Welcome to RAYCHIN LIMITED

+86-531-59532816



Molybdenum Fasteners



Location： HOME - Special Fasteners - Molybdenum Fasteners - Molybdenum Shoulder Bolts

Molybdenum Shoulder Bolts

Molybdenum shoulder 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 shoulder 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 shoulder 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 shoulder 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

Request a Quote from RAYCHIN

We're here to help!

Request a Quote

RAYCHIN LIMITED

Name: Molybdenum Shoulder Bolts
SKU: 0

Molybdenum Shoulder Bolts · Precision Ground Shoulder · Hex Drive · Inch & Metric · Pure Mo / TZM / MoLa

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

Pure Mo (≥99.95%) | TZM (Mo-Ti-Zr-C) | MoLa (Mo-La₂O₃) | ASTM B386 / B387 | UNS R03630

RAYCHIN LIMITED is a leading manufacturer of Molybdenum Shoulder Bolts – precision fasteners produced from refractory molybdenum and its alloys, delivering exceptional high-temperature strength, thermal stability, and corrosion resistance in extreme environments. With a melting point of 2620°C (4760°F) and the ability to withstand temperatures up to 1700°C in vacuum or reducing atmospheres, molybdenum shoulder bolts retain structural integrity where conventional materials fail. Shoulder bolts (also called stripper bolts) are unique fasteners with three main parts: head, shoulder, and thread. The head has the largest diameter and is where the torque is applied, typically with a socket driver. The shoulder is smooth and unthreaded, and has a set diameter and length – its role is to act as a shaft or dowel for rotating parts, axles for rolling parts, guides for sliding elements, and pivot points. Our comprehensive product line includes molybdenum shoulder bolts, molybdenum stripper bolts, and precision shoulder screws – all manufactured to the highest precision standards. Available grades include Pure Molybdenum (≥99.95%), TZM alloy (Mo-0.5Ti-0.08Zr-0.02C, UNS R03630), 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, ASTM B384/B385, and UNS R03630. Whether you require molybdenum shoulder 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).

molybdenum shoulder boltsmolybdenum shoulder screwsmolybdenum stripper boltspure molybdenum shoulder boltsTZM shoulder boltsMoLa shoulder boltsASTM B387 shoulder boltsrefractory metal shoulder boltshigh temperature shoulder boltsvacuum furnace shoulder boltssemiconductor shoulder screwsmolybdenum alloy shoulder boltsmolybdenum precision shoulder boltsmolybdenum shoulder screwUNS R03630 shoulder boltsASTM B384 shoulder bolts

Molybdenum Shoulder Bolts – Design & Configurations

Precision Ground Shoulder

Molybdenum shoulder bolts feature a precision ground shoulder with tight diameter tolerances (typically h6 or h7). The shoulder acts as a bearing surface, shaft, or locating feature, eliminating the need for additional bushings. The shoulder is smooth and unthreaded, and has a set diameter and length – its role is to act as a shaft or dowel for rotating parts, axles for rolling parts, guides for sliding elements, and pivot points. Available in standard and custom shoulder lengths to meet exact application requirements. Shoulder diameters from M3 to M36 (#4 to 1-1/2").

Head Styles & Drive Types

Molybdenum shoulder bolts feature a head with the largest diameter where torque is applied, typically with a hex socket drive (Allen). Standard hex socket drive provides positive torque transmission and allows for flush or recessed installations. Also available with slotted drive, hex head, or custom drive configurations. Head styles include standard shoulder bolt head (reduced diameter) and heavy head options for increased bearing area. Vented versions available for UHV applications.

Thread Specifications

The threaded portion of a molybdenum shoulder bolt has a major diameter slightly smaller than the shoulder diameter. 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. Standard thread lengths or custom lengths available. Sizes from M3 to M36 (#4 to 1-1/2").

Alloy Grades: TZM & MoLa

TZM alloy shoulder bolts (Mo-0.5Ti-0.08Zr-0.02C, UNS R03630) offer higher recrystallization temperature (~1400°C), improved strength, and creep resistance compared to pure Mo. TZM is excellent for support structures in vacuum furnaces or other high temperature and oxygen free environments. MoLa alloy shoulder bolts (Mo doped with La₂O₃) exhibit enhanced ductility and high-temperature stability. Both alloys available for applications exceeding 1400°C.

Aerospace & Military Standards

Our molybdenum shoulder bolts meet applicable sections of NASM 5160 (shoulder screws), NAS1802, and MS16995 for geometry. 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 wash and cleanroom packaging available for semiconductor and aerospace applications – batch cleanroom packing provided for orders containing multiple items of the same size.

Custom & Non-Standard Shoulder Bolts

Need special shoulder diameters, non‑standard shoulder lengths, proprietary drives, or unique head configurations? RAYCHIN engineers design and produce custom molybdenum shoulder 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. Cleanroom wash and packaging available for sensitive applications.

