Section 2 Normal strength steels for ship and other structural applications

2.1.1 The requirements of this Section are primarily intended to apply to steel plates and wide flats not exceeding 100 mm in thickness and sections and bars not exceeding 50 mm in thickness in Grades A, B, D and E. For greater thicknesses, variations in the requirements may be permitted or required for particular applications.

2.1.2 Additional approval tests may be required to verify the suitability for forming and welding of Grade E plate exceeding 50 mm in thickness.

2.2.1 The method of deoxidation and the chemical composition of ladle samples are to comply with the requirements given in Table 3.2.1 Chemical composition and deoxidation practice.

2.2.2 Small variations from the chemical compositions given in Table 3.2.1 Chemical composition and deoxidation practice may be allowed for Grade E steel in thicknesses exceeding 50 mm or when any Grade of steel is supplied in a thermo-mechanically controlled processed condition, provided that these variations are documented and approved in advance.

2.2.3 The manufacturer's declared analysis will be accepted subject to occasional checks if required by the Surveyors.

2.2.4 For plate supplied from coil, the chemical analysis can be transposed from the certificate of the coil manufacture onto the re-processor's certificate.

2.3.1 All materials are to be supplied in a condition complying with the requirements given in Table 3.2.2 Condition of supply. Where alternative conditions are permitted these are at the option of the steelmaker, unless otherwise expressly stated in the order for the material, but a steelmaker is to supply materials only in those conditions for which he has been approved by LR.

2.3.2 Where normalising rolling and thermomechanically controlled rolling (T.M.) processes are used, it is the manufacturer's responsibility to ensure that the programmed rolling schedules are adhered to. Where deviation from the programmed rolling schedule occurs, the manufacturer must ensure that each affected piece is tested and that the local Surveyor is informed.

2.3.3 If a steel product supplied in the T.M. condition is to be subjected to heating for forming or stress relieving or is to be welded by a high energy input process, consideration must be given to the possibility of a consequent reduction in mechanical properties.

2.4.1 The results of all tensile tests and the average energy value from each set of three impact tests are to comply with the appropriate requirements given in Table 3.2.3 Mechanical properties for acceptance purposes except where enhanced by the requirements of this Section.

2.4.2 With the exception given in Ch 3, 2.4 Mechanical tests 2.4.4, one tensile test is to be made for each batch presented unless the mass of finished material is greater than 50 tonnes, in which case one test is to be made from a different piece from each 50 tonnes or fraction thereof. Additional tests are to be made for every variation of 10 mm in the thickness or diameter of products from the same cast. For sections, the thickness to be considered is the thickness of the product at the point at which samples are taken for mechanical tests. A piece is to be regarded as the rolled product from a single slab or billet, or from a single ingot if this is rolled directly into plates, strip, sections or bars.

2.4.3 For Grades A and B where plate is supplied from coil, results of the tensile test can be transposed from the certificate of the coil manufacture onto the certificate issued by the re-processor. If the coil mass exceeds 50 tonnes, testing will additionally be required from two locations representing the start and end of the coil. For Grades D and E, the mechanical properties must be sampled from the decoiled plate in accordance with the frequency specified in the Rules.

2.4.4 For plates of thickness exceeding 50 mm in Grade E steel, one tensile test is to be made on each piece.

Table 3.2.3 Mechanical properties for acceptance purposes

Grade	Yield stress N/mm2minimum	Tensile strength N/mm2			Elongation on 5,65 % minimum		Charpy V-notch impact test (see Notes 3, 4, 5, 6)
							Thickness mm			Average energy J minimum
										Longitudinal	Transverse
A, B, D, E	235	400 - 520 (see Note 1)			22 (see Note 2)		≤50 >50≤70 >70≤100			27 34 41	20 24 27
Impact tests are to be made on the various grades at the following temperatures:							A grade B grade D grade E grade			not required 0°C -20°C -40°C
Note 1. For sections in Grade A, the upper limit of the tensile strength range may be exceeded at the discretion of the Surveyor.
Note 2. For full thickness tensile test specimens with a width of 25 mm and a gauge length of 200 mm (see Figure 2.2.4 Test specimen dimensions for plates, strip and sections - II), the minimum elongation is to be:
	Thickness mm		>5	>10	>15	>20	>25	>30	>35
		≤5	≤10	≤15	≤20	≤25	≤30	≤35	≤50
	Elongation %	14	16	17	18	19	20	21	22
Note 3. See Ch 3, 2.4 Mechanical tests 2.4.5 and Ch 3, 2.4 Mechanical tests 2.4.6. Note 4. See Ch 3, 2.4 Mechanical tests 2.4.7. Note 5. See Ch 3, 1.9 Test material and mechanical tests 1.9.11.

