356 aluminium sand casting elongation values 10

[Nadimuthu]

We have cast equivalent alloy to 356 Aluminium in sand casting ie AlSi7Mg.Its specified elongation value is 2%in fully heat treated condition(T6).But the value of elongation required for 356 is 3% which we are not getting.
The test bars are as per Foseco foundryman handbook specification chemical melt treatment was done using Foseco chemicals as per their recommendation.Heat treatment cycle was 535-540c with quench in hot water(65-100c)both inclusive in 12 hours.Cooled to Room temperature and then Precipitation hardened at 140c for 6 hours.
Please offer your advice on the procedure to be followed to achieve this elongation in 356.

 

[alucast]

Hi etch!
Sorry forgot to tell u that we are based in Poland.I dont think that we are in competition.We dont do any aerospace at all.We focus on large sand castings 50kg-500kg.We supply many different industries like medical,mechanical,electrical,lighting....
So nothing to hide I guess.
What do u think about the suppliers of the furane?
I think there was a misunderstanding regarding density.We usually have density of 2,6g/cm3.
Do u coat the moulds of the test bars?

 

[etch]

The suppliers of furane seem fine we use the same.

as for density, how are you measuring the figure?

We use a sine machine and it basically measures two samples one solidified under air one under vaccum, then you take the two figures and weight them in and out of water , and this gives you a density index figure.

Yes we coat the moulds of the test bar.

If you would like give me your email address and i will send you a drawing of sand casting, test bar moulds drawings.

 

[alucast]

Thanks a lot for your help etch!
Our e-mail: alutec@pro.onet.pl
I post you my results as soon as i get them.

 

[fly18]

Hello,
I am working in a Research and Development Center, in the Light Alloys Department. At this moment we are interested in AlSi7Mg alloy and I would like to know if there is any investigation in how porosity affects elongation.
I would be very pleasent if anyone could tell me in what publications I could find something interesting.

Thanks in advance.
Kind regards.

 

[TVP]

fly18,

The following links should be useful to you:

http://www.sciencedirect.com/scienc...md5=9db3c1ee11251782c11017325f3b0c2f&ie=f.pdf

http://www.mse.eng.ohio-state.edu/~mobley/diecasting/CHARACTERIZATION/references/references.HTML

Gas Porosity in Aluminum Casting

http://www.afsinc.org/estore/srch_Detail.asp?OrderNum=NF0103

Design and Product Optimization for Cast Light Metals

http://www.afsinc.org/estore/srch_Detail.asp?OrderNum=RR0006

Aluminum Casting Technology, 2nd Edition

http://www.afsinc.org/estore/srch_Detail.asp?OrderNum=NF9300

ASM HANDBOOK Volume 2

http://www.asminternational.org/Tem...=Ecommerce/ProductDisplay.cfm&ProductID=10433

ASM HANDBOOK Volume 15

http://www.asminternational.org/Tem...=Ecommerce/ProductDisplay.cfm&ProductID=10490

 

[etch]

Alucast,

I have sent you some emails regarding tensile tests.

 

[fly18]

TVP,

Thanks for the links, we have some of them but there are no many information about our problem.
I have seen relationship between mechanical propierties and DAS, but no with porosity althoug it is always mentioned. I mean I have found mechanical propierties vs DAS representation for differents heat treatments but no representation of mechanical propierties vs porosity.
That is in what I am interested on.
Do you know something about it??

Thanks.

 

[alucast]

What temperature should i cast the test bars at?

 

[etch]

For horizontal test bars the temperatures should be 700oCto 710oC and preferably, the mould should be warmed before use by pouring and discarding the first casting. the metal should be poured more quickly into chill moulds than sand mould, filling the mould i a few seconds while taking care to avoid turbulance. and keeping the top of the ladle as near the mould as possible.

For sand mould the mould should be tilted to 45 degrees and the metal poured in a very thin stream. Bars should be left for at least 20 minutes.