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| Aluminum oxide contamination is not any huge deal for that rusty yard artwork venture, however can wreak havoc on vital functions like an axle shaft. (Spider by John Lucas, Jr.) |
I’ve talked about weld contaminants in a earlier submit, however a current dialog satisfied me that it was a subject that warranted revisiting.
Aluminum oxide (AlO), specifically, is a nasty contaminant that’s oft missed.
What precisely is AlO? Fairly merely, it’s one of the vital frequent abrasives used. It’s current in most sandpaper, grinding disks, cutoff wheels, and even your favourite abrasive pads.
Why use AlO, and why is it so frequent? That, as properly, is easy. It’s low-cost, and it really works. It’s a unbelievable abrasive with low warmth retention, making it ideally fitted to all types of grinding processes.
Why is AlO an issue for welding? Ask a dozen welders, and also you’ll get a dozen solutions to this one.
Finally, the extent of the issue might be based mostly in your half traits. When you’re welding up some rusty yard artwork with a stick welder, you’re most likely not going to care that you just simply lower that shovel head and leaf spring with an AlO cutoff wheel. The residual contaminants from the dad or mum materials are going to infect the weld excess of the few embedded AlO particles.
Now, however, that alloy metal dragster axle shaft you’re about to have electron beam welded goes to care an entire lot about even the smallest defect. You may assume that a few seemingly inconsequential grains of AlO abrasive couldn’t potential make the distinction between a mid 5 second run and hitting the wall at breakneck speeds. That may be a harmful assumption.
AlO melts at almost 4,000 levels (F), whereas metal melts at underneath 3,000 levels (F). That signifies that these particles have the potential to take a seat buried within the resolidified weld as brittle little factors of failure. No quantity of post-weld warmth therapy will scale back how brittle they’re.
Now, let’s assume that we DO get the weld scorching sufficient to soften the AlO particles. That needs to be OK, proper? Not likely. AlO is, as implied within the title, Aluminum and Oxygen, each of which might be liberated with adequate warmth. Neither of which you need in your metal.
As welders, we take excessive care to forestall the introduction of oxygen into our weldments. There are complete lessons devoted to this. For this weblog, let’s simply say oxygen is unhealthy, mmm kay?
Aluminum can also be one thing not fascinating in metal. It kinds brittle intermetallics which will or could not present up as weld defects. They WILL current within the type of surprising power and toughness traits.
One different manner AlO can get you is by evaporating, however not dissolving into the dad or mum materials, inflicting porosity. Once more, on your metal backyard statue, no downside. For that axle, the outcomes may very well be anyplace from embarrassing to straight-up harmful.
What’s the different? There are heaps, but when abrasives are in your plan, contemplate Silicon Carbide as your ultimate abrasive.
For extra particulars, attain out to an professional to go over some nice choices on your subsequent inventive or excessive velocity enterprise. It’s also possible to go away a query or remark within the house under.
