Section 1 Plates, bars and sections

1.1.1 This Section makes provision for aluminium alloy plates, bars and sections intended for use in the construction of ships and other marine structures and for cryogenic applications.

1.1.2 Except as provided in Ch 8, 1.1 Scope 1.1.4, all items are to be manufactured and tested in accordance with the appropriate requirements of Ch 1 General Requirements and Ch 2 Testing Procedures for Metallic Materials and those detailed in this Section.

1.1.3 The thickness of plates, sections and bars described by these requirements will be in the range between 3 and 50 mm. Plates and sections less than 3,0 mm thick may be manufactured and tested in accordance with the requirements of an acceptable national specification.

1.1.4 Plates less than 3,0 mm thick and sections less than 40 mm × 40 mm × 3,0 mm may be manufactured and tested in accordance with the requirements of an acceptable National specification.

1.1.5 Where the section thickness exceeds 50 mm the requirements will be subject to special consideration.

1.1.6 Materials intended for the construction of cargo tanks or storage for liquefied gases, and for other low temperature applications, are to be manufactured in the 5083 alloy in the annealed condition.

1.1.7 As an alternative to Ch 8, 1.1 Scope 1.1.2 and Ch 8, 1.1 Scope 1.1.4, materials which comply with National or proprietary specifications may be accepted provided that these specifications give reasonable equivalence to the requirements of this Section and are approved for a specific application. Generally, survey and certification are to be carried out in accordance with the requirements of Ch 1 General Requirements.

1.2.1 Aluminium alloys are to be manufactured at works approved by Clasifications Register (hereinafter referred as 'LR').

1.2.2 The alloys may be cast either in ingot moulds or by an approved continuous casting process. Plates are to be formed by rolling and may be hot or cold finished. Bars and sections may be formed by extrusion, rolling or drawing.

1.2.3 All melts are to be suitably degassed prior to casting such that the aim hydrogen content is less than 0,2 ml per 100 g.

1.3.1 Materials are to be free from surface or internal defects of such a nature as would be harmful in service.

1.3.2 The manufacturer is to verify the integrity of pressure welds of closed extrusion profiles in accordance with Ch 8, 1.10 Pressure weld tests.

1.4.1 Underthickness tolerances for rolled products for marine construction are given in Table 8.1.1 Underthickness tolerances for rolled products for marine construction.

1.4.2 Underthickness tolerances for extruded products are to comply with an acceptable National or International Standard.

1.4.3 There are to be no underthickness tolerances for materials for application in cryogenic process pressure vessels.

1.4.4 Dimensional tolerances other than permitted underthicknesses are to comply with an acceptable National or International Standard.

1.4.5 Verification of dimensions is the responsibility of the manufacturer. Acceptance by Surveyors of material which is later found to be defective does not absolve the manufacturer from this responsibility.

1.5.1 Samples for chemical analysis are to be taken representative of each cast, or the equivalent where a continuous melting process is involved.

1.5.2 The chemical composition of these samples is to comply with the requirements of Table 8.1.2 Chemical composition, percentage.

Table 8.1.3 Minimum mechanical properties for acceptance purposes of selected rolled aluminium alloy products

