Section 4 Welding procedure tests for non-ferrous alloys

4.1.1 The requirements for welding procedure qualification tests for aluminium alloys are to be in accordance with the general requirements of Ch 12, 2 Welding procedure qualification tests for steels with the following exceptions and specific requirements.

4.1.2 Non-destructive examination is to be performed in accordance with Ch 12, 2.5 Non-destructive examination (NDE) and the assessment of results is to be in accordance with Table 12.4.1 Acceptance criteria for surface imperfections of aluminium alloys and Table 12.4.2 Acceptance criteria for internal imperfections of aluminium alloys.

4.1.3 Acceptance of the mechanical tests is to be in accordance with Ch 11, 9 Consumables for welding aluminium alloys. Welding of the strain hardened and heat treatable aluminium alloys will generally result in a loss of tensile strength in the heat affected zone below that specified for the base materials and the tensile strength acceptance criteria to be applied is that specified for the material in the annealed or 'as fabricated' condition. Minimum values of tensile strength measured on the transverse tensile samples are given in Table 12.4.3 Tensile strength requirements by grade for aluminium alloys.

4.1.4 Impact tests and hardness surveys are not required for aluminium alloys.

4.1.5 Four side bend tests may be used in place of root and face bends where the test thickness exceeds 12 mm, and longitudinal bend tests may be used instead of transverse tests where the test weld is between different grades of alloy. Bend specimens are to be bent round a former in accordance with Table 11.9.1 Requirements for butt weld tests in Chapter 11, with the exception that the 6000 series alloys may be bent round a former with D/t = 7.

4.1.6 The ranges of approval to be applied to the WPS are to be as specified for steel in Ch 12, 2.15 Range of approval with the following exceptions:

1. The welding positions approved are as detailed in Table 12.4.4 Welding procedure approval, welding positions for aluminium alloys.

2. The aluminium alloys are grouped into three groups as follows:

   • Group A: aluminium-magnesium alloys, with Mg content ≤3,5 per cent (alloy 5754).
   • Group B: aluminium-magnesium alloys with 4 per cent ≤Mg ≤5,6 per cent (alloys 5059, 5083, 5086, 5383 and 5456).
   • Group C: aluminium-magnesium-silicon alloys (alloys 6005A, 6061 and 6082).

   For each group, the qualification made on one alloy qualifies the procedure also for the other alloys in the group, with equal or lower tensile strength after welding. The qualification made on group B alloys qualifies the procedure for Group A alloys also. Approval for the range of material grades is summarised in Table 12.4.5 Welding procedure approval, aluminium material grades approved.

3. The qualification of a procedure carried out on a test assembly of thickness t is valid for the thickness range given in Table 12.4.6 Range of qualification for parent material thickness. In the case of butt joints between dissimilar thicknesses, t is the thickness of the thinner material. In the case of fillet joints between dissimilar thicknesses, t is the thickness of the thicker material. In addition to the requirements of Table 12.4.6 Range of qualification for parent material thickness, the range of the qualification of throat thickness of fillet welds, a, is given in Table 12.4.7 Range of qualification of throat thickness for fillet welds. Where a fillet weld is qualified by a butt weld test, the throat thickness range qualified is to be based on the thickness of the deposited weld metal.

4. The range of shielding gas compositions approved is to be in accordance with Table 11.9.2 Shielding gas compositions in Ch 11 Approval of Welding Consumables.

5. A change in the brand or trade name of the filler metal from that used in the test is acceptable, provided that the proposed consumable has the same or higher strength grading.

6. A change in post-weld heat treatment or ageing is not permitted, except that for the heat treatable alloys, artificial ageing may give approval for prolonged natural ageing.

4.2.1 The requirements for welding procedure qualification tests for copper alloys are to be in accordance with the requirements for steel as given in Ch 12, 2 Welding procedure qualification tests for steels with the following exceptions and additions.

4.2.2 Impact tests on copper alloys are not required.

4.2.3 Hardness tests are not required for seawater service.

4.2.4 For the welding of cast copper alloys for propellers, the minimum tensile strength from the transverse tensile test is to be in accordance with Table 12.4.8 Minimum transverse tensile strengths for welded copper alloy propellers .

4.2.5 Bend tests are to be performed over a diameter of former as detailed in Table 12.4.9 Former diameters for bend testing of copper alloy welds.

4.2.6 The range of approval to be applied to the WPS is to be as specified in Ch 12, 2.15 Range of approval with the exception of the material grades which are detailed in Table 12.4.10 Range of approval for copper alloy material grades.