Shot Peening vs Oven baking/Heat treatment

[RHam]

Afternoon All,

I hope you are all well?

I have built a few electric bikes over the years and on this current build I would love to customise my full suspension t6061 aluminium frame (mega chunky orange patriot 7+) for housing a battery (part of the reason i started my level 2 welding course last year in fact), however, I am told various things by various well qualified and experienced folks about the situation post welding....

Welding will weaken the frame in and around the HAZ of the welds...I have heard up to 70% loss of yield strength but most research I found shows 50%.

options so far as I can tell are:

1) meh it's only a bike frame and overbuilt anyway so just run it as welded and it hopefully will be fine
2) it definitely needs baking and quenching by pros which a) sounds expensive and b) will need to putting in a jig to prevent deformation
3) shot peening appears on the surface (no pun intended) to be a half way place between baking it and leaving it as welded as it returns about 10% of the yield strength and increases fatigue life post weld as well as baking it does. Also it seems much much cheaper without the need for being in a jig to prevent deformation....this is my preferred route if it can work.

I have spoken with bike manufacturers, local engineers and an aircraft engineer and tool maker and all have different opinions from it'll be fine as welded to yes it definitely needs baking and quenching....which obviously leaves me confused...

Any help, experience or thoughts on any of this is much appreciated...

Thanks guys

 

[RHam]

If it makes a difference I would like it to be the downtube I remove and modify with a custom battery box...one side or the bottom would need to be a removable panel I think to access and remove the battery if that makes any difference at all....

 

[RHam]

Hmmm 80% you say, on it's own over time...that could work...what kind of time frame are we talking here? I assume that that peening would only help the situation too...

Thanks for the speedy input and book suggestion

 

[RHam]

Interesting, well I guess that is good news for me...I can live with 80% of pre weld strength with a few gussets and liberal use of filler. Speaking of filler...I have been using 4043 filler with all my TIG work to date...would you advise a different filler?

Thanks again

 

[Tangledfeet]

...full suspension t6061 aluminium frame (mega chunky orange patriot 7+)...

That's a downhill bike and I suspect you are wanting to put the battery in the large, folded downtube?

Whilst I admire your intentions, personally I value my teeth, limbs and handsome looks... no way I'd go wanting to mess with such a major structural part of the bike and then ride it off road!

(Seeing Steve Peat win Fort Bill on an Orange was something I'll never forget!)

 

[RHam]

"Silicon doesn’t heat treat hence my mention of filler." You've lost me a little there...are you suggesting 4043 is not a good choice and perhaps 4047 or another...apologies I am no engineer so the details evade me for now...

 

[RHam]

Yes Tangledfeet it is a burly bike for being abused for sure. Watching any redbull rampage is mind boggling for me. I am so far from that caliber of riding though and have zero intention of launching large jumps or dropping off dizzying heights....mostly cross country with small jumps over logs and the like!

The folded downtube is huge so i figure that would be a good place to work as i am told most stresses on the downtube are in one direction (remember the bike with the cable down tube)?

Initially i was wondering if the top tube were the better option but the down tube is bigger and a better location.

Part of my brain thinks i should just choose a frame with more space in the triangle so I can just build a case and strap it in but a) looks like **** and b) where is the fun in that?

 

[Tangledfeet]

...where is the fun in that?

Indeed!

I had an Orange Clockwork back in '93, my very first mountain bike; I think that was made in the UK - now they only make the folded alloy bikes here.

Yeah, I remember the bike with the cable! BUT, and this is a big 'but' for your project; one end of the shock is mounted on the down tube so in your case there isn't just one force acting on it...

 

[RHam]

The tentative idea was to leave the top half/third of the down tube in tact along it's length and weld on the battery housing to the lower half if that makes any sense at all. So whilst the tube itself will be weakened to whatever degree the heat from TIG causes the mounting for the shock itself would be untouched and like wise for the area near the swing arm pivot. But like I say I am no engineer so the forces involved may well be way too much to mess with down tube...advice welcomed from those in the know...

If the down tube is a no go for that reason then perhaps the top tube is an option again...

 

[hotponyshoes]

Is there any reason to be welding it on?
Could you not make up a box for the batteries (which you can tig solid you want) and then some method of clipping/clamping it on?
An advantage to a removable one would be that you could easily swap a flat pack for a fully charged one.
Or fit different size packs depending on how far you were going..

 

[RHam]

There is no where for it to go on in a clamped on form that i can wok out...

this is the frame...

https://ep1.pinkbike.org/p4pb3547417/p4pb3547417.jpg

 

[graffian]

A local heat treater had some idea about such things.
I asked about heat treating a motorbike frame, the answer was along the lines of:

*Bring us all the tube before its welded and we will anneal it, he mummbled about cracks in the haz of unannealed heat treated welded stuff?
*once the frame was made, make a light steel structure to support it during the solution heat treat.
*Solution heat treat
*Age

The rod to use was 5356.

I went with more gussetting and thicker tube instead of heat treating.
I only asked the one place, and always wondered if it was really like that.

Anyone want to know what the downtube is like there might well be a youtube video of them, Guy Martin went to
Orange for one of his TV programmes, he has a go at folding and welding a downtube.

Your intending on filling the downtube with batteries?
I would have thought sticking a door in the down tube to get things into it would be fine without a heat treat.

The cable down tube bike do you mean the breezer?
In something Joe breeze was writing in he wrote "nothing is new".
When the mountain bike museum was opening there were loads of old
photos of treaders at soem site associated with it, there was one photo of a group of blokes up on a mountain
somewhere, the picture looked really old, and one of the bikes has a cable downtube;-)

 

[RHam]

The battery is 32cm long, 8cm tall and 10cm wide....

 

[RHam]

Oooh i will have a look for the guy martin video...thank you.

I don't recall the name of the cable downtube bike i am afraid but it looked rubbish

The battery is larger than the current down tube so sadly not just a case of tucking them in

 

[graffian]

Stick it in your pocket and impress the girls.