Replacement for Nickel Cast Iron 5

[furnacegal]

Our company has a component (Bearing Casting) that is currently specified as a Nickel Cast Iron or an ASTM A-48-55 Class 30 Cast Iron. The specification dates back to 1963.

With the rising cost of Nickel we need to find a more economical solution, however standard Gray Iron presents pin hole issues. Can anyone recommend an alternate material that has low porosity and similar mechanical properties without using Nickel as an alloying agent?

Any advice would be helpful. Thanks!

 

[swall]

You need to properly identify the problem before you put a fix in place. You should not have a chronic pin hole problem with good quality class 30 iron castings. What is the nickel content of the iron and why was that material chosen?

 

[furnacegal]

the nickel content is around 3%. I am still investigaing on our end but from what I have been told when they cast with nickel the parts come out fine, when they remove the nickel they only get 1 in 5 good parts. The bigger issue is the cost of nickel and if there are any alternatives for the casting other than standard cast iron.

 

[arunmrao]

furnacegal, it does not clarify swall's concern regarding the problem lying else where. Why did you need a Nickel addition to improve high temperature properties? But this has nothing to do with pin holing problem. In case you provide more details,like melting techniques,mold and core materials,weight of castings,metal treatment etc, you will get several good responses from this forum.

_____________________________________
"It's better to die standing than live your whole life on the knees" by Peter Mayle in his book A Good Year

 

[salmon2]

3% Ni is not much, I doubt getting rid of Ni will save you much unless your tonage is huge. Ni price is what? $15/lb right now?

 

[EdStainless]

Ni is under $9/lb now, so about $0.30/lb of casting.
the Ni isn't the magic for making good castings. Your foundry has some serious moisture/hydrogen/oxygen issues that they need to address.
A Ni addition does increase the toughness (esp at low temp) and hot strength of the metal.
So we ask again, why was this alloy specified?

= = = = = = = = = = = = = = = = = = = =
Plymouth Tube

 

[salmon2]

0.30/lb is big, I didnot do the math.

 

[arunmrao]

Nickel is an expensive addition for a cast iron. The problem has severe problems in the molds or cores causing pin holes. But, I am unable to understand how does the addition of Nickel,reduce these issues?

_____________________________________
"It's better to die standing than live your whole life on the knees" by Peter Mayle in his book A Good Year

 

[sreid]

Porous castings can be polymer impregnated but there is a cost to doing that too.

 

[EdStainless]

The Ni and the porosity are just coincidental.
The Ni isn't giving better castings, a change in melting/casting practice is giving the bad ones.
These are two separate issues.

= = = = = = = = = = = = = = = = = = = =
Plymouth Tube