Critical Applications of Molybdenum Shoulder Bolts

High-Temperature Vacuum Furnaces

Molybdenum shoulder bolts find their way into high temperature vacuum furnaces, glass production, military and space applications where oxygen is not present. They maintain structural integrity at temperatures exceeding 1700°C (3090°F) in vacuum or inert gas environments where superalloys fail. The precision ground shoulder acts as a locating dowel for heat shields and heating element supports, providing accurate alignment in furnace hot zones.

Semiconductor & Sputtering Equipment

Molybdenum shoulder bolts in semiconductor manufacturing equipment, including sputtering targets, PVD chambers, ion implanters, and wafer processing systems. Molybdenum's low coefficient of thermal expansion (5.5 × 10⁻⁶ /K), high thermal conductivity, and non-contaminating properties (no outgassing) make it ideal for ultra-high-vacuum (UHV) environments. The precision shoulder provides exact location of electrodes and shields.

Aerospace & Defense

Molybdenum shoulder 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 where the shoulder acts as a pivot point or locating dowel. Molybdenum has received increased interest in recent years for ballistic applications.

Nuclear Engineering

Molybdenum shoulder 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 where precise location is critical. Resists corrosion by liquid metal coolants (lithium, sodium, potassium).

Glass Melting & Sapphire Growth

Molybdenum shoulder 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. The precision ground shoulder provides accurate location of crucible assemblies and electrode holders in aggressive molten environments.

Medical & Industrial Equipment

Molybdenum shoulder bolts in medical imaging equipment, X-ray tube assemblies, and industrial machinery requiring heat resistance and precision alignment. Their ability to withstand extreme thermal cycling without deformation makes them ideal for precision manufacturing equipment operating at elevated temperatures. Used in applications where the shoulder acts as a guide for sliding elements or a shaft for rotating parts.

International Standards & Global Designations – Molybdenum Shoulder Bolts

RAYCHIN LIMITED manufactures molybdenum shoulder 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; melting point 2620°C
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-VAM), 364 (TZM-PM)
ASTM B387 / B387M	Standard Specification for Molybdenum and Molybdenum Alloy Bar, Rod, and Wire	Primary material specification for molybdenum shoulder bolt stock; covers same grades as ASTM B386
TZM Alloy	Mo-0.5Ti-0.08Zr-0.02C (UNS R03630)	Molybdenum alloy with titanium, zirconium, carbon for enhanced strength and recrystallization temperature (~1400°C)
UNS R03630	Unified Numbering System	Standard designation for TZM alloy
ASTM B384	Molybdenum and Molybdenum Alloy Forgings	Specification for molybdenum alloy forgings, relevant for TZM
ASTM B385	Molybdenum and Molybdenum Alloy Billets	Specification for molybdenum alloy billets
MoLa (Mo-La₂O₃)	Mo with 0.3-0.6% Lanthanum Oxide	Dispersion-strengthened molybdenum with improved ductility and high-temperature stability
ASME B18.3	Socket head cap screws (inch series)	Dimensional standards for inch-series socket head screws including shoulder bolts
ISO 7378	Shoulder screws – metric series	Dimensional standard for metric shoulder screws
NASM 5160	Shoulder screws – inch series	National Aerospace Standards for shoulder screws

ASTM B386 ASTM B387 ASTM B384 ASTM B385 UNS R03630 Pure Mo 99.95% TZM MoLa ASME B18.3 ISO 7378 NASM 5160

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

Our molybdenum shoulder 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 shoulder bolts are typically supplied in stress-relieved condition (recrystallization temperature ~1100-1200°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. The yield stress of molybdenum is sensitive to test temperature and strain rate. All molybdenum shoulder bolts must be used in vacuum, inert gas, or reducing atmospheres above 600°C to prevent catastrophic oxidation.

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

Molybdenum shoulder bolts 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

Property	Value (Metric)	Value (Imperial)	Notes
Tensile Strength (Stress Relieved)	620-690 MPa	90-100 ksi	At room temperature
Yield Strength (Stress Relieved)	550-620 MPa	80-90 ksi	0.2% offset
Tensile Strength (Annealed)	485-550 MPa	70-80 ksi	At room temperature
Yield Strength (Annealed)	415-450 MPa	60-65 ksi	0.2% offset
Elongation (Stress Relieved)	10-20%	10-20%
Elongation (Annealed)	20-30%	20-30%
Hardness (Stress Relieved)	250 HV	250 HV
Hardness (Annealed)	200 HV	200 HV

Mechanical Properties – TZM Alloy Shoulder 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 – Pure Molybdenum

Property	Metric	Imperial	Notes
Density	10.3 g/mL	0.372 lb/in³	At 25°C
Melting Point	2617-2620°C	4743-4760°F	Very high
Boiling Point	4612°C	8334°F
Elastic Modulus (20°C)	324-329 GPa	47.0-47.7 x 10³ ksi	Stress relieved condition
Elastic Modulus (870°C)	~276 GPa	40,000 ksi	1.3x carbon steel at RT
Thermal Expansion Coef. (20°C)	5.35 µm/m°C	2.97 µin/in°F	Very low CTE
Thermal Conductivity	138 W/m·K	958 BTU·in/(hr·ft²·°F)	Excellent conductivity
Electrical Resistivity (20°C)	5.0-5.7 µΩ·cm	1.97-2.24 µΩ·in
Creep Strength (980°C)	~17.5 kg/mm²	~172 MPa	Higher than conventional heat-resistance alloys
Recrystallization Temp	~1200°C	~2190°F

