A Ni-Cu alloy with high strength and good corrosion resistance

Flat Head

Strength & Saltwater Resistance
Monel® socket head cap screws are made from a nickel-copper alloy that exhibits high strength, toughness and good corrosion resistance. Renowned for the saltwater corrosion resistance, Monel is the go-to material by the navy. It is often used in many other marine applications for its combination of high strength and seawater resistance. Monel screws are even resistant to rapid moving seawater and will last many years in saltwater conditions.
 
Strength and Toughness from Cryogenic to 1000°F
Monel socket head cap screws offer excellent mechanical properties over a wide temperature range from cryogenic up to 1000°F. In US Navy tear tests at temperatures as low as -320°F, Monel 400 has displayed excellent ductility and toughness. In fact, it has shown little decrease in impact resistance when tested on plates at liquid-hydrogen and liquid-helium temperatures.
 
Monel K500 is an age hardened alloy, known for extreme strength even at high temps. But it is also excellent for cryogenic service. Monel K500's tensile and yield strength increase - with little or no change to ductility and toughness - even at the temperature of liquid hydrogen.
 
Excellent Resistance to Hydrofluoric Acid
One of the most outstanding characteristics of Monel socket head cap screws is that they offer exceptional resistance to hydrofluoric acid (HF), a particularly tough acid to deal with, in all concentrations up to the boiling point. For hydrofluoric acid applications Monel screws are perhaps the most resistant of all commonly used specialty alloys.

The most common grades of Monel nickel alloy screws are Monel 400 and Monel K500 . Gain more insight on these two grades by accessing our Monel 400 and K500 overviews or by contacting our engineering experts.

ResourcesMonel Torque Spec, Flange DimensionsFlange Bolting ChartMonel 400Monel K500

Screw Types12 Point ScrewsButton Head Cap ScrewsFlat Head ScrewsHex Cap ScrewsPan Head ScrewsSet ScrewsSocket Head Cap ScrewsTamper Resistant Security Screws, Torx Screws


Monel Flat Head Screw Features and Benefits

Monel flat head screws are characterized by having a head with a top flat surface (which can feature either a slotted, phillips or allen driver) and bottom that is cone shaped or countersunk. With this design, the head of the screw can align flush or below the surrounding surface having obvious benefits.

Monel Slotted vs. Phillips Driver 

 Slotted Head Advantages Phillips Head Advantages 
  • Slotted head screws tend to strip less than Philips, especially in harsh environments
  • Slotted heads are typically better in applications where it's going to be unscrewed and re-done periodically, as the head tends to wear less.

  • In dirty environments, a flat head is much easier to clean out

  • Phillips head offers a much stronger joint since it can tolerate more torque.

Countersink Angle

For most flat head screw designs the angle of countersink is usually 82° for UNC and UNF applications however other angles ranging from 60° -120° could be specified. 

Thread Type Normal Flat Head Countersink Angle

UNC / UNF

82°

Aerospace 100°
ISO Metric / Imperial 90°

 


Common Grades of Monel Screws

Monel 400 

Monel 400, UNS N04400 (QQ-N-281), is a nickel-copper alloy with high strength and excellent corrosion resistance in a range of media including sea water, hydrofluoric acid, sulfuric acid, and alkalies. Monel 400 is commonly in marine engineering, chemical and hydrocarbon processing applications.

Monel 400 Specifications: BS3075NA13 (Wire), BS3076NA13 (Bar), ASTM B 164 (Rod, Bar, and Wire), ASTM B 564 (Forgings), ASME SB 164 (Rod, Bar, and Wire), ASME SB 564 (Forgings), AECMA PrEN 2305 (Wire for Rivets), SAE AMS 4675 (Bars and Forgings), SAE AMS 4730 (Wire), SAE AMS 4731 (Wire and Ribbon), DIN 17752 (Rod and Bar), DIN 17753 (Wire), DIN 17754 (Forgings), VdTÜV 263 (Sheet, Plate, Bar, and Tubing), QQ-N-281 (Plate, Sheet, Strip, Bar, Rod, Wire, and Forgings), Werkstoff 2.4360

Monel 400 Chemistry

Monel K500 

Monel K500, UNS N05500 (QQ-N-286),  is a precipitation-hardenable nickel-copper alloy that combines the corrosion resistance of Monel alloy 400 with greater strength (over 2x as strong) and hardness. It also has low permeability and is nonmagnetic to temperatures as low as -150°F (-101°C). 

Monel K500 Specifications: BS3075NA18 (Wire), BS3076NA18 (Rod and Bar), ASTM B 865 (Rod and Bar), DIN 17752 (Rod and Bar), DIN 17753 (Wire), DIN 17754 (Forgings), QQ-N-286 (Rod, Bar, Wire, and Forgings), SAE AMS 4676 (Rod and Bar), ASME Code Case 1192 (Rod and Bar), ISO 9723 (Bar), ISO 9724 (Wire), ISO 9725 (Forgings), Werkstoff 2.4375

Monel K500 Chemistry

 


 Mechanical Properties of Monel

Monel 400 Tensile Curves         Monel alloy K500 Tensile Data

Tensile Chart Updated 9 12 18   Monel K500 Tensile Data


 

Monel 400 Corrosion Data

Monel HF vs Nickel Alloys revised

Monel 400 HF IsoCorrosion Curve

 

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