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Allen Socket Head Bolt

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Stainless Steel Allen Socket Head Bolt - Grade 202, 304, 316, A2, A2-70

Allen Socket Head Bolts, also known as Socket Head Cap Screws, are precision fasteners designed for applications requiring high strength and compact installation space. The cylindrical head with an internal hexagonal socket allows high torque tightening using an Allen key, making them ideal for machinery, automotive assemblies, tooling fixtures, and structural components. Gemstar Allen bolts are manufactured using premium stainless steel and high-tensile alloy steel, ensuring excellent durability, corrosion resistance, and long service life even in demanding environments. They are produced in compliance with international standards including DIN 912, ISO 4762, IS 2269, and ANSI/ASME B18.3 , Grade 202, 304, 316 for complete dimensional accuracy and interchangeability.

Key Features

Compact Head Design
Cylindrical Head with an internal hex drive allows use in confined spaces where standard hex bolts cannot reach.
High Torque
Hexagonal socket guarantees high torque and reduce slippage and rounding.
Strength Grades
Available in Stainless Steel grades A2-70,A2-80,A4-70,A4-80 as well in steel grades property Class 8.8 10.9 and 12.9 with a maximum tensile strength of 1220 mega pascals.
Corrosion Resistance
Stainless steel grades offers high corrosion resistance and protective coatings such as HDG, black oxide, and zinc plating ensures protection in steel grades.
Tolerances
Manufactured as per international standards ISO 4762/DIN 912/IS 2269 and ANSI/ASME B18.3 to ensure accuracy and interchangeability.
Threads
Supplied in half thread or full thread to suit strength and grip requirements.

Below are technical specifications for Allen-style socket-head cap screws in both metric (ISO 4762/DIN 912) and imperial (ANSI B18.3.1M) standards. Each table lists key dimensions, thread data, and common strength grades.

Metric (ISO 4762 / DIN 912 / IS 2269)

Size Thread Pitch (P) Head Ø (D) Head Height (k) Hex Socket Across Flats (S)
Length - F/T
Length - H/T
 Avaliable Grades¹
M3 0.5 mm 5.5 mm 3 mm 2.5 mm
10-40
-
A2-70,
A2-80,
A4-70,
8.8,
10.9,
12.9
M4 0.7 mm 7 mm 4 mm 3 mm
10-50
-
M5 0.8 mm 8.5 mm 5 mm 4 mm
10-50
-
M6 1.0 mm 10 mm 6 mm 5 mm
10-100
50-100
M8 1.25 mm 13 mm 8 mm 6 mm
10-120
50-120
M10 1.5 mm 16 mm 10 mm 8 mm
16-130
50-130
M12 1.75 mm 18 mm 12 mm 10 mm
20-150
50-150
M16 2.0 mm 24 mm 16 mm 14 mm
25-150
50-150

BSW (Whitworth Threads)

Size Threads per Inch (TPI) Head Ø (D) Head Height (k) Hex Socket (S) Grades
3/16″ BSW 24 TPI 0.312″ (7.9 mm) 0.187″ (4.8 mm) 5/32″ (4 mm) High Tensile (BS 1936), A2-70, A4-70
1/4″ BSW 20 TPI 0.375″ (9.5 mm) 0.250″ (6.4 mm) 3/16″ (4.8 mm)
5/16″ BSW 18 TPI 0.469″ (11.9 mm) 0.313″ (7.9 mm) 1/4″ (6.4 mm)
3/8″ BSW 16 TPI 0.562″ (14.3 mm) 0.375″ (9.5 mm) 5/16″ (8 mm)
1/2″ BSW 12 TPI 0.750″ (19.1 mm) 0.500″ (12.7 mm) 3/8″ (9.5 mm)
5/8″ BSW 11 TPI 0.938″ (23.8 mm) 0.625″ (15.9 mm) 1/2″ (12.7 mm)
3/4″ BSW 10 TPI 1.125″ (28.6 mm) 0.750″ (19.1 mm) 5/8″ (16 mm)

Imperial (ANSI/ASME B18.3)

