So It was been hard for me to source a356 or a similar high silicon alloy where I live. I have resorted to buying it online which isn't exactly cheap... I do have an abundant supply of 6061-6063 machine cut offs. Has anyone here tried adding silicon to aluminum? Can't seem to find any info on it, found a youtube video of someone doing it and it seemed to be somewhat successful. I know silicon has a pretty high melting point but maybe it would "dissolve in the aluminum like other metals? Also I could reach the melting point of silicon in my furnace but if I had to get that hot it may not be worth using the fuel. Hopefully you guys have some input. Thanks!!!
here is the real way to add Silicon https://www.belmontmetals.com/product/5050-silicon-aluminum/ its expensive, I tried adding pure silicon lump directly to the melt ( Yes I powdered it also) , I dont think any of it got into solution, it definitely did no just dissolve, even in brass, so your just not getting the heat needed 1414C, yes you could get a furnace up to that temp no problem , it's about the middle of the melting range for cast Fe, but it's sort of a head scratcher to me Why? I have the same issue you do, lots of extrusions, little casting alloy, i have gotten good results by mixing half and half, giving about me at least 3% silicon, which gives me good results (little note cast aluminum at 11% is very common, so I maybe closer to 6-7%) really depends on your source for cast aluminum, mine was lawn mower engines refer to this article and note that 4xx.x series aluminum has up to 17% silicon, and that includes cookware, so you might want to try goodwill for some cast aluminum cookware to mix with your extrusions http://www.substech.com/dokuwiki/doku.php?id=cast_aluminum_alloys here of course is the metal Nerds info it is interesting !!! https://www.phase-trans.msm.cam.ac.uk/abstracts/M7-8.html V/r HT1
The patent document linked below points to some answers to our questions. I also have a lot of extruded as well as a good amount of silicon and have been thinking about alloying it. The beginning of the document (0001-0008) goes into some detail about the challenges involved as well as a solution which is way too sciencey for me. The answer for guys like us is probably to mix the extruded with an existing higher silicon alloy as mentioned above. https://patents.google.com/patent/EP0423912B1 Pete
What does the silicon do to the aluminium? I cast a small picture frame recently using metal from damaged Austin Seven parts circa 1930-ish. Even at 750C and left to cook until the crucible was glowing the metal was still thick and didn't run into tight corners well. Would silicon have helped! or were the 90 odd year old parts not suitable?
Found on internet: Aluminium alloys are grouped according to the major alloying elements they contain. The 4XXX group is alloyed with silicon for ease of casting.Silicon is good in metallic alloys used for casting. This is because it increases the fluidity of the melt, reduces the melting temperature, decreases the contraction associated with solidification and is very cheap as a raw material.
Thanks Petee, I did a second casting using modern ZL12 which was much better. It filled all the small areas very well and if it hadn't been important to use old A7 metal, I would have used the second casting.
Okay thanks guys! I'll just mix with the high silicon alloy I have. Which may be a great compromise cause there is advantages to both depending on the casting
My very first lost foam casting was done with scrap 6061 aluminum. I looked at the composition of 356 casting alloy and 6061 and decided it would be a good idea to stir in 7% silicon I bought on Ebay. I was shocked when the casting was perfect!
