A302 Gr.B
Data verifiedASTM A302 Grade B is a manganese-molybdenum-nickel vessel plate: the Mn-Mo base of A204 with a nickel addition for toughness and hardenability in thicker sections. It has a long history in boiler drums and nuclear-adjacent pressure equipment.
Chemical composition
| Element | Content (%) |
|---|---|
| C | ≤0.20 (≤25 mm) |
| Si | 0.15–0.40 |
| Mn | 1.15–1.50 |
| P | ≤0.025 |
| S | ≤0.025 |
| Mo | 0.45–0.60 |
| Ni | 0.40–0.70 |
Weight percent, per the governing standard ranges. Actual values per heat are on the mill certificate.
Properties
| Yield strength | ≥345 MPa |
| Tensile strength | 550–690 MPa |
| Density | 7.85 g/cm³ |
Heat treatment
Supplied normalized or normalized and tempered; heavy sections are quench-and-temper territory (see A302 Gr.C/D variants for Q&T supply).
Equivalent grades
| Standard | Designation |
|---|---|
| aisi | A302 Gr.B |
Compare side by side: A302 Gr.B vs A204 Gr.B · A302 Gr.B vs A537 Cl.1
Equivalents overlap in chemistry and use but are not always identical — see our equivalents guide before substituting in certified designs.
Applications & Processing
Applications: Boiler drums, heavy-wall pressure vessels, steam generators, thick-section process equipment.
Processing: Weld with low-hydrogen Mn-Mo-Ni consumables; preheat and PWHT per thickness — the chemistry is air-hardening enough that code welding procedure qualification matters.
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Ask for a quotationVisit NasteelSource: ASTM A302 published ranges · Last updated 2026-11-03. Data is indicative — verify critical values against the governing standard and mill certificate before use.