2.4.5 For Grade A steel, Charpy V-notch impact tests are not required when the thickness does not exceed 50 mm, or up to 100 mm thick if the material is supplied in either the normalised or thermomechanically controlled-rolled condition and has been fine grain treated. However, the manufacturer should confirm, by way of regular in-house checks, that the material will meet a requirement of 27 J at +20 °C. The results of these checks shall be reported to the Surveyor. The frequency of these checks should as a minimum be every 250 tonnes.

2.4.6 When Grade A steel is supplied in a thickness greater than 50 mm and either, in the normalising rolled condition, or when special approval has been given to be supply in the as-rolled condition, a set of three impact test specimens is to be tested from each batch of 50 tonnes or fraction thereof.

2.4.7 Impact tests are not required for Grade B steel of 25 mm or less in thickness. However, the manufacturer is to confirm, by way of regular in-house tests, and on occasional material selected by the Surveyor, that the material meets the requirement in Table 3.2.3 Mechanical properties for acceptance purposes. The results of the tests are to be reported to the Surveyor. The frequency of the in-house checks are to be, as a minimum, one set of three impact test specimens for every 250 tonnes.

2.4.8 For Grade B steels of thicknesses above 25 mm, supplied in the as-rolled or normalising rolled condition, one set of three impact test specimens is to be made from the thickest item in each batch presented. If the mass of finished material is greater than 25 tonnes, one extra set of tests is to be made from a different piece from each 25 tonnes or fraction thereof.

2.4.9 For Grade B steels of thicknesses above 25 mm, supplied in the furnace normalised or thermomechanically controlled-rolled condition, one set of three impact test specimens is to be made from the thickest item in each batch presented. If the mass of finished material is greater than 50 tonnes, one extra set of tests is to be made from a different piece from each 50 tonnes or fraction thereof.

2.4.10 For Grade D steels supplied in the as-rolled or normalising rolled condition, one set of three impact test specimens is to be made from the thickest item in each batch presented. If the mass of finished material is greater than 25 tonnes, one extra set of tests is to be made from a different piece from each 25 tonnes or fraction thereof.

2.4.11 For Grade D steels, supplied in the furnace normalised or thermomechanically controlled-rolled condition, one set of three impact test specimens is to be made from the thickest item in each batch presented. If the mass of finished material is greater than 50 tonnes, one extra set of tests is to be made from a different piece from each 50 tonnes or fraction thereof.

2.4.12 For plates in Grade E steel, one set of three impact test specimens is to be made from each piece. For bars and sections in Grade E steel, one set of three test specimens is to be made from each 25 tonnes or fraction thereof. When, subject to the special approval of LR, sections are supplied in the as-rolled or normalising rolled conditions, one set of impact tests is to be taken from each batch of 15 tonnes or fraction thereof.

2.4.13 The results of all tensile tests and the average energy values from each set of three impact tests are to comply with the appropriate requirements given in Table 3.2.3 Mechanical properties for acceptance purposes. For impact tests, one individual value may be less than the required average value provided that it is not less than 70 per cent of this average value. See Ch 1, 4.6 Re-test procedures for re-test procedures.

2.4.14 Where standard subsidiary Charpy V-notch test specimens are necessary, see Ch 2, 3.2 Testing procedures 3.2.4.

2.5.1 The particulars detailed in Ch 3, 1.12 Identification of materials are to be marked on all materials which have been accepted. Where a number of light materials are bundled, the bundle is to be identified in accordance with Ch 3, 1.12 Identification of materials 1.12.2.

2.6.1 At least two copies of each test certificate are to be provided. They are to be of the type and give the information detailed in Ch 3, 1.13 Certification of materials and, additionally, are to indicate if sections in Grade A steel of rimming quality have been supplied. As a minimum, the chemical composition is to include the contents of any grain refining elements used and the residual elements, as detailed in Table 3.2.1 Chemical composition and deoxidation practice.