Welding 5000 Series Aluminum. Non-heat treatable aluminum alloys exhibit excellent weld ductility when using like filler alloys. The 5000-series alloys can be welded with or without any filler material while the 6000-series alloys need filler material to prevent shrinkage cracking generated during the solidification of the liquid weld pool.
X1xx represents the first modification to the specified alloy while x2xx represents the second modification. The alloy is not suitable for use in elevated temperature service. Among the aluminum alloys used for automotive body applications the 5000-series alloys have higher weldability than the 6000-series alloys.
These alloys are used primarily for structural applications in sheet or plate metals -- all 5000 series alloys are weldable 6000 series.
5000 Series aluminum is mixed with magnesium different than manganese and has both a high tensile strength and formability. The use of 5000 series has several advantages as well. As can be seen from the chart copper in aluminum alloys Al-Cu exhibits a. Lincoln suggests that if you have a need to design something of high strength aluminum look to a 5000 series high magnesium alloy instead of a 2000 or 7000 series.