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A307 Hex Bolt, Galvanized

Selected A307 Grade A Finish Hex Bolt Hot Dipped GalvanizedA307 Hex Bolt, Galvanized
A307 Grade A Finish Hex Bolt Hot Dipped GalvanizedA307 Hex Bolt, Galvanized

ASTM A307 Grade A hex bolts are common fasteners manufactured from low carbon steel. Dimensional specifications are governed by ASME B18.2.1. Grade marking consists of both the grade symbol "307A" and the manufacturer's identification mark. Inch series fasteners meeting ASTM A307 Grade A specifications are common/economical fasteners used for general applications. These bolts have a finished pattern head, whereas A307 Grade B bolts have a heavy pattern head. A307 hex bolts are available in hot dip galvanized finish, which provides a corrosion resistant zinc coating.

Products

Mechanical Properties

Low Carbon Steel Per ASTM A307-2014
Grade A Diameter Bolt or Stud Length Tensile Strength Elongation Core Hardness (1)
Min psi Min % Rockwell
1/4 thru 4" Less than 3 X dia (2) 60,000 18 B69 to B100
3 X dia and longer 60,000 18 B100
  1. 1. As measured anywhere on the surface or through the cross section.
  2. 2. Also bolts with drilled or undersized heads. These sizes and bolts with modified heads shall meet the minimum and maximum hardness as hardness is the only requirement.

Governing Standards

ASTM A307 Covers the mechanical and material requirements for inch series fasteners in diameters from 1/4″ through 4″, made of carbon steel having a minimum tensile strength of 60,000 psi.
ASME B18.2.1 Covers the complete general and dimensional data for multiple types of inch series square and hex bolts and screws.
ASME B1.1 UNC & UNF Class 2A Specifies the thread form, series, class, allowance, tolerance, and designation for unified screw threads.

A307 Head Marking
A307 Material Marking

Chemical Properties

Per ASTM A307-2014
Grade A Carbon Manganese Phosphorus Sulfur
% by heat   analysis % by heat analysis % by heat analysis % by heat analysis
0.29 1.20 0.04 0.15

Dimensional Specifications

Finished bolt and cap screw dimensions
Per ASME B18.2.1-2012
Nominal Diameter UNC UNF E F G H LT
Body Diameter Width Across Flats Width Across Corners Head Height Thread Length
Max Min Basic Max Min Max Min Basic Max Min Lengths up to 6" Lengths > 6"
1/4 0.2500 20 28 0.2500 0.2405 7/16 0.4380 0.4280 0.5050 0.4880 5/32 0.1630 0.1500 0.7500 1.0000
5/16 0.3125 18 24 0.3125 0.3065 1/2 0.5000 0.4890 0.5770 0.5570 13/64 0.2110 0.1950 0.8750 1.1250
3/8 0.3750 16 24 0.3750 0.3690 9/16 0.5620 0.5510 0.6500 0.6280 15/64 0.2430 0.2260 1.0000 1.2500
7/16 0.4375 14 20 0.4375 0.4305 5/8 0.6250 0.6120 0.7220 0.6980 9/32 0.2910 0.2720 1.1250 1.3750
1/2 0.5000 13 20 0.5000 0.4930 3/4 0.7500 0.7360 0.8660 0.8400 5/16 0.3230 0.3020 1.2500 1.5000
9/16 0.5625 12 18 0.5625 0.5545 13/16 0.8120 0.7980 0.9380 0.9100 23/64 0.3710 0.3480 1.3750 1.6250
5/8 0.6250 11 18 0.6250 0.6170 15/16 0.9380 0.9220 1.0830 1.0510 25/64 0.4030 0.3780 1.5000 1.7500
3/4 0.7500 10 16 0.7500 0.7410 1 1/8 1.1250 1.1000 1.2990 1.2540 15/32 0.4830 0.4550 1.7500 2.0000
7/8 0.8750 9 14 0.8750 0.8660 1 5/16 1.3120 1.2850 1.5160 1.4650 35/64 0.5630 0.5310 2.0000 2.2500
1 1.0000 8 14 1.0000 0.9900 1 1/2 1.5000 1.4690 1.7320 1.6750 39/64 0.6270 0.5910 2.2500 2.5000
1 1/8 1.1250 7 12 1.1250 1.1140 1 11/16 1.6880 1.6310 1.9490 1.8590 11/16 0.7180 0.6580 2.5000 2.7500
1 1/4 1.2500 7 12 1.2500 1.2390 1 7/8 1.8750 1.8120 2.1650 2.0660 25/32 0.8130 0.7490 2.7500 3.0000
1 3/8 1.3750 6 12 1.3750 1.3630 2 1/16 2.0620 1.9940 2.3820 2.2730 27/32 0.8780 0.8100 3.0000 3.2500
1 1/2 1.5000 6 12 1.5000 1.4880 2 1/4 2.2500 2.1750 2.5980 2.4800 15/16 0.9740 0.9020 3.2500 3.5000
  1. All dimensions are in inches.
  2. Usable thread length for Hex Head Cap Screws under 6 1/4" long can be approximated by the equation THREAD LENGTH = (2 X DIAMETER) + 1/4″