MIL-R-45774 Radiographic Inspection, Soundness Requirements For Fusion Welds In Aluminum And Magnesium Missile ComponentsThis specification covers the methods for defining soundness and freedom from defects of manual or automatic shielded inert gas arc welds in aluminum and magnesium as determined by radiographic inspection.

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MIL-R-45774A  (MI)

4.4.5  Rule  5.  Imperfect fusion and incomplete penetration defects occur when the molten weld metal fails to fuse due to oxide or other impurities, or when the

molten metal fails to penetrate the full thickness of the sheet due to insufficient heat. These defects shall be graded according to rules 1 and 2 and figures 1 and 2.

4.4.5.1  Fillet welds.  Acceptability limits for imperfect fusion at weld interface for standard III (see figure 3) fillet welds shall be in accordance with the referenced radiographs (see table I).  Because of the difficulty in differentiating between incomplete penetration and imperfect fusion in fillet welds, either or both conditions shall be cause for rejection if in excess of the limits shown in the referenced radiographs.

4.4.5.2  Butt welds with back-up-strips.  Acceptability limits for imperfect fusion at weld interface for standard II (see table IV) butt welds shall be in accordance with the referenced radiographs (see table I).

4.4.6  Rule  6  -  Foreign materials.  More dense inclusions in aluminum arc welds are usually present in the form of tungsten from the electrode (TIG).  Less dense inclusions are generally impurities resulting from poor cleaning, improper shielding

gas mixture or pressures  (see table I).

4.4.7  Rule  7  -  Undercutting.  Undercutting shall be cause for rejection if greater than of O.1OT in depth for any 1 inch weld length.  Undercutting may be observed on the radiographs but is measured by mechanical means (see table I).

4.5  Special rules applicable to use of back-up-strips.

4.5.1  Sheet thickness - determination.  For purposes of determining acceptability limits of welds with back-up-strips, the thickness (T) shall be defined as the thickness of the thinner sheet being jointed.

4.5.2  Isolated voids.  In reference to Paragraph 4.4.3.1, isolated voids shall be cause for rejection if the diameter of the void is in excess of O.66T.

5.  PACKAGING

5.1  There are no applicable requirements for packaging.

6.  NOTES

(This section contains information of a general or explanatory nature that may be helpful, but is not mandatory.)

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