Y30
Data verifiedY30 is the 0.30% carbon member of the GB/T 8731 free-cutting family: sulfur (0.15–0.25%) keeps it fast on the lathe while the medium-carbon base allows real heat treatment, bridging free-cutting bar and plain machinery steel.
Chemical composition
| Element | Content (%) |
|---|---|
| C | 0.27–0.34 |
| Si | 0.15–0.35 |
| Mn | 0.70–1.00 |
| P | ≤0.06 |
| S | 0.15–0.25 |
Weight percent, per the governing standard ranges. Actual values per heat are on the mill certificate.
Properties
| Tensile strength | 490–610 MPa (hot rolled, typ.) |
| Density | 7.85 g/cm³ |
Heat treatment
Can be quenched and tempered or induction hardened for higher working strength than the low-carbon Y grades.
Equivalent grades
| Standard | Designation |
|---|---|
| gb | Y30 (GB/T 8731) |
Compare side by side: Y30 vs Y20 · Y30 vs Y40Mn
Equivalents overlap in chemistry and use but are not always identical — see our equivalents guide before substituting in certified designs.
Applications & Processing
Applications: Turned and heat-treated shafts, bolts, pins and fittings needing both machining speed and working strength.
Processing: Machinability good for its strength level; harden after rough machining; weldability poor due to sulfur.
Need Y30 from stock?
Steel.Wiki is sponsored by Shenzhen NewAsia Special Steel (Nasteel), a special-steel stockholder in Shenzhen stocking mold, tool and alloy steels with EN 10204 3.1 certification.
Ask for a quotationVisit NasteelSource: GB/T 8731 published ranges · Last updated 2026-11-03. Data is indicative — verify critical values against the governing standard and mill certificate before use.