Hex Head Cap Screws are designed for easy assembly into a tapped hole. Hex Cap Screws meet SAE specifications with a specially designed washer face under the head and a chamfered point. Grade 5 is the most common grade used in manufacturing assembly. Zinc plating, retards the corrosion rate in a normal atmosphere. Tensile Strength: 120,000 psi minimum.
Download the spec table as a PDF: Grade Specs
US Bolts |
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| Head Marking | Grade and Material |
Nominal Size Range (inches) |
Mechanical Properties | ||
|---|---|---|---|---|---|
| Proof Load (psi) |
Min. Yield Strength (psi) |
Min. Tensile Strength (psi) |
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 No Markings |
Grade 2Low or medium carbon steel |
1/4 thru 3/4 | 55,000 | 57,000 | 74,000 |
| Over 3/4 thru 1-1/2 | 33,000 | 36,000 | 60,000 | ||
 3 Radial Lines |
Grade 5Medium carbon steel, quenched and tempered |
1/4 thru 1 | 85,000 | 92,000 | 120,000 |
| Over 1 thru 1-1/2 | 74,000 | 81,000 | 105,000 | ||
 6 Radial Lines |
Grade 8Medium carbon alloy steel, quenched and tempered |
1/4 thru 1-1/2 | 120,000 | 130,000 | 150,000 |
| Stainless markings vary. Most stainless is non-magnetic |
18-8 StainlessSteel alloy with 17-19% Chromium and 8-13% Nickel |
All Sizes thru 1 | 20,000 Min. 65,000 Typical | 65,000 Min. 100,000 – 150,000 Typical | |
Metric Bolts |
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| Head Marking | Class and Material |
Nominal Size Range (mm) |
Mechanical Properties | ||
| Proof Load (MPa) |
Min. Yield Strength (MPa) |
Min. Tensile Strength (MPa) |
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Class 8.8Medium carbon steel, quenched and tempered |
All Sizes below 16mm | 580 | 640 | 800 |
| 16mm – 72mm | 600 | 660 | 830 | ||
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Class 10.9Alloy steel, quenched and tempered |
5mm – 100mm | 830 | 940 | 1040 |
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Class 12.9Alloy steel, quenched and tempered |
1.6mm – 100mm | 970 | 1100 | 1220 |
| Stainless markings vary. Most stainless is non-magnetic. Usually stamped A-2. |
A-2 StainlessSteel alloy with 17- 19% chromium and 8-13% nickel |
All Sizes thru 20mm | 210 Min. 450 Typical |
500 Min. 700 Typical |
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| Tensile Strength: The maximum load in tension (pulling apart) which a material can withstand before breaking or fracturing.
Yield Strength: The maximum load at which a material exhibits a specific permanent deformation Proof Load: An axial tensile load which the product must withstand without evidence of any permanent set. 1MPa = 1N/mm2 = 145 pounds/inch2 |
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