Hi guys spent. Most of yesterday modifying the frame to take a 750 engine. Talking to a friend at work today and he said I'd have to get the frame re-hardened after all the fabrication! So a few questions where they hardened when they where made? Anyone know where I can get the process done? Has anyone welded a frame and it's been fine after? Is my mate talking crap? I'll await your replies Phil

you are talking about heat treatment and it is probably that you need to redo it after welding - it makes the metal brittle and so you heat treat to de stress it.

Local fabrication or alloy company will hook you up a few hours in the oven!

what kind of temperature are we talking?

2xxx, 6xxx, & 7xxx series aluminum alloys are Precipitation hardened alloys. (These are used for High-strength / low-weight appplications.) To properly return the alloy (POST WELD) to its original (high strength) molecular phase, you MUST "resoluntinionize" the metal. This entails: 1.) heat the metal to it's austenization temperature 2.) Quench the metal faster than its critical-cooling-rate 3.) Age the material. This is usually done artifically and at a max temp for a specific amount of time.

It's the AGING that gives the aluminum it's Strength. NOT the quenching.

^^copy and paste job - suspect the frames are 6061-T6 alloy and so have a goosey gander for that on tinterwebz - it is more involved than pointing a hair dryer at it...

CMSMJ1 wrote:2xxx, 6xxx, & 7xxx series aluminum alloys are Precipitation hardened alloys. (These are used for High-strength / low-weight appplications.) To properly return the alloy (POST WELD) to its original (high strength) molecular phase, you MUST "resoluntinionize" the metal. This entails: 1.) heat the metal to it's austenization temperature 2.) Quench the metal faster than its critical-cooling-rate 3.) Age the material. This is usually done artifically and at a max temp for a specific amount of time.

It's the AGING that gives the aluminum it's Strength. NOT the quenching.

^^copy and paste job - suspect the frames are 6061-T6 alloy and so have a goosey gander for that on tinterwebz - it is more involved than pointing a hair dryer at it...

From the same thread for more detail: http://www.eastoncycling.com/bike/wp-co ... 5_6061.pdf

I doubt you will need to h/t the frame after welding. Chances are its 7003 or 7005 which is easily weldable. Often used in extrusions (which the main spars are) bike frames etc.

Very fancy frames might be more exotic alloys but mass production bikes are made to be cheap. Not so long ago Suzuki gsxr1000 had a frame recall for cracking around the headstock under abuse loads and the solution was to weld in a strengthening brace at the dealer - no chance the frame was heat treated after that

I have welded loads of frames without heat treatment and never had a problem,if I recall frames are 6000 series.

Correction on the suzuki recall, the brace wasnt welded in.
Also
http://papers.sae.org/2001-01-1884/

cheers guys thanks for the info