacuum

Note: All molybdenum screws 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 Screws

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. Its stability in various chemical environments makes it suitable for chemical processing equipment and research applications.

Acid Resistance: Excellent resistance to hydrochloric acid (HCl), sulfuric acid (H₂SO₄) up to 60% concentration at moderate temperatures, and phosphoric acid (H₃PO₄). Resists most non-oxidizing mineral acids. Rapid attack in nitric acid (HNO₃) and other oxidizing acids.
Alkalis: Stable in alkaline solutions (sodium hydroxide, ammonia), resisting corrosion effectively.
Liquid Metals: Excellent resistance to liquid lithium, sodium, potassium, and bismuth, making it valuable in nuclear coolant systems. Resists molten aluminum and zinc.
Halogens: Resistant to fluorine, chlorine, and bromine at moderate temperatures; forms halides at high 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.
Halide Salts: Resistant to corrosion and pitting attack by chlorides.
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.
Neutron Irradiation: Excellent resistance to radiation damage, retaining mechanical properties under neutron flux.

Manufacturing Standards – Molybdenum Screws

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

ASTM B386ASTM B387ISO 4762DIN 912ISO 4017ASME B18.3ASME B18.2.1ISO 10642ISO 7380ISO 1580DIN 85NAS1351MS16995EN 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. Batch cleanroom packaging available for orders containing multiple items of the same size.

Why RAYCHIN LIMITED – The Molybdenum Screw 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 screws achieve full traceability and certified properties.

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 NACE compliance when required.

Precision heading & thread rolling: CNC cold heading 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). Ventilated screw options available for vacuum applications.

Custom solutions: Special head configurations, proprietary drives (Torx, Robertson), non‑standard lengths, ventilated designs, 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 screw experts

Request a quotation for molybdenum socket head cap screws, hex head screws, pan head screws, set screws – any standard (ASME, ISO, DIN, NAS) – 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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