Electrodes/Filler Metal Selection

TB9-2510-242-40

e. Clean surfaces. Cleanliness is critical to ensure good weld quality. Remove all paint, grease, scale, rust,

water, etc., for a distance of 4 inches around the new weld area. Remove paint from the back and inside of all

metal surfaces to be welded. Use mechanical or abrasive cleaning methods such as sandblasting, grinding, or

wire brush. When wire brushing is used, only new, degreased stainless steel wire is acceptable. Steel/iron or

brass/bronze must not be used because they create galvanic corrosion problems. Brushes previously used to

clean or prepare steel surfaces shall not be used.

4.1.4 Electrodes/Filler Metal Selection. The 6061 alloy is very susceptible to cracking. Use a filler metal of higher

alloy content than the parent metal to reduce weld cracking. Do not use 6061 filler metal. Filler metal with a melting

temperature below that of 6061 will reduce the shrinkage stress. The recommended filler metal is either Type 4043

(electrode type ER 4043) or 5356. Use 5356 for joints requiring a combination of strength and ductility, typically high-

stress joints. Use 4043 for low-stress joints and those joints requiring better corrosion resistance than 5356 or which

cannot accommodate any cracking.

4.1.5 Welding Process Selection. The welding process shall be either gas metal arc (GMAW) or gas tungsten arc

(GTAW).

4.1.6 Shielding Gas Selection . Argon, helium, or mixtures of argon and helium used for shielding shall be a welding

grade having a dew point of -63 degrees F or lower.

4.1.7 Preheat and Welding Heat Input . Excessive preheat and welding heat causes 6061 T6 aluminum to lose its

heat treated properties. Preheating is normally not required, except for thick sections. However, when the temperature

of the weld area and surrounding base metal is below the allowed minimum temperature, the base metal shall be

preheated so that the parts on which the weld metal is being deposited are at or above the minimum temperature for a

distance equal to the thickness of the parts being welded, but not less than 3 inches both laterally and in advance of the

welding. A controlled and moderate preheat can reduce the total required heat input, enhance weld penetration, and

avoid thermal stresses. Preheat temperatures for 6061 T6 should not exceed 300 degrees F. This heating is to be done

before welding is started and will also serve to drive moisture from the region of the weld. To prevent the metal from

distorting, use step welds and/or mufti-directional welds. Temperature indicating crayons or other pyrometric checks

should be used to monitor temperature.

4.1.8

Weld Profiles and Joint Requirements .

a. Aluminum joint designs are similar to steel joints. The faces of fillet welds may be slightly convex, flat or slightly

concave as shown in figure 4. With the exception of

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