Alloy and temper condition, see Note 3	Thickness, t, mm	0,2% proof stress R p, N/mm2	Tensile strength R m N/mm2	Elongation 4d, %	Elongation on 5d,%
5083-O	3 ≤ t ≤ 50 (see Note 2)	125	275–350	16	14
5083-H111	3 ≤ t ≤ 50	125	275-350	16	14
5083-H112	3 ≤ t ≤ 50	125	275	12	10
5083-H116	3 ≤ t ≤ 50	215	305	10	10
5083-H321	3 ≤ t ≤ 50	215–295	305–380	12	10
5086-O	3 ≤ t ≤ 50	100	240–305	16	14
5086-H111	3 ≤ t ≤ 50	100	240–305	16	14
5086-H112	3 ≤ t ≤12,5	125	250	8	–
	12,5 < t ≤ 50	105	240	–	9
5086-H116	3 ≤ t ≤ 50	195	275	10 (see Note 1)	9
5059-O	3 ≤ t ≤ 50	160	330	24	24
5059-H111	3 ≤ t ≤ 50	160	330	24	24
5059-H116	3 ≤ t ≤ 20	270	370	10	10
	20 < t ≤ 50	260	360	10	10
5059-H321	3 ≤ t ≤ 20	270	370	10	10
	20 < t ≤ 50	260	360	10	10
5383-O	3 ≤ t ≤ 50	145	290	17	17
5383-H111	3 ≤ t ≤ 50	145	290	17	17
5754-H111	3 ≤ t ≤ 50	80	190–240	18	17
5383-H116	3 ≤ t ≤ 50	220	305	10	10
5383-H321	3 ≤ t ≤ 50	220	305	10	10
5456-O	3 ≤ t ≤ 6,3	130–205	290–365	16	–
	6,3 ≤ t ≤ 50	125–205	285–360	16	14
	3 ≤ t ≤ 30	230	315	10	10
5456-H116	30 < t ≤ 40	215	305	–	10
	40 < t ≤ 50	200	285	–	10
	3 ≤ t ≤ 12,5	230–315	315–405	12	–
5456-H321	12,5 ≤ t ≤ 40	215–305	305–385	–	10
	40 ≤ t ≤ 50	200–295	285–370	–	10
5754-O	3 ≤ t ≤ 50	80	190–240	18	17
Note 1. 8% for thickness up to and including 6,3 mm.
Note 2. For application to liquefied natural gas carriers or liquefied natural gas tankers where thicknesses are in excess of 50 mm, the mechanical properties given in this table are, in general, to be complied with.
Note 3. The mechanical properties for the O and H111 tempers are the same for all alloys shown in this Table. However, they are separated in this Table as they are made using different manufacturing processes

1.6.1 The Aluminium 5000 series alloys, capable of being strain hardened, are to be supplied in any of the following temper conditions:

1.6.2 The H116 temper is specially developed for use in a marine environment.

1.6.3 The Aluminium 6000 series alloys, capable of being age hardened, are to be supplied in either of the following temper conditions:

1.7.1 Plate with the same thickness and from a single cast or equivalent, are to be presented for test in batches of not more than 2 tonnes, with the exceptions of those given in Ch 8, 1.7 Test material 1.7.2 and Ch 8, 1.7 Test material 1.7.3.

1.7.2 For single plates or coils weighing more than 2 tonnes, only one tensile specimen per plate or coil is to be taken.

1.7.3 A tensile test specimen is required from each plate to be used in the construction of cargo tanks, secondary barriers and process pressure vessels with design temperatures below -55°C.

1.7.4 Bars and sections of less than 1 kg/m in nominal weight are to be tested in batches of 1 tonne. Bars and sections with a nominal weight between 1 kg/m and 5 kg/m are to be tested in batches of 2 tonnes. Where the nominal weight is greater than 5 kg/m, one tensile test is to be carried out for every 3 tonnes produced, or fractions thereof.

1.7.5 If the material is supplied in the heat treated condition, each batch is to be treated together in the same furnace or subjected to the same finishing treatment when a continuous furnace is used.

1.7.6 For plates over 300 mm in width, tensile test specimens are to be cut with their length transverse to the principal direction of rolling. For narrow plates and for sections and bars, the test specimens are to be cut in the longitudinal direction. Longitudinal tensile test specimens are accepted for the strain hardenable 5000 series alloys.

1.7.7 Longitudinal tensile test specimens from a plate are to be taken at width from the longitudinal edge. Longitudinal tensile test specimens taken from extruded sections should be taken in the range from to of the distance from the edge to the centre of the thickest region of the section.

1.8.1 At least one tensile test specimen is to be prepared from each batch of material submitted for acceptance.

1.8.2 Tensile test specimens are to be machined to the dimensions given in Figure 2.2.3 Test specimen dimensions for plates, strip and sections - I and aluminum alloys in Chapter 2. Alternatively, machined proportional test specimens of circular cross-section in accordance with Figure 2.2.2 Test specimen dimensions for forgings and castings - II and aluminum alloys in Chapter 2 may be used provided that the diameter is not less than 10 mm. Round bars may be tested in full section, or test specimens may be machined in accordance with the dimensions given in Figure 2.2.2 Test specimen dimensions for forgings and castings - II and aluminum alloys in Chapter 2.

