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General Structural Steel Spec Table
General Structural Steel KS Specifications — 2 sizes
KS D 3503
General structural steel represented by SS400, most widely used for buildings, machine frames, and brackets.
Practical Notes
- SS400 guarantees ≥400MPa tensile strength but has loose chemical composition requirements. Good weldability, but use S45C for heat treatment applications.
- Specify "SS400" or "general structural" on drawings. Vague "steel" callouts lead each shop to use different materials.
KSGeneral Structural Steel
2 sizes| Name | Type | Tensile | Yield | Hardness | Use |
|---|---|---|---|---|---|
| SS400 | General Mild Steel | 400~510 | ≥245 | HB120~160 | General Structure, Shaft, MachineParts, WeldStructure |
| SS490 | General Mild Steel | 490~610 | ≥285 | HB140~180 | Bridge, Ship, Vehicle, High Strength Structure |
Key Features
- SS400 (tensile 400–510 MPa); excellent general workability: welding, cutting, bending
- KS D 3503; supplied as plates, sections, and bars; basic structural material for construction/machinery
- Carbon content unspecified (no chemical composition requirement); only mechanical properties guaranteed
Key Applications
Building steelwork, machine frames, brackets, base plates, guardrails
FAQ
What is SS400 yield strength?
About 235–245MPa (varies by thickness). Tensile strength 400–510MPa is guaranteed; yield strength is not guaranteed but typically designed at ~235MPa.