Want to test if aluminum is ductile or brittle? Learn why Charpy testing is not irrelevant and won't get you the answers you're looking for. Find out more here.

Q: I’ve seen various references to aluminum-scandium (AlSc) alloys. Apparently, the addition of scandium makes aluminum alloys stronger. But I never see these alloys used in common welded fabrication. Why? Can I weld them? A: The major aluminum companies experimented with Sc additions to a lot...

Q: There seems to be a lot of controversy about what size contact tip to use for GMAW aluminum. Can you give me any advice? A: The contact tip has two functions. First, it provides guidance for the welding wire. Second, it provides a means of conducting welding current from the welding torch...

Q: What is anodizing? Is it the same as hardcoating, and can I do it myself? Can you weld on anodized parts? A: Anodizing is a process in which a thin, uniform coating of aluminum oxide is formed on the surface of aluminum. Any aluminum alloy can be anodized, but different alloys form anodized...

Q: We are welding 6061-T6 that is ¼ in. to 1 in. thick. To weld the thicker materials we are preheating to 300 to 600 degrees F. We are not happy with the strength of the welds. Is there something we can do, such as heat treating after welding, to increase the strength of the weld? A: You can...

Q: I’m confused about various aluminum filler metal strengths. Does the filler designation tell me anything about the strength of the filler or the weld? I looked in AWS A5.10, the specification for aluminum GMAW and GTAW filler metals, and there are no strength requirements even in there. Why?...

Q: I’m trying to weld some very thick aluminum mold plate. I don’t know what the alloy is. The plate thickness is about 12 in. I’m having lots of cracking problems. Can you tell me what the problem might be? A: In the way of background, most of the molds used for injection or blow molding...

Q: I’m having a lot of problems with porosity in my aluminum welds. Can you tell me what’s causing it? A: As we’ve said before, all porosity in aluminum welds is caused by hydrogen, which is very soluble in molten aluminum but insoluble in solid aluminum. Generally, hydrogen comes from two...

Q: I get a lot of black smoke on the surface of my aluminum welds. What is it, and how can I get rid of it? A: I can tell you what the black smoke isn’t. It is not soot and it doesn’t contain carbon, as most people think. It is, in fact, a mixture of very fine particles of aluminum oxide and...

Experiencing arc bowing during aluminum welds? Our experts explain what causes arc blow and what you can do to mitigate it when welding aluminum.

Q: I weld a lot of aluminum castings. Most of the time they weld fine, but sometimes the weld blows out at me. What’s going on? A: The problem is caused by the casting process. There are three types of casting processes—sand casting, permanent mold casting, and die casting. The molds for sand...

Q: I am trying to conduct a procedure qualification test on 5083-0 temper material using 5356 filler metal and gas metal arc welding (GMAW). I have welded a number of test plates, but the tensile samples always fail at a tensile strength of 37 to 39 KSI. The code requires a minimum tensile strength...

Q: What is the right contact tip size for using 0.0468-in. filler wire to gas metal arc weld aluminum alloys? Some people use a tip that is one size larger (for example, a 0.0625-in. tip on 0.0468-in. wire), while others use the size the manufacturer specifies for 0.0468-in. wire. Still others use...

Is welding aluminum toxic? Find out if the welding fumes in aluminum MIG are dangerous and if there are other issues with fumes to be aware of.

Are push-pull guns for aluminum welding necessary? Find out if you need a push-pull mig gun or if a standard gun with a Teflon® liner and contact tips will work.