another way to determine if its aluminum

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Hi,Just wondering if anybody new a way to determine if something is aluminum or not? Its a cargo hauler from Princess Auto (princessauto.ca) that fits into the 2" receiver in the back of my jeep. It says it is constructed of metal, but its hard to tell.I know weight is usually a good way to tell if its aluminum, because its lighter, but is there another way to tell?There was a thread just before this one about not being able to weld steel and aluminum together (through fusion), but what would happen if you tried using GMAW/FCAW?I'm asking because I tried to weld a 'shim' to the top of the tube that fits in the hitch, because its bouncing all over the place (not a snug fit that I believe is a problem with the hitch, not the tube). My welds were horrible, after I thought I was getting better. Its like I went back to starting over (...a week and a half ago...lol). The arc seemed weeker too, and stopped and started a lot more. I did grind it well till there was not paint. Perhaps metal with a lot of impurities? Probably as simple as not enough experiece...not the correct settings. But, through the process of elimination, I want to figure out what i've done wrong. I think I was trying to weld about 16 gauage to about 14 or 12 gauge, using FCAW.homsted
Reply:You've put a magnet to the insert right??
Reply:nope. I just picked up magnets last night, so I'll try that test tonight. Thanks Sandy!I feel kind of stupid.
Reply:If a magnet sticks to the metal, that tells you that you have steel or some ferro-magnetic material.  It could be plain steel, high-carbon steel, stainless steel, cast iron, nickel, etc.  But it won't be aluminum.If the magnet doesn't stick to the metal, it could be stainless steel, or aluminum, or zinc, or some other metal or alloy, or plastic.Cargo hauler that fit's into a 2 inch receiver hitch?  Looks like a shelf about 2ftx4ft or so, has a weight rating of about 500 pounds?  Then that metal piece that fits into the 2 inch receiver hitch is steel.  No, you can't weld aluminum and steel together.  Not in the common sense of weld as in "to join parts together by melting the seam/joint and optionally adding filler material".  Steel melts at around 1500F, aluminum around 1000F.  And the two metals don't really dissolve together when melted, except for small amounts going into the 'other' metal.To join dissimilar metals like aluminum to steel, you would have to go to an 'exotic' process like friction welding or explosive welding, or rivets or bolts, etc.If the receiver and the tube are loose and sloppy, I'd just shim it but wouldn't weld up the tube.  Unless the tube was waaaaay undersized.  If you make a tube bigger to fit an oversized hole in the receiver, then it may not fit a right-sized receiver.You aren't trying to put a 1-1/4 inch cargo carrier into a 2 inch receiver, are you?
Reply:Originally Posted by homstedI feel kind of stupid.
Reply:No, its not 1 1/4". It says it fits all 2" receivers. Trailers have the same problem with this hole, they have to much play, and actually make a lot of noise because of it. I had somebody at work recommend to me that if joining the 2 pieces together isn't working well, then perhaps just build up the tube of the hauler by running some beads (i should have thought of that since that's what i've been practicing for the past week), then grind them smooth. I think i'll try that, and see what happens. If i ruin the tube its not the end of the world, because the rack bolts onto the tube. So I have some 2"x2" tube in the garage that I can drill holes in, and replace the tube that I destroyed.I'll try and take a picture and post it.Sandy, lol....I hate when something clicks, but its the mouse hitting the "Submit Reply" instead of my brain. Cheers!homsted
Reply:That's what I had to do with my bicycle rack that I built to fit the 1.25" receiver on my VW.  Even though the tubing was already snug it had play under load.  Added 4 small beads on the corners and ground them down to where they'd fit really snug.  No more rattle.ThermalArc 185MillerMatic 180 w/ AutosetVictor Cutskill Oxy/AcetyleneThermal Dynamics Cutmaster 38and spite!