Q420B
Data verifiedQ420B is a 420 MPa yield HSLA steel to GB/T 1591, widely used in Chinese crane, mining and power-transmission construction. Microalloying plus controlled rolling delivers the strength with a weldable, low-carbon analysis.
Chemical composition
| Element | Content (%) |
|---|---|
| C | ≤0.20 |
| Si | ≤0.50 |
| Mn | ≤1.70 |
| P | ≤0.035 |
| S | ≤0.035 |
| Nb | 0.015–0.06 |
| V | 0.02–0.15 |
Weight percent, per the governing standard ranges. Actual values per heat are on the mill certificate.
Properties
| Yield strength | ≥420 MPa (≤16 mm) |
| Tensile strength | 520–680 MPa |
| Impact | B grade: 34 J at 20 °C |
| Density | 7.85 g/cm³ |
Heat treatment
Supplied normalized or TMCP for best toughness.
Equivalent grades
| Standard | Designation |
|---|---|
| din | S420 class (near) |
| aisi | A572 Gr.60/65 (near) |
| gb | Q420B (GB/T 1591) |
Compare side by side: Q420B vs Q390B · Q420B vs Q460C
Equivalents overlap in chemistry and use but are not always identical — see our equivalents guide before substituting in certified designs.
Applications & Processing
Applications: Crane girders, transmission towers, mining machinery, large welded frames.
Processing: Good weldability; for thick joints follow the mill’s preheat recommendations for the C quality and above.
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Ask for a quotationVisit NasteelSource: GB/T 1591 published ranges · Last updated 2026-11-03. Data is indicative — verify critical values against the governing standard and mill certificate before use.