Metallurgy: what aluminum filler metal for..

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My metallurgy instructor asked a question that he wanted to be researched.What is the best GTAW filler metal for aluminum for the following applications?Ductility:Tensile Strength:Corrosion Resistance:I am probably wrong but generally speaking I would guess:Ductility:5356Tensile Strength:5183Corrosion Resistance:5356Of course base metal would be a huge factor. (which I suspect might be actual answer)
Reply:I posted a response to someone having problems with 5356 wire when welding aluminum.  I stated that 5356 does have magnesium content and can make a mig weld look like chicken s*** on many grades of aluminum.  For the record, I keep in stock both 4043 (used the most) and 5356 (for different grades of aluminum that 4043 won't work well with).  Honestly, I can't remember the last time I used 5356 wire or filler rod.  Here is an item I pulled from Lincoln Electric.    Choosing Aluminum Wire by Lincoln's Aluminum Expert, Frank Armao  Frank Armao Within the walls of The Lincoln Electric Company are some of the brightest minds in welding, but we wouldn't be The Welding Experts® if it weren't for the expertise of our customers. Learn with us from questions submitted by real customers and answered by the real experts. When should I use 4043 and when should I use 5356?4043 is designed for welding 6xxx series aluminum alloys. It may also be used to weld 3xxx series alloys or 2xxx alloys. 4043 has a lower melting point and more fluidity than the 5xxx series filler alloys, and is preferred by most welders because it "wets and flows better" and it's less sensitive to weld cracking with the 6xxx series base alloys. 4043 can also be used for welding castings. 4043 also makes brighter looking MIG welds with less smut because it doesn't contain magnesium. 4043 gives more weld penetration than 5356, but produces welds with less ductility than those made using 5356. However, 4043 is not well suited for welding Al-Mg alloys and should not be used with high Mg content alloys such as 5083, 5086 or 5456 because excessive magnesium-silicide (Mg2Si) can develop in the weld structure to decrease ductility and increase crack sensitivity. (One exception to this rule is 5052, which has a low magnesium content.) 5356 wire has become the most commonly used of all aluminum filler alloys because of its good strength and its good feed-ability when used as a MIG electrode wire. It is designed to weld 5xxx series structural alloys and 6xxx series extrusions, basically anything other than castings, because castings are high in silicon. Its one limitation is that 5356 is not suitable for service temperatures exceeding 150 degrees Fahrenheit (65 degrees Celsius). The formation of Al2Mg at elevated temperatures at the grain boundaries makes the alloys prone to stress corrosion. For components that will be anodized after welding, 5356 is recommended over 4043, which turns jet black when anodized.
Reply:Personally, I tend to use 4043 on thin, and bended materials, or I will use a 1100 seires filler rod for stuff I have to bend a lot, like a sheet box or pan.. For strength, I use 5356. Between 4043 and 5356, I see 4043 giving me a more sandy looking bead, where 5356 is a bit smoother. 5356 does tend to show up finished with a little more blackening in the weld, especially if you don't clean the base material very well.And then, after so much work...... you have it in your hand, and you look over to your side...... and the runner has run off. Leaving you holding the prize, wondering when the runner will return.
Reply:As this is metallurgy coursework i'll point you in the right direction, YOU'RE supposed to be researching it. Yep, base material is important when considering filler material. Dilution also plays a part (think heavy sections versus thin) along with PWHT for the heat treatable alloys. Corrosion resistance... service environment has a role to play thereConsider 6061... the usual filler choice is 4043 but 5356 can be used and there is also 4643, designed specifically for 6xxx series Al that will undergo PWHT, especially thick sectionsAlcotec would be a good first call- as well as articles you'll find comprehensive filler selection charts for different alloys with regards to ease of welding, strength, ductility and corrosion'Key to non ferrous' has a lot of contentHave a play with google, for example 6061 welded with 4643, the first hit is ESABs education section (same or similar content to Alocotec)
Reply:Originally Posted by hotrodderAs this is metallurgy coursework i'll point you in the right direction, YOU'RE supposed to be researching it.
Reply:Thank you everyone for your replies I see this isn't going to be an easy question for me to answer.
Reply:http://www.alcotec.com/us/en/educati...um-Welding.cfmEd Conleyhttp://www.screamingbroccoli.com/MM252MM211 (Sold)Passport Plus & Spool gunLincoln SP135 Plus- (Gone to a good home)Klutch 120v Plasma cutterSO 2020 benderBeer in the fridge
Reply:Thanks! By reading posts that I looked through on here I had a pretty good guess as to who was going to post on this thread. Broccoli1, hotrodder, Rojodiablo, paweldor You all gave me some great advice and the resources you pointed me to were fantasic. I now have a 2 page report with what I researched before and I learned from you. I don't think anyone is going to have as much info as I will. (actually I don't think anyone else has probably started the research) You guys are great!