ASME/ANSI B18.3 Hexagon Socket Head Cap Screws
ASME/ANSI B18.3 Hexagon Socket Head Cap Screws feature a cylindrical head with a recessed hexagon socket, providing a compact fastening solution where conventional external-head bolts may require more installation space. The internal hex drive allows the screw to be tightened from above with an Allen-type wrench, making it suitable for assemblies where access around the fastener head is limited.
The socket head design provides a relatively small head diameter while maintaining a substantial bearing area and robust head section. This makes Socket Head Cap Screws well suited to machine components, tooling, fixtures, equipment assemblies, and other compact mechanical connections where strength and space efficiency are important. For selection, customers should consider the nominal diameter, screw length, thread series, material, strength grade, hardness, surface finish, and available tool access to ensure the screw matches both the joint requirements and installation conditions.
Specification:
| Item | Specification |
|---|---|
| Standard | ASME/ANSI B18.3 |
| Product Type | Hexagon Socket Head Cap Screw |
| Head Style | Cylindrical Head |
| Drive Type | Hexagon Socket/Internal Hex |
| Thread System | Inch |
| Thread Series | UNC/UNF |
| Size Range | #0-1/2" |
| Material | Alloy Steel, Stainless Steel |
| Alloy Steel Standard | ASTM A574 |
| Stainless Steel Standard | ASTM F837 |
| Surface Treatment | Plain,Zinc Plated,Black Oxidation,Bright Finish,Passivation |
Dimension Chart:
| Mon | #0 | #1 | #2 | #3 | #4 | #5 | #6 | #8 | #10 | 1/4 | 5/16 | 3/8 | 7/16 | 1/2 | 5/8 | 3/4 |
| P | 80 | 64|72 | 56|64 | 48|56 | 40|48 | 40|44 | 32|40|48 | 32|36 | 24|32 | 20|28|32 | 18|24|32 | 16|24|32 | 14|20|28 | 13|20|28 | 11|18|24 | 10|16|20 |
| dk max | 0.096 | 0.118 | 0.14 | 0.161 | 0.183 | 0.205 | 0.226 | 0.27 | 0.312 | 0.375 | 0.469 | 0.562 | 0.656 | 0.75 | 0.938 | 1.125 |
| dk min | 0.091 | 0.112 | 0.134 | 0.154 | 0.176 | 0.198 | 0.216 | 0.257 | 0.298 | 0.354 | 0.446 | 0.54 | 0.631 | 0.725 | 0.914 | 1.094 |
| k max | 0.06 | 0.073 | 0.086 | 0.099 | 0.112 | 0.125 | 0.138 | 0.164 | 0.19 | 0.25 | 0.312 | 0.375 | 0.438 | 0.5 | 0.625 | 0.75 |
| k min | 0.057 | 0.07 | 0.083 | 0.095 | 0.108 | 0.121 | 0.134 | 0.159 | 0.185 | 0.244 | 0.306 | 0.368 | 0.43 | 0.492 | 0.616 | 0.74 |
| s | 0.05 | 0.062 | 0.078 | 0.078 | 0.094 | 0.094 | 0.109 | 0.141 | 0.156 | 0.188 | 0.25 | 0.312 | 0.375 | 0.375 | 0.5 | 0.625 |
| t min | 0.025 | 0.031 | 0.038 | 0.044 | 0.051 | 0.057 | 0.064 | 0.077 | 0.09 | 0.12 | 0.151 | 0.182 | 0.213 | 0.245 | 0.307 | 0.37 |
Mechanical Property:
1. ASTM A574 – Alloy Steel Socket-Head Cap Screws
ASTM A574 specifies the mechanical and material requirements for quenched and tempered alloy steel hexagon socket head cap screws. It covers tensile strength, proof load, yield strength, elongation, and hardness requirements to ensure the strength and reliability of socket head cap screws in demanding fastening applications.
2. ASTM F837 – Stainless Steel Socket-Head Cap Screws
ASTM F837 specifies the requirements for stainless steel hexagon socket head cap screws, covering different stainless steel alloy groups and conditions. It establishes mechanical property requirements, including tensile strength, yield strength, elongation, and hardness, depending on the material group and condition.