Size Threads per Inch (TPI) Head Ø (D) Head Height (k) Hex Socket (S) Grades
1/4″ UNC 20 TPI 0.375″ (9.5 mm) 0.250″ (6.4 mm) 3/16″ (4.8 mm)
ASTM A574 (170 ksi),

A2-70, A4-70
5/16″ UNC 18 TPI 0.469″ (11.9 mm) 0.313″ (7.9 mm) 1/4″ (6.4 mm)
3/8″ UNC 16 TPI 0.562″ (14.3 mm) 0.375″ (9.5 mm) 5/16″ (8 mm)
1/2″ UNC 13 TPI 0.750″ (19.1 mm) 0.500″ (12.7 mm) 3/8″ (9.5 mm)
5/8″ UNC 11 TPI 0.938″ (23.8 mm) 0.625″ (15.9 mm) 1/2″ (12.7 mm)
3/4″ UNC 10 TPI 1.125″ (28.6 mm) 0.750″ (19.1 mm) 5/8″ (16 mm)
1″ UNC 8 TPI 1.500″ (38.1 mm) 1.000″ (25.4 mm) 3/4″ (19 mm)
1/4″ UNF 28 TPI 0.375″ (9.5 mm) 0.250″ (6.4 mm) 3/16″ (4.8 mm)
3/8″ UNF 24 TPI 0.562″ (14.3 mm) 0.375″ (9.5 mm) 5/16″ (8 mm)
1/2″ UNF 20 TPI 0.750″ (19.1 mm) 0.500″ (12.7 mm) 3/8″ (9.5 mm)
3/4″ UNF 16 TPI 1.125″ (28.6 mm) 0.750″ (19.1 mm) 5/8″ (16 mm)

¹ Metric strength classes indicate ultimate tensile strength (UTS) and yield strength.

  • Class 8.8 ≈ 800 MPa UTS / 640 MPa yield
  • Class 10.9 ≈ 1 000 MPa UTS / 900 MPa yield
  • Class 12.9 ≈ 1 220 MPa UTS / 1 100 MPa yield

Stainless steel property classes (ISO 3506-1):

  • A2-70 ≈ 700 MPa UTS / 450 MPa yield
  • A2-80 ≈ 800 MPa UTS / 600 MPa yield
  • A4-70 ≈ 700 MPa UTS / 450 MPa yield (with superior corrosion resistance for marine/chloride environments)
  • A4-80 ≈ 800 MPa UTS / 600 MPa yield
  • Metric (B18.3.1M) → same as ISO 4762 / DIN 912 / IS 2269.
  • UNC/UNF (B18.3) → Inch series, coarse (UNC) and fine (UNF) threads.
  • Strength: ASTM A574 alloy steel (170 ksi UTS ≈ 1,170 MPa, similar to Class 12.9).
  • Stainless available in A2-70, A4-70, A4-80 grades.

Designed to meet the highest industry standards, Our Allen Socket Head Bolts are made with precision, coupled with long-lasting strength. The hexagonal socket design enables the transfer of torque optimally, ensuring dependable and secure fastening, every single time. Whenever there is a need for reliability and strength in a project, our Allen Socket Head Bolts are a preferred choice, as they are designed with dependability in mind, and are trusted across industries.

Mechanical Properties – Class 12.9 Socket Head Cap Screws

Tensile Strength

≥1220 MPa

Yield Strength

≥1100 MPa

Elongation

≥8%

Hardness Max

39-44 HRc

Materials

  • Stainless Steel
  • AISI 202
  • AISI 304
  • AISI 316

Steel Grade

  • 8.8
  • 10.9
  • 12.9

Finishing

  • Polished
  • Geomet
  • Dacromet
  • Teflon
  • Hot-Dip Galvanzing
  • Zinc (Yellow, White, Blue)
  • Black Qxide

Thread

  • Metric
  • BSW
  • UNC
  • UNF

Standards

  • Din 912
  • ISO 4762
  • IS 2269
  • BS 2470 - 1973
  • ASTM F835
  • ASTM A574

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