1.8.3 The results of all tensile tests are to comply with the values given in Table 8.1.3 Minimum mechanical properties for acceptance purposes of selected rolled aluminium alloy products and Table 8.1.4 Minimum mechanical properties for acceptance purposes of selected extruded aluminium alloy products, as applicable.

Table 8.1.4 Minimum mechanical properties for acceptance purposes of selected extruded aluminium alloy products

Alloy and temper condition, See Note 2	Thickness, t, mm	0,2% proof stress R p, N/mm2	Tensile strength R m N/mm2	Elongation on 4d, %	Elongation on 5d, %
5083-O	3 ≤ t ≤ 50	110	270–350	14	12
5083-H111	3 ≤ t ≤ 50	165	275	12	10
5083-H112	3 ≤ t ≤ 50	110	270	12	10
5086-O	3 ≤ t ≤ 50	95	240–315	14	12
5086-H111	3 ≤ t ≤ 50	145	250	12	10
5086-H112	3 ≤ t ≤ 50	95	240	12	10
5059-H112	3 ≤ t ≤ 50	200	330	10	10
5383-O	3 ≤ t ≤ 50	145	290	17	17
5383-H111	3 ≤ t ≤ 50	145	290	17	17
5383-H112	3 ≤ t ≤ 50	190	310	13	13
6005A-T5	3 ≤ t ≤ 50	215	260	9	8
6005A-T6	3 ≤ t ≤ 10	215	260	8	6
	10 < t ≤ 50	200	250	8	6
6061-T6	3 ≤ t ≤ 50	240	260	10	8
6082-T5	3 ≤ t ≤ 50	230	270	8	6
6082-T6	3 ≤ t ≤ 5	250	290	6	–
	5 < t ≤ 50	260	310	10	8
Note 1. The values are applicable for longitudinal and transverse tensile test specimens as well. Note 2. The mechanical properties for the O and H111 tempers are the same for all alloys shown in this Table. However, they are separated in this Table as they are made using different manufacturing processes.

1.9.1 Rolled 5000 series alloys of type 5083, 5383, 5059, 5456 and 5086 in the H116 and H321 tempers intended for use in marine hull construction or in marine applications with frequent direct contact with seawater are to be corrosion tested with respect to exfoliation and intergranular corrosion resistance.

1.9.2 The manufacturer is to establish the relationship between microstructure and resistance to corrosion when the above alloys are approved. A reference photomicrograph taken at 500x, under the conditions specified in ASTM B928 Section 9.4.1, is to be prepared for each of the alloy-tempers and thickness ranges relevant. The reference photographs are to be taken from samples which have exhibited no evidence of exfoliation corrosion and a pitting rating of PB or better, when subjected to the test described in ASTM G66 (ASSET).The samples are also to have exhibited resistance to intergranular corrosion at a mass loss no greater than 15 mg/cm², when subjected to the test described in ASTM G67 (NAMLT). Upon satisfactory establishment of the relationship between microstructure and resistance to corrosion, the master photomicrographs and the results of the corrosion tests are to be approved by LR. Production practices are not to be changed after approval of the reference micrographs.

1.9.3 For batch acceptance of 5000 series alloys in the H116 and H321 tempers, metallographic examination of one sample selected from mid width at one end of a coil or random sheet or plate is to be carried out. The microstructure of the sample is to be compared to the reference photomicrograph of acceptable material in the presence of the Surveyor. A longitudinal section perpendicular to the rolled surface is to be prepared for metallographic examination, under the conditions specified in ASTM B928 Section 9.6.1. If the microstructure shows evidence of continuous grain boundary network of aluminium-magnesium precipitate in excess of the reference photomicrographs of acceptable material, the batch is either to be rejected or tested for exfoliation corrosion resistance and intergranular corrosion resistance subject to the agreement of the Surveyor. The corrosion tests are to be in accordance with ASTM G66 and G67 or equivalent standards. Acceptance criteria are that the sample shall exhibit no evidence of exfoliation corrosion and a pitting rating of PB or better when test subjected to ASTM G66 (ASSET) test, and the sample is to exhibit resistance to intergranular corrosion at a mass loss no greater than 15 mg/cm² when subjected to ASTM G67 (NAMLT) test. If the results from testing satisfy the acceptance criteria stated in Ch 8, 1.9 Corrosion tests 1.9.2, the batch is accepted, otherwise it is to be rejected.

