The SAE International (formerly AISI) classification system provides the most comprehensive steel grading framework for North American industries. These specifications cover all major steel types with precise chemical composition requirements for engineering applications.
Below are the complete classifications of SAE steel grades by fundamental metallurgical categories:
1. Carbon Steels (10XX Series)
- SAE 1006-1018 – Low carbon steels for cold forming and fabrication
- SAE 1020-1045 – Medium carbon steels for machined components
- SAE 1050-1095 – High carbon steels for cutting tools and springs
Basic Composition: Iron + Carbon (0.06%-1.03%) + Manganese
2. Alloy Steels (XXXX Series)
- SAE 41XX – Chromium-molybdenum steels (e.g., 4140, 4150)
- SAE 43XX – Nickel-chromium-molybdenum steels (e.g., 4340)
- SAE 86XX – Nickel-chromium-molybdenum alternative grades
Alloying Elements: Cr, Ni, Mo, V in varying combinations
3. Stainless Steels (3XX/4XX/5XX)
- SAE 3XX – Austenitic (304, 316) – Corrosion resistant
- SAE 4XX – Martensitic/Ferritic (410, 430) – Heat treatable
- SAE 5XX – Precipitation hardening (17-4PH)
4. Tool Steels (Letter-Number System)
- SAE W-Series – Water-hardening (W1, W2)
- SAE O-Series – Oil-hardening (O1, O2)
- SAE A-Series – Air-hardening (A2, A6)
5. Special Application Steels
- SAE 92XX – Silicon-manganese spring steels
- SAE 50BXX – Boron-treated high-strength steels
- SAE 15BXX – Leaded free-machining steels
6. High-Strength Low-Alloy (HSLA)
Key Applications by Steel Type
| Steel Category | Typical Uses | Example Grades |
|---|---|---|
| Carbon | Fasteners, shafts | 1018, 1045 |
| Alloy | Gears, axles | 4140, 4340 |
| Stainless | Chemical tanks | 304, 316 |
| Tool | Dies, cutters | D2, O1 |
| HSLA | Structural | 942X, 945X |
Why SAE Classification Matters
◉ Systematic Coding – Numbering reveals chemistry (e.g., 4140 = Cr-Mo alloy)
◉ Performance Benchmarking – Mechanical properties tied to grade numbers
◉ Heat Treatment Guidance – Hardenability requirements specified
For material selection advice or full SAE specification sheets, request technical documents.