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Sec.5: Aluminium Alloys [Table of Contents] Sec.6: Testing Procedures

DNV-OS-B101 Metallic Materials

[-] Ch.2: Technical Provisions
[-] Sec.5: Aluminium Alloys
[-] A: Wrought Aluminium Alloys

Ch.2 Sec.5
A. Wrought Aluminium Alloys

Ch.2 Sec.5
A 100   Scope

Ch.2 Sec.5 A
101   This subsection specifies the requirements for aluminium alloy plates, sections, tubes and bars to be used in the construction of hulls and other marine structures and for cryogenic applications. These requirements are applicable to wrought aluminium products within the thickness range of 3 mm to 50 mm.

Ch.2 Sec.5 A
102   Where required by the relevant design and construction parts of the DNV Offshore Standards, wrought aluminium alloys shall comply with the requirements of Ch.1 Sec.1 and Sec.6 and the requirements of this subsection.

Ch.2 Sec.5 A
103   As an alternative to 102, materials which comply with national or proprietary specifications may be accepted provided such specifications give reasonable equivalence to the requirements of this section or are approved for each specific application. Generally, such materials shall comply with the appropriate requirements of Ch.1 Sec.1 and Sec.6.

Ch.2 Sec.5
A 200   Aluminium grades and temper conditions

Ch.2 Sec.5 A
201   The alloy grades are listed in Table A1. The numerical designation (grade) of aluminium alloys are based on those of the Aluminium Association. Temper conditions (delivery heat treatment) are defined in EN 515 or ANSI H35.1.

Ch.2 Sec.5 A
202   5000 series alloys shall be supplied in any of the temper conditions given in Table A2 and Table A3, as applicable. 6000 series alloys shall be supplied in any of the temper conditions given in Table A3.

Ch.2 Sec.5 A
203   The use of 6000 series aluminium alloys in direct contact with sea water may be restricted depending on application and corrosion protection system. The use of these alloys shall be subject to agreement.

Ch.2 Sec.5 A
204   Unless otherwise approved, aluminium for cryogenic applications shall be of the 5000 series alloys and supplied in the annealed condition.

Ch.2 Sec.5
A 300   Manufacture

Ch.2 Sec.5 A
301   The alloys may be cast either in ingot moulds or by a continuous casting process. Plates shall be formed by rolling and may be hot or cold finished. Sections, bars and tubes may be formed by extrusion, rolling or drawing.

Ch.2 Sec.5 A
302   The materials shall have a finish consistent with the method of manufacture and shall be free from imperfections which, due to their nature, degree or extent, will interfere with the use of the materials.

Ch.2 Sec.5
A 400   Chemical composition

Ch.2 Sec.5 A
401   The chemical composition of each heat shall be determined by the manufacturer on a sample taken preferably during the pouring of the heat. The chemical composition shall comply with the limits given in Table A1.

Ch.2 Sec.5 A
402   Other alloys or alloys which do not fully comply with Table A1, may be accepted after consideration in each particular case. Special tests and/or other relevant information, e.g. which confirm satisfactory corrosion resistance and weldability, may be required.

Ch.2 Sec.5
A 500   Test material and test pieces for mechanical
testing

Ch.2 Sec.5 A
501   For rolled products, the test material shall be taken at one third of the width from a longitudinal edge. The test pieces are normally to be cut with their longitudinal axis transverse to the final rolling direction. If the width is insufficient to obtain transverse tests, longitudinal tests will be permitted.

Ch.2 Sec.5 A
502   For extruded products, the test material shall be taken in the range 1/3 to 1/2 of the distance from the edge to the centre of the thickest part of the section. The test pieces are normally to be cut with their longitudinal axes parallel to the extruding direction.

Ch.2 Sec.5 A
503   Flat tensile test piece of width 12.5 mm shall be used for thicknesses up to and including 12.5 mm. The test piece shall be prepared so that both rolled surfaces are maintained. Round tensile test piece shall be used for thicknesses over 12.5 mm. For thicknesses up to and including 40 mm, the longitudinal axis of the round tensile test piece shall be positioned at the mid-thickness. For thicknesses over 40 mm, the longitudinal axis shall be positioned at one quarter thickness below the surface.

Ch.2 Sec.5
A 600   Test units and number of tests

Ch.2 Sec.5 A
601   All materials in a test unit (lot) shall be of the same alloy grade, temper, heat, product form (plates, sections etc.) and thickness. Artificially aged grades are in addition to be from the same furnace charge.

Ch.2 Sec.5 A
602   For rolled products, one tensile test is required for each 2 000 kg, or fraction thereof, in each test unit. For single plates or for coils weighing more than 2 000 kg, only one tensile test per plate or coil is required.