High‑Temperature Performance of Molybdenum Shoulder 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. Molybdenum has a very high melting point of 2620°C (4760°F), a low coefficient of thermal expansion (5.5× 10-6/°C) and a high level of thermal conductivity. Because molybdenum shoulder 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. The creep strength is about 17.5kg/mm² at 980°C and is higher than those of the conventional heat-resistance alloys. However, exposing molybdenum to oxygen above 600°C will cause them to readily oxidize.

Elevated Temperature Capabilities

Property	Pure Molybdenum	TZM Alloy	MoLa Alloy
Melting Point (°C)	2620-2625	~2600	2623
Max Service Temp (vacuum/inert)	1700°C (3090°F)	1400-1500°C (2550-2730°F)	1700°C (3090°F)
Recrystallization Temp	1100-1200°C	1400°C	1300-1500°C
Elastic Modulus @ 870°C	276 GPa	~280 GPa	276 GPa
Creep Strength @ 980°C	17.5 kg/mm² (172 MPa)	~25 kg/mm²	~20 kg/mm²
Oxidation Onset in Air	490-600°C (910-1110°F) – formation of volatile MoO₃

Molybdenum shoulder bolts support use with vacuum equipment in high-temperature environments. The oxidation of molybdenum proceeds, up to 490°C, according to the parabolic law, but above this temperature, the vaporization of MoO₃ occurs, and oxidation proceeds rapidly. When molybdenum is used as a heat-resistance material, it is necessary to use protective coatings such as Cr-Ni double layer deposit coating, siliconizing, or chromizing.

Corrosion Resistance of Molybdenum Shoulder 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 490-600°C.

Oxidation Resistance: Forms volatile MoO₃ above 490-600°C in air; requires protective atmosphere or coating for high-temperature air service. Cr and Ni double layer deposit coating can provide up to 700 hours oxidation resistance at 1000°C.
Chloride Solutions: Molybdenum-containing alloys have superior resistance against pitting attack in 0.1 M NaCl solutions up to 200°C. Above 200°C, pitting attack may degenerate into different kinds of localized or general attack at rather high potentials.
Liquid Metals: Excellent resistance to liquid lithium, sodium, potassium, and bismuth, making it valuable in nuclear coolant systems.
Hydrogen: Excellent resistance to hydrogen attack even at high temperatures.
Glass Corrosion: Outstanding resistance to molten glass, widely used in glass melting electrodes and stirrers.
Acid Resistance: Molybdenum is resistant to many non-oxidizing mineral acids. However, it has high solubility in concentrated sulphuric acid and nitric acid.

Manufacturing Standards – Molybdenum Shoulder Bolts

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

ASTM B386ASTM B387ASTM B384ASTM B385UNS R03630ASME B18.3ISO 7378NASM 5160NAS1802MS16995EN 10204 3.1/3.2

We offer surface finishes: black (as-machined), chemical cleaned, ground, polished, and passivated. Special coatings (Cr-Ni double layer, MoSi₂, Al₂O₃) available for oxidation protection. Cleanroom wash and cleanroom packaging available for semiconductor, medical, and aerospace applications – batch cleanroom packing provided for orders containing multiple items of the same size. Full traceability and destructive/non‑destructive testing available (UT, PMI, MPI). ISO 9001, AS9100D, ISO 13485 certified.

Why RAYCHIN LIMITED – The Molybdenum Shoulder 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 shoulder bolts achieve full traceability and certified properties with precision ground shoulders to tight tolerances.

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

Precision grinding & thread rolling: CNC centerless grinding ensures precise shoulder diameter tolerances (h6/h7). Precision thread rolling ensures accurate thread geometry per ASME, ISO, and DIN standards. Class 2A/3A/6g thread fit. 100% inspection available. Special tooling for molybdenum's unique machining characteristics.

Custom solutions: Special shoulder diameters, non‑standard shoulder lengths, proprietary drives, and tailored packaging. In-house metallurgical laboratory and failure analysis capabilities. Prototype to production volumes supported. Cleanroom wash and packaging available for sensitive applications.

Contact the molybdenum shoulder bolt experts

Request a quotation for molybdenum shoulder bolts, stripper bolts – any standard (ASME B18.3, ISO 7378, NASM 5160) – any grade (Pure Mo, TZM, MoLa) – any condition (stress relieved, recrystallized), any quantity. Global delivery. Mechanical data in MPa/ksi available for all products.

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

Our team provides technical support in English, German, Mandarin, Japanese.

Request A Quote! We'll respond as soon as possible(within 12 hours)