10B21 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.
10B21
Carbon Steel
10B21 is a boron-treated cold-heading steel: a trace of boron multiplies the hardenability of a 0.20% carbon steel, letting fasteners reach property classes 8.8–10.9 after quenching and tempering. It is supplied as wire rod and wire for high-volume bolt production.
Standards: AISI 10B21 · GB ML10B21 family (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 | 10B21 | SAE 1020 |
|---|---|---|
| C | 0.18–0.23 | 0.18–0.23 |
| Mn | 0.70–1.00 | 0.30–0.60 |
| P | ≤0.035 | ≤0.040 |
| S | ≤0.035 | ≤0.050 |
| B | 0.0005–0.003 | — |
Properties compared
| Property | 10B21 | SAE 1020 |
|---|---|---|
| Tensile strength | 800–1050 MPa (Q&T fastener duty, property class 8.8–10.9 range) | 380–450 MPa (hot rolled) |
| Density | 7.85 g/cm³ | 7.85 g/cm³ |
| Yield strength | — | ≥245 MPa |
| 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: 10B21 · SAE 1020. Substitution decisions for certified parts stay with the design authority.