Q390B
Data verifiedQ390B is the 390 MPa step in the GB/T 1591 HSLA ladder, microalloyed with Nb/V/Ti for strength without a carbon increase. It fills the gap between Q355 and Q420 in Chinese machinery and construction design.
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 | ≥390 MPa (≤16 mm) |
| Tensile strength | 490–650 MPa |
| Impact | B grade: 34 J at 20 °C |
| Density | 7.85 g/cm³ |
Heat treatment
Supplied hot rolled, normalized or TMCP.
Equivalent grades
| Standard | Designation |
|---|---|
| aisi | A572 Gr.60 (near) |
| jis | SM570 (near) |
| gb | Q390B (GB/T 1591) |
Equivalents overlap in chemistry and use but are not always identical — see our equivalents guide before substituting in certified designs.
Applications & Processing
Applications: Cranes, excavators, high-rise columns, heavy welded structures.
Processing: Weldable with standard HSLA practice; low carbon keeps preheat modest for normal thicknesses.
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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.