Ch.2 Sec.5 A
603   For extruded products with a nominal mass of less than 1 kg/m, one tensile test is required for each 1 000 kg, or fraction thereof, in each test unit. For nominal masses between 1 and 5 kg/m, one tensile test is required for each 2 000 kg, or fraction thereof, in each test unit. Where the nominal mass exceeds 5 kg/m, one tensile test is required for each 3 000 kg, or fraction thereof, in each test unit.

Ch.2 Sec.5
A 700   Mechanical properties

Ch.2 Sec.5 A
701   The mechanical properties shall comply with the values given in Table A2 and Table A3, as applicable. Other temper conditions with related mechanical properties may be accepted by agreement.

Ch.2 Sec.5
A 800   Press weld testing

Ch.2 Sec.5 A
801   Proper fusion of press welds for closed profile extrusions shall be verified by macro section tests or drift expansion tests. Other tests may be accepted after consideration. Every fifth profile shall be sampled after final heat treatment. Test units of five profiles or less shall be sampled one profile. Profiles with lengths exceeding 6 m shall be sampled every profile in the start of the production. The number of tests may be reduced to every fifth profile if the results from the first three profiles are found acceptable. Every sample profile shall be tested at both ends.

Ch.2 Sec.5 A
802   Where verification is by macro section tests, no indication of lack of fusion at the press welds is permitted.

Ch.2 Sec.5 A
803   Where verification is by drift expansion test, the test pieces shall be cut with the ends perpendicular to the axis of the profile. The edges of the end may be rounded by filing. The minimum length of the test piece shall be twice the external diameter of the profile or 50 mm, whichever is greater. Testing shall be carried out at ambient temperature and shall consist of expanding the end of the profile by means of a conical mandrel having an included angle of at least 60°. The test is considered to be unacceptable if it fails with a clean split along the weld line.

Ch.2 Sec.5
A 900   Corrosion testing

Ch.2 Sec.5 A
901   Rolled 5000 series alloys of grade 5083, 5383, 5059, 5086 and 5456 in the H116 and H321 tempers intended for use in marine hull construction or in marine applications where frequent direct contact with seawater is expected shall be tested with respect to exfoliation and inter-granular corrosion resistance.

Ch.2 Sec.5 A
902   The manufacturers shall establish the relationship between microstructure and resistance to corrosion. A reference photomicrograph taken at 500 ´ shall be established for each of the alloy-tempers and thickness ranges relevant. The reference photographs shall 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 shall also have exhibited resistance to inter-granular corrosion at a mass loss no greater than 15 mg/cm2, when subjected to the test described in ASTM G67.

Ch.2 Sec.5 A
903   Upon satisfactory establishment of the relationship between microstructure and resistance to corrosion, the reference photomicrographs and the results of the corrosion tests shall be approved by the purchaser. Production practices shall not be changed after approval of the reference micrographs.

Ch.2 Sec.5 A
904   For test unit acceptance, metallographic examination of one sample selected from mid width at one end of a coil or random sheet or plate shall be carried out. A longitudinal section perpendicular to the rolled surface shall be prepared. The microstructure shall be compared to the reference photomicrograph of acceptable material. If the microstructure shows evidence of continuous grain boundary network of aluminium-magnesium precipitates in excess of the reference photomicrographs, the test unit shall either be rejected or tested for exfoliation-corrosion resistance and inter-granular corrosion resistance. The corrosion tests shall be in accordance with ASTM G66 and G67 or equivalent standards. If the results from testing satisfy the acceptance criteria stated in 902 the test unit is accepted, else it is rejected.

Ch.2 Sec.5 A
905   As an alternative to metallographic examination, each test unit may be tested for exfoliation-corrosion resistance and inter-granular corrosion resistance in accordance with ASTM G66 and G67 or equivalent standards.

Ch.2 Sec.5
A 1000   Inspection and tolerances

Ch.2 Sec.5 A
1001   Surface inspection and verification of dimensions are the responsibility of the manufacturer.

Ch.2 Sec.5 A
1002   Permissible under-thickness tolerances for rolled and extruded products are given in Table A4 and Table A5, respectively. Dimensional tolerances other than those given shall comply with a recognised standard.

Ch.2 Sec.5 A
1003   The under-thickness tolerance acceptable for classification shall be considered as the lower limit of a 'plus-minus' range of thickness tolerances which could be found in the normal production of a plant producing rolled or extruded products, on average, to the nominal thickness.

Ch.2 Sec.5
A 1100   Repair

Ch.2 Sec.5 A
1101   Surface imperfections may be removed by machining or grinding provided the final dimensions are within the tolerances. Repair by welding is not permitted.

