SECTION III. M747 TRAILER RAMP

TB9-2510-242-40

no visible weld cracks in the base metal

all craters filled, except for ends of intermittent fillet welds outside of the effective length

replacement weld joints of the same type and size as the original weld

base metal repair welds achieve full thickness of the base metal

single continuous fillet welds may not underrun nominal specified fillet weld size by more than 1/16 inch

without correction, and the undersized portion may not exceed 10% of the weld

no underrun permitted at the ends of web-to-flange welds on girders, for a length equal to twice the width of

the flange.

for primary members, undercut shall not exceed 0.01 inch deep where weld is transverse to tension loading

stress under any design load condition

all other undercuts shall not exceed 1/32 inch -deep

minimum changes in cross section

minimum offsets in member alignment (a 3 to 1 taper in weld width will minimize the negative effects of

alignment offsets)

smooth, concave contour along the face of the weld

good weld penetration

3.1.9

Treat/Paint Repaired Joint.

Treat and paint welded joints, new material, and reinforcement plate areas according to the requirements of TACOM

Drawing Nol 19207-12344846-400, Treatment and Paint Spec for Tactical Vehicles and Components. Call DSN 786-

8278 if you need to obtain a copy of this drawing.

SECTION III. M747 TRAILER RAMP

4.1 WELDING PROCEDURES

4.1.1 Introduction to 6061 T6 aluminum . The chief alloying element of 6061 aluminum is magnesium-silicon. It is a

heat-treatable wrought aluminum alloy. The T6 suffix code indicates that the alloy is solution heat treated, then

artificially aged. The 6061 T6 alloy has a yield strength of 40,000 psi, ultimate strength of 45,000 psi, and Brinell

hardness of 95. Its mechanical properties increase as a result of heat treating. Some precautions are required when

welding to maintain these properties. In particular, care must be taken to not overheat the alloy since it has low melting

temperature. Weld cracking in aluminum is often due to the low strength and ductility of the weld metal used or of the

heat-affected zone as a result of elevated temperatures.

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