A Ni-Cr alloy with very good high temperature stability

Not to be confused with Inconel, Incoloy flat head screws are made of a nickel alloy which contains iron and a lower content of nickel. Incoloy is essentially a more economical option to Inconel, yet with more restricted corrosion resistance and temperature limits. Typically, Incoloy is an ideal material for long-term exposure in high temperature environments due to its oxidation, carburization and creep resistance. Incoloy is widely used for its resistance to seawater, brine, sour gas and high chloride environments at elevated temperatures, which make it a popular choice in the oil and gas and power industries. 

The most commonly used grades of Incoloy screws are Incoloy 800, 800H, 800HTIncoloy 825; and Incoloy 925. For more indepth information on these specific grades, visit our specific web pages or contact one of our engineering experts:

ResourcesIncoloy Torque SpecsFlange DimensionsFlange Bolting Chart

Incoloy Fastener Types: BoltsNutsScrewsThreaded RodsWashers

Screw Types Available:  12 Point ScrewsButton Head Cap ScrewsFlat Head ScrewsHex Head Cap ScrewsPan Head ScrewsSet ScrewsSocket Head Cap ScrewsTamper Resistant Security Screws, Torx ScrewsVented Screws


Incoloy Flat Head Screw Features and Benefits

Incoloy 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.

Incoloy 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 Incoloy Chemistry, Grades & Specifications

Incoloy 800, 800H, H00HT

Incoloy 800 series screws are best utilized for applications that require stable structure and good strength during prolonged exposure to high temperatures. 

Incoloy 800, 800H & 800HT Specifications: UNS N08800/ N08810 / N08811 (800, 800H, 800HT), ASTM B408, ASME SB408, ASTM B564/ASME SB564, EN 10204-3.1, Werkstoff 1.4876 (800), Werkstoff 1.4876 H and 1.4958 (800H), Werkstoff 1.4876 HT and 1.4959 (800HT)

 Incoloy 800 Chemistry

Incoloy 825

Related to the Incoloy 800 series alloys, Incoloy 825 differentiates itself with the additional elements of molybdenum and copper, which provides it improved corrosion resistance. 

Incoloy 825 Specifications: UNS N08825, , BS 3076NA16, ASTM B 425, ASTM B 564, ASME SB 425, ASME SB 564, ASME Code Case N-572, DIN 17752, DIN 17753, DIN 17754, VdTÜV 432, ISO 9723, ISO 9724, ISO 9725, Werkstoff Nr 2.4858

Incoloy 825 Chemistry

Incoloy 925

Incoloy 925 is a precipitation hardened alloy. It offers comparable corrosion resistance to it’s sister alloy Incoloy 825, but with the increased strength resulting from the age hardening process. 

Incoloy 925 Specifications: UNS N09925, ASTM B637, NACE MR0175 Incoloy 925 Chemistry 


Mechanical Properties of Incoloy

Incoloy 800 Tensile Curve

Incoloy 825 Tensile Curve

  

Incoloy 925 Tensile Curve Aged

 

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