PROPERTIES OF WELDED ALUMINUM

[jamesh8448]

How much reduction in yield strength is needed for the heat affected zone of welded 6061-T6. How large is this annealed area? I typically do not work with aluminum, and I do not have easy access to aluminum specs.

 

[boo1]

Depending on the filler rod alloy the yield strength is reduced from 40 ksi to 18 ksi(4043 alloy rod) or 19 ksi (5356 alloy rod).

The heat effected zone depends on weld technique, amperage, base metal thickness. (possibly 1/4" to 1 inch)

 

[bnrg]

ASM handbook 6 (welding) has a chart (table 8 in welding of alum alloy chapter) that lists as welded strengths and post weld heat treat and age of various alum alloys.
6061-T6 welded using 4043 filler has as welded ultimate tensile strength of 37 ksi, yield is 20 ksi. If post weld heat treated and aged it changes to 43 and 40 respectively or pretty much what it was before welding. This data is for a .25" thick section. They list no data for thicker sections.
6061-T6 welded using 4643 filler is recommended for sections over .75" thick. As welded (in a 3" thick plate) this had 27 ksi tensile and 14 ksi yield. Post weld with heat treat and age has 45 and 40 ksi respectively.
Hope this helps,
Bob

 

[CWIC]

The AWS D1.2:2003 Structural Welding Code-Aluminum requires a minimum as-welded tensile value of 24ksi for 6061 T6 alloys. This includes plate, sheet forgings, etc.

 

[drawoh]

Are you guys talking about the Aluminium 6061-T6, alloyed with silicon and magnesium, that has been solution heat treated and artificially aged?

After you weld, you have Aluminium 6061-0 at the weld, which has a yield strength of 8ksi.

I have a chart here in an old catalogue that lists a yield stress of 14ksi for Aluminium 6061-T6 and 4043 filler alloy. If I were serious about all this, I would send my weldment out for heat treatment when I was done.

I have not read a really clear article on how aluminium heat treating works, so I am prepared to be corrected on this.

JHG

 

[kenvlach]

If you are going to post-weld heat treat to restore the T6 properties, a heat-treatable filler such as 4643 is necessary. See "What filler metal to use when welding 6061-T6 base material" at

http://www.alcotec.com/techpage.htm

drawoh,
The weld metal is in an 'as cast' rather than the annealed temper, and is likely under residual tensile stress owing to contraction after solidification. The HAZ has a series of undefined tempers ending in T4, which gradually transitions to the unaffected T6 base material.