We take cryptocurrency — so the coins you hold can buy real hardware.Pay in crypto, spend it on real hardware. Free insured shipping worldwide over $399. Plain, unbranded boxes, sent from Germany.Free insured shipping over $399. Your rate is locked for 30 minutes once checkout opens.Rate locked 30 minutes. Every item sealed, serial-checked and covered by a 24-month warranty.Sealed, 24-month warranty.

Saved items Sign in
Box of 100 black oxide alloy steel socket head cap screws 5/16-18 x 2.5 in

Kerr Lakeside

Kerr Lakeside 31C250KCS .31-18 x 2.5 in. Socket Head Cap Screw Alloy Steel Black Oxide 100 Pieces

SKU CH-30CK-BTXVX

Box of 100 alloy-steel socket head cap screws with black oxide finish, 5/16-18 UNC thread and 2.5 in. length

  • Alloy steel delivers 180,000 psi tensile strength
  • Black oxide finish resists corrosion in harsh environments
  • Hex socket drive enables high-torque installation
  • Coarse UNC threads provide secure grip under vibration
  • 100-piece bulk pack reduces reorder frequency

Threaded Fastener For Industrial Assembly

These alloy steel socket head cap screws use a 5/16-18 UNC coarse thread with a 2.5 in. partial thread length. The black oxide finish adds mild corrosion resistance. A 100-piece pack supports production runs and maintenance kits.

Load Behaviour Over Extended Use

Rated at 180000 lbs/in. tensile strength and a Rockwell hardness of Rc 38-43, the screws maintain clamping force under sustained vibration and thermal cycling. The hex drive distributes torque evenly to reduce rounding during repeated installation or removal cycles.

Coarse Thread Pitch Determines Fit

The 18 threads per inch UNC coarse pitch controls engagement speed and resistance to stripping in softer materials. Buyers who need a fine thread pitch for thinner walls or higher vibration resistance should verify compatibility before ordering.

How it compares

Measured against everything we stock in Bits, Hole Saws & Accessory Kits, at today’s prices. Recalculated every night.

Price $37.99
Pricier than about 60% of the 5,493 comparable items (median $27.99).

Specifications

Product
Brand nameProspect Fastener

Questions about this item

How much heat does a 5/16-18 x 2.5 in. alloy steel socket head cap screw generate under continuous load?

These fasteners are passive components with no moving parts or electrical resistance, so they produce no measurable heat during operation.

What drive tool is required to install the hex socket head on these 5/16-18 coarse-thread screws?

A hex key or hex bit matching the internal drive size for a 5/16-18 socket cap screw is needed; the pack contains 100 pieces with a black oxide finish.

Will the Rc 38-43 hardness of these 180000 psi tensile strength screws damage older tapped holes in softer metals?

The alloy steel screws are significantly harder than aluminium or mild steel, so existing threads in softer materials may strip if overtightened.

More in Bits, Hole Saws & Accessory Kits

Similar items