validation of the strength of the bolt. However, low-cost fasteners may be found with actual strength far less than indicated by the markings. Such inferior fasteners are a danger to life and property when used in aircraft, automobiles, heavy trucks, and similar applications. Inch defines the bolt grades for inch-system sized bolts and screws. It defines them by grade, which ranges from 0 to 8, with 8 being the strongest. Higher grades do not exist within the specification. SAE grades 5 and 8 are the most common. []Head markings and properties for inch-system hex-head cap screws Head Grade, material, Nominal Proof Yield Tensile Core marking and condition size strength strength, strength, hardness range (in) (ksi/MPa) min. min. () (ksi/MPa) (ksi/MPa) SAE Grade 0 Strength and hardness is not specified SAE grade 1 33/230 60/410 B70–100 1⁄4–1-1⁄2 ASTM A307 Low carbon steel ASTM A307 - 60/410 B69–95 1⁄4–4 Grade B minimum Low or medium 100/690 carbon steel maximum SAE grade 2 55/380 57/390 74/510 B80–100 1⁄4–3⁄4 Low or medium Greater 33/230 36/250 60/410 B70–100 carbon steel than 3⁄4 SAE grade 4 100/690 115/790 1⁄4–1-1⁄2 Medium carbon steel; cold worked SAE grade 3 85/590 100/690 B70–100 1⁄4–1 Medium carbon steel; cold worked SAE grade 5 85/590 92/630 120/830 C25–34 1⁄4–1 Medium carbon (inc.) steel; quench and 1–1-1⁄2 74/510 81/560 105/720 C19–30 tempered ASTM A449 - Type 1–1-1⁄2 74/510 105/720 C19–30 1 (inc.) Medium carbon 1-1⁄2–3 55/380 90/620 183–235 steel; quench and tempered SAE grade 5.1 No. 6–1⁄2 85/590 120/830 C25–40 Low or medium carbon steel; quench and tempered
validation of the strength of the bolt. However, low-cost fasteners may be found with actual strength far less than indicated by the markings. Such inferior fasteners are a danger to life and property when used in aircraft, automobiles, heavy trucks, and similar applications. Inch defines the bolt grades for inch-system sized bolts and screws. It defines them by grade, which ranges from 0 to 8, with 8 being the strongest. Higher grades do not exist within the specification. SAE grades 5 and 8 are the most common. []Head markings and properties for inch-system hex-head cap screws Head marking Grade, material, and condition Nominal size range (in) Proof strength (ksi/MPa) Yield strength, min. (ksi/MPa) Tensile strength, min. (ksi/MPa) Core hardness () SAE Grade 0 Strength and hardness is not specified SAE grade 1 ASTM A307 Low carbon steel 1⁄4–1-1⁄2 33/230 60/410 B70–100 ASTM A307 - Grade B Low or medium carbon steel 1⁄4–4 60/410 minimum 100/690 maximum B69–95 SAE grade 2 Low or medium carbon steel 1⁄4–3⁄4 55/380 57/390 74/510 B80–100 Greater than 3⁄4 33/230 36/250 60/410 B70–100 SAE grade 4 Medium carbon steel; cold worked 1⁄4–1-1⁄2 100/690 115/790 SAE grade 3 Medium carbon steel; cold worked 1⁄4–1 85/590 100/690 B70–100 SAE grade 5 Medium carbon steel; quench and tempered 1⁄4–1 (inc.) 85/590 92/630 120/830 C25–34 1–1-1⁄2 74/510 81/560 105/720 C19–30 ASTM A449 - Type 1 Medium carbon steel; quench and tempered 1–1-1⁄2 (inc.) 74/510 105/720 C19–30 1-1⁄2–3 55/380 90/620 183–235 SAE grade 5.1 Low or medium carbon steel; quench and tempered No. 6–1⁄2 85/590 120/830 C25–40
8b%20WIKIPEDIA_Screws.docx