Squished Gregor - Last Rites

[Richas]

Hi,
You can see from the attached pictures that our little Gregor boat was squished by a falling tree. Before I haul it off for scrap metal I though I would check with the aluminum experts, to see if anything can be done. I am a very handy, very DIY person so my first inclination is to try to fix it, but I don't want to waste my time either. I know you can soften/anneal aluminum with an acetylene torch, perhaps this would allow re-shaping? If this could work how would I re-harden the metal?

I would appreciate it if I could get some expert advice on this, whether it is worth the attempt or if it is scrap yard time. This boat has sentimental value some there is some justification for extra effort if there is any hope.

Thank you

Rich

 

[jehardiman]

In the shipyard or a well equipped sheet metal/body shop we could probably set it workably right. That's going to require some hydraulic rams/presses as well a some hammer and dolly work. Not really backyard work.
FWIW, as you work aluminum it becomes work hardened. You heat (very gently, you're not trying to soften it) and anneal it to recrystallize the grain boundaries to prevent work tearing. Most sheet aluminums will age harden at room temperature, and I doubt that the skin of a small boat was ever tempered.
6061 aluminum alloy - Wikipedia https://en.wikipedia.org/wiki/6061_aluminum_alloy

EDIT to add:
A quick look through Gregor literature show that the smaller hulls (i.e. model U-12 https://gregorboats.com/wp-content/uploads/2018/02/U-Series-2017.doc.pdf ) are made of 5052 and 6063 I would bet the skin is 5052 and the extrusions are 6063. 5052 is a work hardening alloy which ideal for a sheet formed boat. The 6063 is a solution hardened alloy for the extruded/formed shapes used in the gunnel, etc.
5052 Aluminum - 5052 Aluminum Properties - Ryerson https://www.ryerson.com/resource/the-gauge/grade-anatomy-aluminum-5052
Aluminum Structural Shapes Supplier - Ryerson https://www.ryerson.com/catalog/101118

 

[Ad Hoc]

....FWIW, as you work aluminum it becomes work hardened. ...

The 5000 series yes.
One does not strain harden 6000 series, unless under very struct controlled conditions.

... You heat (very gently, you're not trying to soften it) and anneal it to recrystallize the grain boundaries to prevent work tearing. ...

Not sure what you're referring to here.l
But in general, one should never heat aluminium ...ever!
For the reasons you cited, it anneals, but can be very detrimental on the wrong grade and temper.

... Most sheet aluminums will age harden at room temperature,...

Again, that only applicable to 6000 series and those which have already undergone super saturated solid solution (SSSS) treatment to improve its properties.
Since the quenching produces the SSSS to begin with, which is then either naturally aged or artificially aged at a much lower temp to obtain the super saturated solution. Thus, if you heat this, you loose the SSSS and the initial gain in strength. The natural age hardening alone (without the SSSS) will produce a lower strength material than the initially SSSS.

... 5052 is a work hardening alloy ..

Any 5000 series alloy can be strain hardened.
You just need to check the temper before you buy!

 

[jehardiman]

AH, I'm just trying to be helpful... not wring the last psi out of a structure.
A FRICKING TREE fell on a 12 ft aluminum boat! Both you and I know that more work is required to repair than to build new.
Could a good crew heat it and beat it back into rough shape?...most likely yes. But not someone unexposed to the material.
Would it structurally the same?...most likely not.
Would it function? ... most likely yes. But not look very good.
Do both 5000 and 6000 series Al age harden at room temperature? ... yes, because the hardening (and all the favorable and detrimental effects) has both temperature and flexure portions.
Anyway...did I mention it's a 12 ft aluminum boat? We are are not discussing the BEN FRANKLIN or ALUMINAUT.

 

[Ad Hoc]

AH, I'm just trying to be helpful... ...

Indeed, as you always are

The problem is, as well you know, the arm chairs wannabes, take the "basic" guide, that you've outlined above, and use that as the gold standard for ALL applications, and incorrectly apply them.
Im just trying to avoid those not versed in the finer points of aluminium, to treat such comments as - all things to all grades/temps - and unaware of the pitfalls of doing such!

..Do both 5000 and 6000 series Al age harden at room temperature? ... yes,...

But that's a no.
You can't age harden 5000 series. Because you can't control the precipitates, they way you can with 6000 series, these being the Mg2Al3 precipitates in the general 5000 series, in a nut shell.

 

[jehardiman]

But that's a no.
You can't age harden 5000 series. Because you can't control the precipitates, they way you can with 6000 series, these being the Mg2Al3 precipitates in the general 5000 series, in a nut shell.

Just because you can't control it doesn't mean it doesn't happen. Is it significant? <shrug>. All I know is old, used 5000 series has much more rework issues. Oxide layers? Worked grain boundaries? We had 5000 series stuff never overloaded that failed during routine ops that showed all the signs of brittle fatigue. Anyway, this would be a lot of heat, beat, and pray.

 

[Ad Hoc]

.... Oxide layers? Worked grain boundaries? We had 5000 series stuff never overloaded that failed during routine ops that showed all the signs of brittle fatigue. ...

Ooohh.. there is a lot in that one.
What do you mean by - rework issues??

It is hard to say without visibility of "whatever" occurred and knowing the alloy grades and temper and how it was fabricated and then its duty etc.
But...ally, doesn't failure in a brittle nature - it is a ductile material.
In very very verryyyyy extreme circumstances one could "force" it to, but in general, it is always ductile failure.
There has been "some" evidence in 7000 series, at grain boundaries of welds, i.e microscopically etc.. but that is for a whole different reason, but i digress.
Many confuse brittle with shear failures.

 

[jehardiman]

Ooohh.. there is a lot in that one.
What do you mean by - rework issues??

Nah...this one had all the signs; passed a recent PT but had chevrons, not under load at failure...rework was re-bolting and having issues with torque (we bolted, not welded), trying to get everything aligned after re-furb, 10+ years since OIC, many pressure cycles. Lab FA was cycle fatigue/work hardening. <shrug> Formed 5250 half-hard IIRC. Selected for strength, corrosion, and toughness. Not my item, but one I had to load test...so was very involved.

 

[jehardiman]

Hi, <snip>
I would appreciate it if I could get some expert advice on this, whether it is worth the attempt or if it is scrap yard time.

Sorry about topic drift, so I'll let Ad Hoc weigh in on this, but as we have implied, this is not an easy fix. As you can see lots of issues with the exact materials.

 

[Ad Hoc]

..I would appreciate it if I could get some expert advice on this, ...

If you're not going out deep or being silly with this, then just get a good sheetmetal worker to "bash" out the deformation....if possible, and without making it worse!
And call it a day..

Don't add any heat.

 

[Tiny Turnip]

Maybe you could run the tree through a mill and make a new boat out of it by way of revenge / encourager les autres

 

[gonzo]

If you don't care about looks, some wooden blocks to support it and a sledge hammer will make it useable.

 

[rnlock]

Friends of mine rented an aluminum canoe and got it all bashed up in mild whitewater. According to their story, if I remember it right, one of them got in a tree over the canoe and jumped into it to push it back into shape. Of course they ended up buying the canoe, because it looked a little rough. I borrowed the canoe later. It worked fine as long as you didn't look at it. I don't recommend this kind of jumping.

Looks to me like that boat is usable as is, as long as you don't use much power.

I'm guessing that it would be fine* after bending it back as much as possible, except maybe the gunwhale will need a bit of reinforcing with another piece of aluminum. Did I spell that right? I wonder if an auto body place might be set to straighten this out? I remember my Dad taking his Chevelle to a guy who specialized in pulling cars straight.

*Might not look fine if you stood too close.