An extremely strong precipitation hardened stainless steelFlat Head

17-4 PH flat head screws are made from a precipitation hardened stainless steel most known for its exceptional strength and its ability to maintain its mechanical properties to 600°F. Compared to 316 stainless steel, 17-4 PH flat head screws yield strength is up over 4 times greater. When compared to Duplex 2205 screws, the yield strength of 17-4 PH can be up to 2-½ times greater.

17-4 screws are available in 8 different aged (precipitation hardened) conditions offering a variety of mechanical properties (see below). 

Resources: 17-4PH Torque Specs

17-4 PH Screw Types: 12 Point ScrewsButton Head Cap ScrewsFlat Head ScrewsHex Cap ScrewsPan Head ScrewsSet ScrewsSocket Head Cap ScrewsTamper Resistant Security Screws, Torx Screws, Vented Screws


17-4PH Flat Head Screw Features and Benefits

17-4PH 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.

17-4PH 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°

 


17-4PH Chemistry & Specifications

17-4PH Specifications: UNS S17400, AISI 630, ASTM A564-630, Werkstoff 1.4542, AMS 5604 Sheet, Strip and Plate, ASTM A 693 Plate

17 4 PH Chemistry

ASTM F593, Grade 630
This specification covers seven groups of stainless steel alloys, with ASTM F593, Grade 630 applying 17-4PH. ASTM F593 Grade 630 covers the requirements for 17-4PH stainless steel bolts, hex cap screws, and studs sized 0.25 to 1.50 inches, inclusive, in nominal diameter. It is intended for common use and for service applications requiring general corrosion resistance.

ASTM F593 Grade 660 chart B


Common 17-4 Fastener Conditions:  Aged Conditions vs Tensile Strength

ASTM A564 GR 630
This specification covers bars and shapes (such as fasteners) of age hardened stainless steels such as 17-4PH. It includes hot-finished or cold-finished fasteners that are produced by hot rolling, extruding, or forging. Grade 630 shall be furnished in the solution-annealed or or age-hardened condition.

Tensiled Data vs Aged Condition Updated 7 2021

 

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