When extreme high temperature stability & strength are required

Molybdenum hex head cap screws possess 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 hex head cap screws to oxygen above 600°C will cause them to readily oxidize.

As a result, molybdenum hex head cap screws find their way into high temperature vacuum furnaces, glass production, military and space applications where oxygen is not present.

ResourcesMolybdenum Torque Spec

Screw TypesButton Head Cap ScrewsFlat Head ScrewsHex Cap ScrewsPan Head ScrewsSet ScrewsSocket Head Cap Screws

 


Molybdenum Hex Head Cap Screw Features and Benefits

It is important to differentiate between a molybdenum hex head cap screw and hex head bolt. Often people assume they are the same, but they are actually very different fasteners in terms of how they are manufactured, as well as from an application perspective. Regardless of your choice, molybdenum hex heads offer strong, stable joints because of their large head service.

The Hex Comparison

Hex Head Cap Screw Hex Head Bolts
  • Precise applications where tight tolerances on the body dimensions are required. 
  • Features flat washer facing under the bolt head.
  • Also called a finished hex bolt.
  • Appropriate for when mechanical properties are more important than dimensional tolerances. 
  • Hex bolts have a flat end and lack the washer face under the head.

Molybdenum Hex Head Cap Screw Advantages  

The most important feature of a molybdenum hex head cap screws is that it has a larger bearing surface area which provide better clamping pressure than other type of fastener such as a socket head cap screw. Additionally, since debris build up is less of an issue with this style of fastener verses a socket head cap screw, they are ideal of dirty applications where particles could clog up a socket. Though molybdenum socket heads are typically used for tight access applications, hex heads can be a better choice when there is only side clearance available for tightening. 

 


Common Molybdenum Screw Grades and Specs

Molybdenum (Commercially Pure)

Because of its high melting point of 2620C and its good strength, pure molybdenum finds it niche in high temperature vacuum or inert environments without oxygen.

Molybdenum Specifications: ASTM B386, ASTM B387, Type 361

Molybdenum Chermistry

TZM - Titanium / Zirconium / Molybdenum Alloy

This alloyed version of molybdenum provides enhanced strenght at elevated temperatures and is excellent for support structures in vacuum furnaces or other high temperatuer and oxygen free environments. 

TZM Specifications: UNS R03630, ASTM B384, ASTM B385, ASTM B386, ASTM B387

TZM Chemistry

 


Mechanical Properties

Molybdenum Tensile Curves

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