STKM13A vs SAE 1020
These two grades are listed as equivalents of each other: their chemistry windows overlap and they serve the same applications. They are not always identical — check the differences below before substituting, especially in certified designs.
STKM13A
Pipe & Tube Steel
STKM13A is a JIS G3444 carbon steel tube for machine structural purposes — the 370 MPa class tube Japanese machinery makers use for frames, rollers and mechanical parts. Its chemistry window mirrors STPG370 but the standard, tolerances and flattening/flaring tests are written for mechanical tube, not pressure pipe.
Standards: DIN E235 tube type (near) · AISI 1020 tube type (near) · JIS STKM13A (JIS G3444) · GB 20 tube (near)
SAE 1020
Carbon Steel
SAE 1020 is a low-carbon steel for general engineering: easily machined, formed and welded, and the default material for low-load shafts, pins and seamless tube in carbon grade.
Standards: DIN 1.0402 (C22) · AISI 1020 · JIS S20C · GB 20
Chemical composition compared (%)
| Element | STKM13A | SAE 1020 |
|---|---|---|
| C | ≤0.25 | 0.18–0.23 |
| Si | ≤0.35 | — |
| Mn | 0.30–0.90 | 0.30–0.60 |
| P | ≤0.040 | ≤0.040 |
| S | ≤0.040 | ≤0.050 |
Properties compared
| Property | STKM13A | SAE 1020 |
|---|---|---|
| Tensile strength | ≥370 MPa | 380–450 MPa (hot rolled) |
| Yield strength | ≥215 MPa | ≥245 MPa |
| Density | 7.85 g/cm³ | 7.85 g/cm³ |
| Product form | Carbon steel tube for machine structural use (JIS G3444) | — |
| Weldability | — | Excellent |
Sourcing either grade?
Nasteel stocks both families from Shenzhen with EN 10204 3.1 mill certificates by heat number.
Ask for a quotationSee full data sheets: STKM13A · SAE 1020. Substitution decisions for certified parts stay with the design authority.