1.9.4 As an alternative to metallographic examination, each batch may be tested for exfoliation corrosion resistance and intergranular corrosion resistance, in accordance with ASTM G66 and G67 under the conditions specified in ASTM B298, or equivalent standards. If this alternative is used, then the results of the test must satisfy the acceptance criteria stated in Ch 8, 1.9 Corrosion tests 1.9.2.

1.9.5 Tempers that are corrosion tested in accordance with Ch 8, 1.9 Corrosion tests 1.9.3 are to be marked 'M' after the temper condition, e.g. 5083 H321 M.

1.10.1 The integrity of pressure welds of closed profile extrusions is to be verified by examination of macrosections or drift expansion tests.

1.10.2 Every closed profile extrusion is to be sampled, except where the closed profile extrusions are equal to or shorter than 6,0 m long, in which case a batch is to comprise of five profiles. Every sample is to be tested at both ends after final heat treatment.

1.10.3 Where verification is by examination of macrosections, no indication of lack of fusion is permitted.

1.10.4 Where verification of fusion at pressure welds of closed profile extrusions is by drift expansion test, testing is to be generally in accordance with Ch 2, 4.3 Drift expanding tests. The minimum included angle of the mandrel is to be 60°, and the minimum specimen length, 50 mm. For acceptance, there is to be no failure by a clean split along the weld line.

1.11.1 Surface inspection and verification of dimensions are the responsibility of the manufacturer, and acceptance by the Surveyors of material later found to be defective shall not absolve the manufacturer from this responsibility.

1.11.2 In general, the non-destructive examination of materials is not required for acceptance purposes. Manufacturers are expected, however, to employ suitable methods of non-destructive examination for the general maintenance of quality standards.

1.11.3 For applications where the non-destructive examination of materials is considered to be necessary, the extent of this examination, together with appropriate acceptance standards, are to be agreed between the purchaser, manufacturer and Surveyor. Advanced NDE methods, as described in Ch 1, 5.11 Advanced NDE methods, may be applied in lieu of or complementary to existing NDE methods, as appropriate to the material type, thickness, complexity and geometry.

1.12.1 Slight surface imperfections may be removed by mechanical means, provided that the prior agreement of the Surveyor is obtained, that the work is carried out to his satisfaction and that the final dimensions are acceptable. The repair of defects by welding is not allowed.

1.13.1 The manufacturer is to adopt a system of identification which will ensure that all finished material in a batch presented for test is of the same nominal chemical composition.

1.13.2 Products are to be clearly marked by the manufacturer in accordance with the requirements of Ch 1 General Requirements. The following details are to be shown on all materials which have been accepted:

1. Manufacturer's name or trade mark.

2. Alloy grade and temper condition.

3. Identification mark which will enable the full history of the item to be traced.

4. The stamp of the LR brand.

1.13.3 Where a number of light products weighting ≤ 50 kg per meter, are securely fastened together in bundles, the manufacturer may brand only each bundle. A firmly fastened durable label containing the identification may be attached to each bundle.

1.14.1 A manufacturer’s certificate validated by LR is to be issued, see Ch 1, 3.1 General.

1.14.2 Each test certificate is to include the following particulars:

1. Purchaser's name and order number.

2. Contract number.

3. Address to which material is to be despatched.

4. Description and dimensions.

5. Alloy grade and temper condition.

6. Identification mark which will enable the full history of the item to be traced.

7. Chemical composition.

8. Mechanical test results (not required on shipping statement).

9. Details of temper condition and heat treatment, where applicable.

10. Corrosion test results (as applicable).

1.14.3 Where the alloy is not produced at the works at which it is wrought, a certificate is to be supplied by the manufacturer of the alloy stating the cast number and chemical composition. The works at which the alloy was produced must be approved by LR.