40Mn vs 1040
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.
40Mn
Carbon Steel
40Mn is the GB/T 699 manganese-enhanced version of grade 40 — a low-cost Q&T machinery steel common in Chinese domestic machinery where 1040-class carbon is lifted by extra manganese.
Standards: AISI 1040 type (higher Mn) · GB 40Mn (GB/T 699)
1040
Carbon Steel
1040 is a medium carbon steel for moderately stressed shafts, bolts and gears. It is the plain-carbon predecessor of 5140/40Cr in many cost-sensitive designs, with similar carbon but no chromium hardenability boost.
Standards: DIN 1.0511 (C40) · AISI 1040 · JIS S40C · GB 40
Chemical composition compared (%)
| Element | 40Mn | 1040 |
|---|---|---|
| C | 0.37–0.44 | 0.37–0.44 |
| Si | 0.17–0.37 | — |
| Mn | 0.70–1.00 | 0.60–0.90 |
| P | ≤0.035 | ≤0.040 |
| S | ≤0.035 | ≤0.050 |
| Cr | ≤0.25 | — |
Properties compared
| Property | 40Mn | 1040 |
|---|---|---|
| Density | 7.85 g/cm³ | 7.85 g/cm³ |
| Note | Quench-and-temper response above plain grade 40 thanks to 0.70–1.00% Mn | — |
| Tensile strength | — | 570–660 MPa (normalized, typ.) |
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: 40Mn · 1040. Substitution decisions for certified parts stay with the design authority.