Ch.2 Sec.5
A 1200   Identification

Ch.2 Sec.5 A
1201   Each item which has been tested and inspected with satisfactory results shall be suitably identified by the manufacturer with the following:
—manufacturer's name or trade mark
—alloy grade and temper condition
—identification number, heat number or other marking which will enable the full history of the product to be traced.


Ch.2 Sec.5 A
1202   Where a number of items are securely fastened together in bundles, only the top item of each bundle need to be branded. Alternatively, a durable label may be attached to each bundle.

Ch.2 Sec.5
A 1300   Certification

Ch.2 Sec.5 A
1301   The manufacturer shall provide the type of inspection certificate required in the relevant construction rules giving the following particulars for each test unit which has been accepted:
—purchaser's name, order number and vessel identification, where known
—manufacturer's name
—number, dimensions and mass of the product
—alloy grade and temper condition
—identification marking
—chemical composition
—results of mechanical tests
—results of any supplementary and additional test requirements specified.

For Temper descriptions reference is made to the standards in A 201.

Ch.2 Sec.5 A
Table A1 Chemical composition limits 1) for wrought aluminium alloys  
Grade  Si  Fe  Cu  Mn  Mg  Cr  Zn  Ti  Other elements 2)  
Each  Total 
NV-5052  0.25  0.40  0.10  0.10  2.2 - 2.8  0.15 - 0.35  0.10  -  0.05 0.15  
NV-5059  0.45  0.50  0.25  0.6 - 1.2  5.0 - 6.0  0.25  0.40 - 0.9  0.20  0.05 5)  0.15 5)  
NV-5083  0.40  0.40  0.10  0.40 - 1.0  4.0 - 4.9  0.05 - 0.25  0.25  0.15  0.05  0.15  
NV-5086  0.40  0.50  0.10  0.20 - 0.7  3.5 - 4.5  0.05 - 0.25  0.25  0.15  0.05  0.15  
NV-5154A  0.50  0.50  0.10  0.50  3.1 - 3.9  0.25  0.20  0.20  0.05  0.15  
NV-5383  0.25  0.25  0.20  0.7 - 1.0  4.0 - 5.2  0.25  0.40  0.15  0.05 4)  0.15 4)  
NV-5454  0.25  0.40  0.10  0.50 - 1.0  2.4 - 3.0  0.05 - 0.20  0.25  0.20  0.05  0.15  
NV-5456 0.25 0.40 0.10 0.50-1.0 4.7-5.5 0.05-0.20 0.25 0.20 0.05 0.15 
NV-5754  0.40  0.40  0.10  0.50 3)  2.6 - 3.6  0.30 3)  0.20  0.15  0.05  0.15  
NV-6005A  0.50 - 0.9  0.35  0.30  0.50 6)  0.40 - 0.7  0.30 6)  0.20  0.10  0.05  0.15  
NV-6060  0.30 - 0.6  0.10 - 0.30  0.10  0.10  0.35 - 0.6  0.05  0.15  0.10  0.05  0.15  
NV-6061  0.40 - 0.8  0.7  0.15 - 0.40  0.15  0.8 - 1.2  0.04 - 0.35  0.25  0.15  0.05  0.15  
NV-6063  0.20 - 0.6  0.35  0.10  0.10  0.45 - 0.9  0.10  0.10  0.10  0.05  0.15  
NV-6082  0.7 - 1.3  0.50  0.10  0.40 - 1.0  0.6 - 1.2  0.25  0.20  0.10  0.05  0.15  
  1. Composition in percentage mass by mass maximum unless shown as a range or as a minimum.
  2. Includes Ni, Ga, V and listed elements for which no specific limit is shown. Regular analysis need not be made.
  3. Mn + Cr: 0.10-0.60.
  4. Zr: maximum 0.20. The total for other elements does not include Zirconium.
  5. Zr: 0.05-0.25. The total for other elements does not include Zirconium.
  6. Mn + Cr: 0.12-0.50.
 

