Casting alloysA356 vs 6063

[t28flyer]

Hello To All

We recently had some cylinder heads sandcast that was supposed to be A356 alloy. While inspecting some other castings with a touch Spectrometer we discovered that the casting house has used 6063 instead.
How screwed are we? We have roughly 1000 hours of machine work in 4 heads

Thank You
Rod

 

[mw1st]

A356 alloy has much higher Si content then 6063, so has better fluidity, easier to cast, feed, it's harder, stronger then 6063 but lower ductility. Somewat harder to machine. The properties will vary with heat treatment.
A 356 is a good alloy for thin section, leak tight castings. It also provides
good corrosion resistance. End uses include cylinder heads, blocks and wheels. 6063 alloy, is not generally use for cylinder heads. Design engineer selected 356 alloy for a reason. I would ask the foundry, why your parts got casted in incorrect alloy? Something must have gone wrong. The heat went out of control.. lol. Also, your customer may not be to happy about the whole situation. Having said that, you may be screwed.
I'm attatching a file, so you can review/compare properties and applications these two alloys.

 

[swall]

I would double check the analysis. It makes no sense to cast AA 6063, as it is not a casting alloy.

 

[metengr]

I would agree with swall. Have a small sample removed for a proper chemical analysis. Was the surface prepared properly for PMI?

 

[t28flyer]

We checked the part with a XRF scanner. The case it came in was the gold unit. unfortunately who ever put the unit in its case put a base model in the box.
It will not read silicon content. So the scan defaulted to the nearest material. We sent a sample to a certified lab and it came back as A356
Thank You for your time

 

[swall]

Yes, the truth is out there.