I bought several barrels of Strontium and TiBor at a foundry close out auction (sadly it was the place I used to work).
I am offering it in small lots to help out hobby casters.
I have it for sale on eBay , since I want to create an account.
I want to keep the price low so everyone who needs it can get some, unfortunately I can’t create a Buy It Now price until I have enough feedback. I intend to list it for $5.00 plus shipping once I can, so don’t bid too high, I will keep setting up new auctions until eBay lets me set a Buy it Now price.
What is a Modifier, What Does it Do, Why do I Need it?
Typical foundry Aluminum casting alloys (engine blocks, heads, transmission cases, pistons, wheels, other cast scrap) contain 5 to 12% Silicon.
Unmodified castings made from these alloys contain coarse, plate-like crystals of Silicon which forms during solidification (eutectic Silicon). These Silicon particles are in the form of brittle needles which reduce the strength and ductility of the casting. They also tend to create porosity by inhibiting the flow of molten metal (feeding) in to areas of the casting as it solidifies.
With Strontium modification, a different and improved cast structure is developed in which the Silicon phase is “modified” by the action of Strontium to become fibrous and finely dispersed. The result is improved mechanical properties. In particular, both ductility and machinability are improved.
Strontium also tends to reduce the size and shape of harmful iron compounds, resulting in improved ductility. It can reduce the embrittling effect of Iron contamination if you melt/pour with a steel ladle.
Modification has been called “the poor mans heat treatment”, since it improves as cast strength without the need for heat treatment.
Please note that if you are melting low Silicon alloys (Aluminum cans, siding, ladders or extrusions) this Strontium modifier will not make any improvement since there is little Silicon to modify. These materials are not designed to be cast, and you may want to consider changing to an alloy designed to be cast to improve your casting success.
What is a Grain Refiner, What Does it Do, and Why do I Need It?
When metals solidify they develop a grain structure. Slowly cooled metals (for example from sand casting) have a relatively large grain size. Faster cooled metals (for example from die casting) have a smaller grain size. Benefits from a smaller grain size include; better feeding for reduced shrink porosity and stronger castings.
A grain refiner promotes a smaller grain size even in a slow cooled casting.
Here is a good practical publication that explains this in a bit more detail.
How to Use
As per manufacturers recommendations add 3 rods per 100 pounds (or 1 rod per 33.3 pounds).
With a few rare exceptions, it would be hard to overdo it, so just add 1 rod of each if you are melting less that 30 pounds per melt.
With a small melt, add both the TiBor and Strontium rods as soon as all the metal has melted, and gently stir, skim and pour.