DH frame repairs

[r.hendrix]

I have recently had a crack in my izimu frame repaired (swing arm) welded up nicely, the company i sent it to reckons its not nesessary to hear treat it post weld, although many people say that hear treating is essential. Can it be heat treated post weld or should I just leave it as is and see how far I get? Any advice would be appreciated

[Cruz Addict]

I am no engineer by any means but as far as I have been told a welded area is 9 times out of 10 stronger than a non welded area, I suppose the rational thought process is that there is more metal bonded together to make the weld and so it's stronger, my humble 2c would be if you are going to grind the weld flat etc for repaying then yes try do a heat treatment but if you are happy with a paint job covering a weld( for your sake I hope it's a nice tight neat one) then leave be and just go ride

[Guest Omega Man]

My advice is to not listen to all of the "experts" on a forum and rather phone Morewood for advice.

[DJR]

My advice is to not listen to all of the "experts" on a forum and rather phone Morewood for advice.

 

Now THAT is good advice

[Firozfx]

I am metallurgical engineer. Steel was my thing. Steel is made up of 3 dimensional perfectly fitting grains, like a cup full of sugar crystals with no air between the particles. A normal as rolled or heat treated steel will have grains of approx 0.02 mm in diameter. You need a good microscope to see them.

 

Now heating a steel causes these grains to grow. Any welded steel develops a heat affected zone adjacent to the weld. They could grow as large as 0.2 mm in diameter. The larger the particles are, the weaker the component. And as they say a chain is only as strong as its weakest link = The weld.

 

I now work in the armour industry. Shoot an armour piercing round at armour plate, nothing happens. Shoot the same round at a weld in the plate - Goes straight through.

 

Your problem is - The frame is most likely Mild steel. Mild steel cannot be heat treated to improve strength.

 

Application of heat to the welded area will relieve any welding stresses created and would be beneficial but the strength of the area cannot be improved. This could be as simple as applying a flame torch to the area but temperature must not exceed about 300 degrees.

Edited December 27, 2012 by Firozfx

[Firozfx]

Just realised, the frame could be aluminium. Still does not make a difference to what I said above

[DR ◣◢]

Trust him, he is an engineer.

 

Send the frame to Steve at Morewood if your at all in doubt.

[Cruz Addict]

I am metallurgical engineer. Steel was my thing. Steel is made up of 3 dimensional perfectly fitting grains, like a cup full of sugar crystals with no air between the particles. A normal as rolled or heat treated steel will have grains of approx 0.02 mm in diameter. You need a good microscope to see them.

 

Now heating a steel causes these grains to grow. Any welded steel develops a heat affected zone adjacent to the weld. They could grow as large as 0.2 mm in diameter. The larger the particles are, the weaker the component. And as they say a chain is only as strong as its weakest link = The weld.

 

I now work in the armour industry. Shoot an armour piercing round at armour plate, nothing happens. Shoot the same round at a weld in the plate - Goes straight through.

 

Your problem is - The frame is most likely Mild steel. Mild steel cannot be heat treated to improve strength.

 

Application of heat to the welded area will relieve any welding stresses created and would be beneficial but the strength of the area cannot be improved. This could be as simple as applying a flame torch to the area but temperature must not exceed about 300 degrees.

 

Eish I stand corected, at least I have learnt something new today, thanks Firozfx I feel smarter now!

[DJR]

I am metallurgical engineer. Steel was my thing. Steel is made up of 3 dimensional perfectly fitting grains, like a cup full of sugar crystals with no air between the particles. A normal as rolled or heat treated steel will have grains of approx 0.02 mm in diameter. You need a good microscope to see them.

 

Now heating a steel causes these grains to grow. Any welded steel develops a heat affected zone adjacent to the weld. They could grow as large as 0.2 mm in diameter. The larger the particles are, the weaker the component. And as they say a chain is only as strong as its weakest link = The weld.

 

I now work in the armour industry. Shoot an armour piercing round at armour plate, nothing happens. Shoot the same round at a weld in the plate - Goes straight through.

 

Your problem is - The frame is most likely Mild steel. Mild steel cannot be heat treated to improve strength.

 

Application of heat to the welded area will relieve any welding stresses created and would be beneficial but the strength of the area cannot be improved. This could be as simple as applying a flame torch to the area but temperature must not exceed about 300 degrees.

 

You came to this forum like you were called - we need someone to make us a truly bullet-proof bike - only catch is it must be really really light too - and cheap. Pleas tell us you can do it.

[r.hendrix]

Thanks for all the advice guys. I think in the end I will end up giving Morewood a call just to check, I'm only hoping to get maybe another year out of it so come what may its no train smash, so to speak. A couple more bucks to have it looked at by the pro's will be money well spent.

[DR ◣◢]

With some luck they might have a spare swing arm for you.

[r.hendrix]

That's exactly what I was thinking as well. I've also heard about them selling the older model frames dirt cheap.

[patches]

This sounds like the perfect time to upgrade

 

I cracked my 1st Izimu. 2 months later I bought another. 4 months after that i decided to make the leap to the big Mak

 

 

That's exactly what I was thinking as well. I've also heard about them selling the older model frames dirt cheap.

 

Yup, Sir Maxxis (Mbuzi), Brian Fantana (Shova), Bike Bailing (Izimu), and Peach (Kalula) all got hold of Steve and asked if he had old stock frames/tubing to build a frame, lying around. All ended up with a bargain.

[DR ◣◢]

All are smiling from ear to ear.

[BikeBailing]

All are smiling from ear to ear.

 

Except I am staring at it all the time and waiting for my stuupido shoulder to heal up so I can give the bike it's first run

[DR ◣◢]

How long to go still?