AH40
Data verifiedAH40 is the 390 MPa higher-tensile hull steel of the classification-society system (ASTM A131 / GB/T 712 family). It steps above AH36 where scantlings get thin — large container ships and VLCCs use AH40/DH40/EH40 to cut hull weight while keeping 0 °C-class toughness for the A grade.
Chemical composition
| Element | Content (%) |
|---|---|
| C | ≤0.18 |
| Si | ≤0.50 |
| Mn | 0.90–1.60 |
| P | ≤0.035 |
| S | ≤0.035 |
| Note | Nb/V/Ti grain-refining per class rules |
Weight percent, per the governing standard ranges. Actual values per heat are on the mill certificate.
Properties
| Yield strength | ≥390 MPa |
| Tensile strength | 510–660 MPa |
| Impact | 0 °C, ≥41 J longitudinal (≤50 mm) |
| Density | 7.85 g/cm³ |
Heat treatment
Supplied normalized or TMCP under class survey; TMCP is standard for modern AH40 orders.
Equivalent grades
| Standard | Designation |
|---|---|
| aisi | A131 AH40 |
| jis | KA40 (near) |
| gb | AH40 (GB/T 712) |
Compare side by side: AH40 vs AH36 · AH40 vs DH40 · AH40 vs EH40
Equivalents overlap in chemistry and use but are not always identical — see our equivalents guide before substituting in certified designs.
Applications & Processing
Applications: Hull shells and decks of large vessels, hatch covers, offshore structures, ice-going tonnage (with the right toughness letter).
Processing: Certified plate-by-plate by the class society; order with the survey and mill certificates the yard’s class requires.
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Ask for a quotationVisit NasteelSource: ASTM A131 / class rules published ranges · Last updated 2026-11-03. Data is indicative — verify critical values against the governing standard and mill certificate before use.