| Article 2 | Normal and higher strength steels for hull and other structural applications |
| 2.1 | Scope |
2.1.1
The requirements of this Article apply to weldable normal and higher strength steel hot rolled plates, wide flats, sections and bars intended for use in hull construction and other structural applications.
2.1.2
Provision is made for:
- plates and wide flats of all grades not exceeding 100 mm in thickness
- sections and bars of all grades not exceeding 50 mm in thickness.
For thickness greater than the above, the requirements may be modified, as appropriate, in the individual cases.
| 2.2 | Steel grades |
2.2.1
The steels are classed, on the basis of a minimum yield strength level ReH (N/mm2), into normal strength (ReH=235) and higher strength (32: ReH=315 - 36: ReH=355 - 40: ReH = 390).
Normal strength steels are divided into four grades A, B, D and E. For normal strength steels, the letters A, B, D and E mean impact properties at +20, 0, -20 and -40˚C, respectively.
Higher strength steels are divided into four grades identified by the letters AH, DH, EH and FH followed by a number related to the yield strength level. For higher strength steels, the letters AH, DH, EH and FH mean impact properties at 0, -20, -40 and -60˚C, respectively.
2.2.2Steels differing in chemical composition, deoxidation practice, conditions of supply and mechanical properties may be accepted, subject to the special approval of the Society. Such steels are to be given a special designation.
| 2.3 | Manufacture |
The Manufacturers are to be approved by the Society and the relevant requirements of [1.2] apply.
The method of deoxidation is specified in Tab 1 and Tab 2.
| Table 1 - Normal strength steels - Chemical composition and deoxidation practice |
| Steel grade | A | B | D | E |
|---|---|---|---|---|
| ( 1 ) For sections up to a thickness of 12,5 mm, rimmed steel may be accepted subject to the special approval of the Society. ( 2 ) When any grade of steel is supplied in the thermo-mechanically rolled condition, variations in the specified chemical composition may be allowed or required by the Society and are to be stated at the approval. ( 3 ) The Society may limit the amount of residual elements which may have an adverse effect on the working and use of the steel, e.g. copper and tin. ( 4 ) Where additions of any other element have been made as part of the steelmaking practice, the content is to be indicated in the ladle analysis certificate. ( 5 ) C +1/6 Mn is not to exceed 0,40%. ( 6 ) Max. 0,23% for sections. ( 7 ) When Grade B steel is impact tested, the minimum manganese content may be reduced to 0,60%. ( 8 ) Al is required for thickness greater than 25 mm. ( 9 ) The total aluminum content may be determined instead of acid soluble content. In such cases the total aluminum content is to be not less than 0,020%. Other suitable grain refining elements may be used subject to the special approval of the Society. | ||||
| Deoxidation practice for thickness t (mm) | t ≤ 50 mm: any method except rimmed (1) t > 50 mm: killed | t ≤ 50 mm: any method except rimmed t > 50 mm: killed | t ≤ 25 mm: killed t > 25 mm: killed and fine grain treated | killed and fine grain treated |
| Chemical composition | ||||
| C max (5) Mn min (5) Si max P max S max Al (acid soluble) min | 0,21 (6) 2,5 x C 0,50 0,035 0,035 | 0,21 0,80 (7) 0,35 0,035 0,035 | 0,21 0,60 0,35 0,035 0,035 | 0,18 0,70 0,35 0,035 0,035 0,015 (9) |
Dear AllCan anybody give info about LR A grade materialThanks & Regards.Manoj--
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