Color change in gray cast iron
Color change in gray cast iron
(OP)
I have a large gray cast iron roller that's subject to friction heating (it's internally cooled). In certain areas of the roller, the color of the material has changed from bright silver to a yellowish color to a dark blue.
Obviously it's been heated above some sort of transition temperature but I'm wondering if anybody could give me an estimate of how high. The highest measured temperature is about 125C
I don't know the specific composition of the material.
Obviously it's been heated above some sort of transition temperature but I'm wondering if anybody could give me an estimate of how high. The highest measured temperature is about 125C
I don't know the specific composition of the material.
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RE: Color change in gray cast iron
You have some type stain or a light oxidation due to the enviroment.
What is the enviroment the roller sees?
RE: Color change in gray cast iron
RE: Color change in gray cast iron
Another data point: An earlier roller was apparently statically cast and has not seen the same discoloration while (presumably) seeing the same environment.
Would there be some difference in a statically cast roller vs. a centrifugally cast roller that would account for a different response to the heat?
Also, in order to maintain full strength & toughness, what would be the maximum permissible operating temperature of gray cast iron?
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Bring back the HP-15
www.hp15c.org
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RE: Color change in gray cast iron
At temperatures up to 600 - 700F all types of unalloyed cast irons show little if any decrease in strength. At temperatures above 700F the tensile strength decreases rapidly.