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Post by Admin on Nov 27, 2018 16:11:14 GMT -5
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Post by liteway on Nov 14, 2020 19:56:14 GMT -5
Have any of you guys ever tried joining aluminum sheet or bar using aluminum welding rods? I can make a joint of satisfactory strength for low stress applications with no problem but the aluminum is left so soft afterward the fabricated piece is useless.
I watched a dozen you tube tutorials on this and the problem is never mentioned and their metal appears still sound after it cools.
I am getting the metal no hotter than necessary to melt the rod.
I am aware there are procedures for rehardening, but they never seem to need them in the videos.
Any experience with this? Looking on the net it is as though I am the only one in the world with this problem.
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Post by fatherchuck53 on Nov 15, 2020 0:24:20 GMT -5
Been a lot of years ago. We would apply a layer of silver solder to the steel first and then come back and weld the aluminum to that with standard aluminum filler rod.
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Post by davej98002 on Nov 15, 2020 19:43:51 GMT -5
Lloyd, you heat aluminum to anneal it to bend/shape or weld it. It will age harden over time. Depending on the alloy it can be hours or weeks. Here is more information than most of us need. Not sure if it directly answers the question. llfurnace.com/blog/types-of-aluminum-heat-treatments/ |
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Post by liteway on Nov 15, 2020 21:16:09 GMT -5
Thanks Dave. I posted that just a few hours after some experiments with welding rods yesterday.
I was surprised to see, as you predicted, that the pieces were notably stiffer this morning than after cooling yesterday.
Maybe I can use this stuff after all if the soldered (brazed?) aluminum continues to stiffen over time.
I have to be careful when heating it though, to see that it is well supported as the aluminum sags easily.
Don't understand why the videos fail to mention all this.
Maybe the internet is not the "end all" after all.
On the positive side, if done carefully, it provides excellent bonding with a smooth finish and good color match (harbor freight stuff).
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Post by fatherchuck53 on Nov 20, 2020 23:48:44 GMT -5
I need to apologize, I read your post to say you were trying to join aluminum to steel.
When brazing aluminum over heating the brazen rod is very easy to do. You want to heat the base aluminum slowly and steadily probing with the filler rod. Just enough heat for the rod to melt and weep into the joint, no more.
Aluminum brazing rods have a high amount of zinc in them and when over heated the chemical and grain structures changes dramatically and there is no cure for it except cutting it out and starting over.
You mention using Harbor Freight rods. I would judge by their quoted melting temp they have an even higher zinc content [6-7%] and are by nature weaker and softer. Great for practicing with and affordable. An almost as inexpensive readily available version are those sold in most all you big box hardware stores. They take a little more finesse to use but are lower in zinc and will be far stronger.
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