Y15 vs Y12
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.
Y15
Carbon Steel
Y15 is the higher-carbon companion of Y12 in China’s sulfur-phosphorus free-cutting family (GB/T 8731): the same low-silicon, high-sulfur, high-phosphorus concept with carbon raised to 0.10–0.18% and manganese to 0.80–1.20% for somewhat better strength.
Standards: AISI 1215 (near) · JIS SUM family (near) · GB Y15 (GB/T 8731)
Y12
Carbon Steel
Y12 is China’s standard sulfur-phosphorus free-cutting steel (GB/T 8731), the domestic equivalent of the 1215 concept. It is produced in large volumes for automatic-lathe parts across Chinese machining shops.
Standards: AISI 1215 (near) · JIS SUM family (near) · GB Y12 (GB/T 8731)
Chemical composition compared (%)
| Element | Y15 | Y12 |
|---|---|---|
| C | 0.10–0.18 | 0.08–0.16 |
| Si | ≤0.15 | ≤0.15 |
| Mn | 0.80–1.20 | 0.70–1.00 |
| P | 0.08–0.15 | 0.08–0.15 |
| S | 0.23–0.33 | 0.23–0.33 |
Properties compared
| Property | Y15 | Y12 |
|---|---|---|
| Tensile strength | 410–530 MPa (hot rolled, typ.) | 380–460 MPa (hot rolled, typ.) |
| Density | 7.85 g/cm³ | 7.85 g/cm³ |
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: Y15 · Y12. Substitution decisions for certified parts stay with the design authority.