How to identify which aluminium and filler wire to use for a project 2

[Voodooman]

Hello this is my first post so hope some one can help
Fist we'll start with the project which is my honda cr500 af
Explanation cr is Hondas two stoke motocross bike and AF stands for alloy frame
Now honda never produced an alloy framed two stroke with 500cc
But people have been building hybrid 500 bikes for some time
These bikes are known as the bike honda should have made
So that the explanation why
Now a little of my back round
I have a health back round of liking to do things correctly with my own hands to a high standard I work in automotive industry preparing circuit cars
Now down to business
The problems with these frames if they have problems is to fit engine you have to cut frame and make a new y piece then weld into the frame if its not correct it cracks as you would expect if you now about alloys and the high frequency of a two stroke engine
I have had a piece of the frame tested and from that I think it is a t6 7xxx alloy but I can't work out the rest can some one help
Here's the test results
Si 0.050-Mn 0.21-Cr 0.018-Cu 0.13-Fe 0.13-Mg 1.49-Ti 0.009-Zn 5.41-Zr 0.19
High zinc means 7xxx ? If I'm doing this correctly I have to identify material then from that a filler rod then finally the correct heat treatment to bring it all back to full strength can anyone help ?

 

[gtaw]

Aluminum; "Almost a Metal"

Aluminum has poor fatigue properties and depending on the particular alloy, good to poor weldability. The 7XXX alloys have a range of weldability, but none are easily welded because of the zinc used as an alloying constituent. If the frame is already welded, it is clearly on of the weldable alloys.

You could visit a few of the electrode manufacturer's websites to see if they have any suggestions as to which of their filler metals is best for your application.

Best regards - Al

 

[Voodooman]

Frame is welded it is castings and extrusions
People say 7xxx alloy is hard to weld but
These frames are welded all the time and most are ok
But no one knows .they are just doing it blind.
Most likely using 6082 to make the y piece and using
5052 filler and not heat treating frame back to
Full strength
I thought if I had it tested it would be easy
I should have known .I expected the test result would come
back as 6062 or 7075 etc I think I am going to
Pick the most weld able 7xxx and then try and find a supplier
That deals in filler wire but I still would like to know what grade
this frame is

 

[CoryPad]

Using the Aluminum Association Teal Sheets, your part composition matches alloy 7018.

Alcotec has a nice filler wire selection chart:

http://www.alcotec.com/us/en/support/Alloy-Selection-Chart.cfm

Assuming alloy 7018 welds are similar to alloy 7005, the Alcotec chart shows the suitable filler wire choices to be 5183, 5356 or 5556.

 

[Voodooman]

That's the answer .thank you so much I can now look
for the materials .I feel like I just won the lotto
and its good knowing those magic numbers

 

[tbuelna]

Voodooman,

You stated that your frame is composed of aluminum castings & extrusions. It is unlikely that the castings and extrusions are the same alloy, so if you are welding a joint between a casting and an extrusion it may factor into your choice of welding wire. It seems like CoryPad has answered your question as to what alloy the extrusion is made from (7018), but this alloy is not suitable for casting. In order to determine the alloy used for the castings, it would be helpful if you could first determine what form of castings they are- sand or permanent mold. As a general rule, if the casting has any internal hollow sections then it is likely a sand casting, and if not then it is likely a permanent mold casting.

If you also refer to the chart linked by CoryPad, assuming that the extrusion is similar to alloy 7005 then there are only a few casting alloys ( ie. those listed in the left side box of the top two rows of the chart) that provide a suitable match for fusion welding to 7005. So by process of elimination this would narrow down your choice of filler wire alloy.

After you determine what type of casting (sand or permanent mold) you are welding the extrusion to, you may be able to narrow your choice of filler wire further by eliminating any alloys listed in the chart that are not suitable for the type of casting you have. You can find numerous references online that list which aluminum alloys are suitable for specific casting processes.

Hope that helps.
Terry