Tech question about Ali welding on handlebars..

[sharky]

Quick question for the likes of Ben etc....

The top of the 'riser' part of the bars I'm making is 30mm x 30mm cross section. I'm looking at welding 34mm/6mm wall tubing to it for the bars. I will round out the top so it's a snug fit with larger weld area.

There is going to be a MX style cross bar between the two 'risers'

Question, .just to set my mind at rest, is this going to be strong enough ?

[latheboy]

How long is a piece of string?
Need to know what grade of Al. you are using to make a good assessment on this.
Make sure there are no gaps before weld as Al. pulls a lot ..
Lots of grades will need to be heat treated after welding.

[sharky]

6061 mate

[Redmohawk]

Welding with 4043 filler will be less likely to crack , welding anealed 6061-T6 will drop it to T0 spec you'll need heat treating to bring it back up to T4 Or T6 spec . 6061-T0 spec is half the tensile strength of T4 .

[sharky]

This stuff is T6

[Redmohawk]

Not once you've welded it , it will revert to T0 (18,000 Psi tensile) once welded for the material around the weld. T4 is 30,000 Psi T6 is 42,000 Psi. The weld will be stronger than the parent metal around the weld, tempering will regain some strength (back to T4 spec)

To get it back to T4 spec you need to EVENLY heat the whole assembly to 530 deg c over about an hour then quench in enough water (that final water temp doesnt go over 35 deg) , you will get some distortion . Ali will remain "soft (T0)" for about 20 min after quenching then will set at T4 . To get it back to T6 from T4 is a whole new ball of wax and not possable without very specific tools heating for a day then cooling over as long back to room temp.

[sharky]

Working on a way to bolt it together lol

[Redmohawk]

Just an Idea ,Press a turned bit of Ali into the bars from eather end down to where your needing to bolt to the upright's to make anti crush sections, then use High tensile bolts with allen head drive countersunk heads. Top off with some ali tube cut/shaped to make covers for holes over the top of bolt heads with 6mm round N52 grade rear earth magnets glued to the back that fit into Allen head hole. To give you a Bars fixed without bolts effect ? Easy to remove for access and if you polish or anodise should look clean.

[latheboy]

Countersunk cap screws, not Allen head

[Redmohawk]

Yeah , brain fart

[safighter]

cap screws are allen key heads yes , I was going to weld risers on mine until i realised that you cant really tell what ally they made the top yoke out of so its hard to determin the best way to keep tensile strength up,machine and bolt .

[kiwi kdx]

Here's a mint job............!
http://i248.photobucket.com/albums/gg173/d21terrano/20130525_083818_zps7f1bad9e.jpg