6061 T6 brazed - What temper condition I have? Can it be improoved? 1

[makinist]

Hello Guys,

I have two parts machined from 6061-T6. These parts are going to be furnace brazed (close to 600 Celcius process temperature). However, the supplier who will braze the parts has no idea on what mechanical properites the parts will have after brazing, nor he knows how to improve the strength of the brazed parts. After brazing, the parts are cooled slowly. As this is a strength critical application, I would like to know;

- After brazing, should it be assumed that the parts will be in T0 temper?

-If so, should one expect that the joined parts are going to be naturally aged by time, coming to a T1 Temper condition with improved strength? Lets say after 10 weeks?

-Is it good idea to apply an artificial aging at 200 C to the brazed parts (after brazing)?

The questions may look silly but this is what I can grab from internet with little material background. I am looking forward to hear some expert comment.

Thanks
Andrzej

 

[drawoh]

makinist,

600[°]C? You will not have aluminium 6061-T6. 6061-O is more likely. Based on what matweb.com says, you may have a molten puddle.

--
JHG

 

[blacksmith37]

Not a puddle, more like oatmeal; the solidus temperature is 582 C. I think you need a new supplier.

 

[Compositepro]

Brazing of aluminum is usually done with a low melting zinc alloy.

 

[WKTaylor]

I suggest You get a copy of the Aluminum Association ABH-21 Aluminum Brazing Handbook... very informative/educational.

Regards, Wil Taylor

o Trust - But Verify!
o We believe to be true what we prefer to be true. [Unknown]
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation,Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", Homebuiltairplanes.com forum]

 

[makinist]

Thank you for your responses, and apologies that the brazing is actually performed at 580 Celcius per the supplier. The supplier performed many brazing operations in the past. I do not have Aluminum Association ABH-21 Aluminum Brazing Handbook, but I checked the AWS's brazing handbook, and could not find any line referring to the post treatment of 6061 after brazing. So, after I braze the 6061-T6 parts at 580 Celcius (and slowly cooling to the room temperature), am I having a T0 condition with about 55 MPa yield strength per Matweb? And can I treat it to a T1 condition? s it good idea to apply an artificial aging at 200 C to the brazed parts to improve strength?

 

[WKTaylor]

machinist. Aluminum Association deals with heat effects on 6061...

1. Per ABH-21... braze at proposed temperature...

then water quench...

then age to -T42... or -T62

2. Alternate... I would tend to propose an alternative process...

Make parts from '-O' material.

Soak parts at 530C [solution HT temperature]...

Then introduce the braze filler to the assy... and momentarily raise the temp to 550C to complete the braze...

Then water quench the Assy [equivalent to SHT/Q]...

Then naturally age the Assy to -T42...

Then thermally age the Assy [@160C] to -T62 [if desired].

Accomplish hardness & conductivity test of the Assy to validate HT state.

Regards, Wil Taylor

o Trust - But Verify!
o We believe to be true what we prefer to be true. [Unknown]
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation,Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", Homebuiltairplanes.com forum]