| Visual ID | Description | Material | Tensile Strength |
 |
No lines Unmarked Intermediate Quality SAE Grades 0-1-2 |
Low Carbon Steel | 65,000 p.s.i. |
 |
3 Lines - Common commercial quality Automotive and AN Bolts SAE Grade 5 |
Med. carbon steel Tempered |
120,000 p.s.i. |
 |
4 Lines - Medium commercial quality Automotive and AN Bolts SAE Grade 6 |
Med. carbon steel Quenched & tempered |
140,000 p.s.i. |
 |
5 Lines - rarely used SAE Grade 7 |
Med. carbon alloy steel |
140,000 p.s.i. |
 |
6 Lines - Best commercial quality N.A.S. & Aircraft SAE Grade 8 |
Med. carbon alloy steel Quenched and tempered |
150,000 p.s.i. |
 |
Supertanium | Special alloy steel Quenched & tempered |
160,000 p.s.i. |
 |
A-354-BD A490 |
Med. Carbon alloy steel Quenched & tempered |
150,000 p.s.i. |
 |
Socket head cap screw Also N.A.S. Aircraft standard |
High carbon Quenched & tempered |
160,000 p.s.i. |
 |
N.A.S. 144 Aircraft standard steel |
High carbon Quenched & tempered |
160,000 p.s.i. |
 |
N.A.S. 624 National aircraft standard steel |
High carbon Quenched & tempered |
180,000 p.s.i. |
 |
Aircraft No number assigned steel |
High carbon Quenched & tempered |
220,000 p.s.i. |