Grey and Ductile Iron Machine (Increased Tool Life) Better With Age. Why? 1

[allen2929]

Metallurgy and Materials Engineering Community:

I have a question that I have asked countless Metallurgical and Materials Professionals over the past 10 years
without a good answer. I work in a foundry that makes gray and ductile iron parts for the automotive industry.
Once the parts are produced, they are machined to customer's specifications.

We have studies that show that if we age the castings (allow it to sit for 90 days or more) before we machine it,
tooling life triples verses machining the castings immediately after production. The microstructure (100x) for
the green verses aged iron appears to be the same as well as all mechnical properties.

I have asked this question of professionals that have been in the field for 40 plus years without a scientific
reason. Now I ask the Eng-Tips Community. Please advise...


Allen
10-14-12

 

[TomDOT]

DOE-funded research paper on the subject:

http://www.osti.gov/bridge/servlets/purl/812004-hqPv8q/native/812004.pdf

 

[btrueblood]

Great link, thanks Tom.