Ch.2 Sec.5 A
Table A2 Mechanical properties for rolled aluminium alloys  
Grade  Temper  Thickness, t(mm) Yield strengthRp0.2 min. or range(MPa)  Tensile strengthRm min. or range(MPa)  Elongation 1)  
A50 mm
min. (%)  		A5d
min. (%)  
NV-5052  0  t £ 50 65 165 - 215 19  18  
H32 t £ 6 130  210 - 260  10  
6 < t £ 50  130  210 - 260  12 12  
H34 t £ 6 150  230 - 280  7  
6 < t £ 50  150  230 - 280  9 9 
NV-5059  0  t £ 50 160  330   24 
H116 t £ 20 270  370  10  10 
20 < t £ 50  260 360 10 10 
H321 t £ 20 270  370  10  10 
20 < t £ 50  260 360 10 10 
NV-5083  0  t £ 50 125  275 - 350  16 14 
H112  t £ 50 125  275 12  10 
H116  t £ 50 215 305  10 10 
H321  t £ 50 215 - 295  305 - 385  12 10 
NV-5086  0  t £ 50 95 240 - 305  16 14 
H112 t £ 12.5 125  250 8  
12.5 < t £ 50  105 240  9 
H116 t £ 6.3 195 275 8  
6.3 < t £ 50  195 275 10 9 
NV-5154A  0  t £ 50 85 215 - 275  17  16 
H32 t £ 6 180  250 - 305  8  
6 < t £ 50  180  250 - 305  10  9  
H34  t £ 50 200  270 - 325  8  7  
NV-5383  0  t £ 50 145  290  17 
H116  t £ 50 220  305  10  10 
H321 t £ 50 220 305 10 10 
NV-5454  0  t £ 50 85 215 - 285  17  16  
H32 t £ 6 180  250 - 305  8  
6 < t £ 50  180  250 - 305  10 9 
H34  t £ 50 200  270 - 325  8  7  
NV-5456 0 t £ 6.3 130 - 205  290 - 365  16  
6.3 < t £ 50  125 - 205  285 - 360  16 14 
H116 t £ 30 230 315 10 10 
H321 30 < t £ 40  215 305  10 
40 < t £ 50  200 285  10 
t £ 12.5 230 - 315  315 - 405  12  
12.5 < t £ 40  215 - 305 305 - 385   10 
40 < t £ 50  200 - 295  285 - 370   10 
NV-5754  0  t £ 50  80  190 - 240  18  17  
H32 t £ 50  130 220 - 270  10 9 
H34 t £ 6 160 240 - 280  8  
6 < t £ 50  160 240 - 280  10 8 
  1. Elongation in 50 mm applies for thicknesses up to and including 12.5 mm and in 5d for thicknesses over 12.5 mm.
 

Ch.2 Sec.5 A
Table A3 Mechanical properties for extruded aluminium alloys 
Grade  Temper  Thickness, t(mm) Yield strengthRp0.2 min.(MPa)  Tensile strengthRm min. or range(MPa)  Elongation 1)  
A50 mm
min. (%)  		A5d
min. (%)  
NV-5059  H112  t £ 50 200  330  10  10  
NV-5083  0 t £ 50 110 270 - 350  14 12 
H111 t £ 50 165 275 12 10 
H112 t £ 50 110 270 12 10 
NV-5086  0 t £ 50 95 240 - 315  14 12 
H111 t £ 50 145 250 12 10 
H112 t £ 50 95 240 12 10 
NV-5383  0 t £ 50 145 290 17 17 
H111 t £ 50 145 290 17 17 
H112 t £ 50 190 310 13 13 
NV-6005A  T4 t £ 50 90 180 15 13 
T5 t £ 50 215 260 9 8 
T6 t £ 10 215 260 8 6 
10 < t £ 50  200 250 8 6 
NV-6060  T4 t £ 50 60  120  16  14  
T5 t £ 50 100  140  8  6  
T6 t £ 50 140  170  8  6  
NV-6061  T4  t £ 50 110  180  15  13  
T5  t £ 50 205  240  6  7  
T6  t £ 50 240  260  10  8  
NV-6063  T4  t £ 50 65  130  14  12  
T5  t £ 50 110  150  8  7  
T6  t £ 50 170  205  10  9  
NV-6082  T4  t £ 0 110  205  14  12  
T5  t £ 50 230 270 8 6 
T6 t £ 5 250  290  6  
5 < t £ 50  260  310  10 8 
1) Elongation in 50 mm applies for thicknesses up to and including 12.5 mm and in 5d for thicknesses over 12.5 mm. 

Ch.2 Sec.5 A
Table A4 Under-thickness tolerances for rolled products (mm) 
Nominal thickness, t (mm) Width of plate (w) (mm) 
w £ 1500 1500 < w £ 2000 2000 < w £ 3500 
3.0 £ t < 4.0 0.10 0.15 0.15 
4.0 £ t < 8.0 0.20 0.20 0.25 
8.0 £ t < 12.0 0.25 0.25 0.25 
12.0 £ t < 20.0 0.35 0.40 0.50 
20.0 £ t < 50.0 0.45 0.50 0.65 

Ch.2 Sec.5 A
Table A5 Under-thickness tolerances for extrusions (mm)  
Nominal thickness range, t (mm) Open profiles, sections circumscribed by a circle of diameter, d (mm) Closed profiles 
d £ 250 250 < d £ 400 d > 400 
3.0 £ t < 6.0 0.25 0.35 0.40 0.25 
6.0 £ t < 50.0 0.30 0.40 0.45 0.30 

Sec.5: Aluminium Alloys [Table of Contents] Sec.6: Testing Procedures