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Superchilling/cooling castings and metals

Superchilling/cooling castings and metals

(OP)
Hi Everyone!

First time I've posted here, but I'm struggling to find any information regarding the supercooling (also known as superchilling)of metals and castings, particularly the effect on the materials grain structure and how it affects it mechanical properties. I've tried looking looking on the internet and in various books but there seems to be no information on the subject.

I would appreciate any information or help with this, cheers!

RE: Superchilling/cooling castings and metals

Perhaps using the term subcooling will help.
There is a lot of work out there regarding the impact of accelerating the cooling rate of castings.
We used to use cast iron chills in molds to get preferential cooling patterns in high Cr white cast iron.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

RE: Superchilling/cooling castings and metals

There is quite a lot of information on the internet for "cryogenic treatment" of metal. My guess is this is what you may be looking for versus adding chills to a casting mold to locally expedite cooling of the casting. You will find a wide variety of opinions on the benefits of doing cryogenic treatment for austenitic stainless steels.

RE: Superchilling/cooling castings and metals

2
There is a HUGE amount of really spectacular BS available on the subject of Deep Cryogenic Treatment (DCT) of metals.

Clearly there are some applications where there are explicable and significant benefits to be obtained by using DCT but unhappily the industry seems to be populated by a large number of 'Snake Oil' salesmen who make preposterous claims that will never be substantiated.

It is clear that DCT an be beneficial in eliminating problems in tool steels caused by residual austenite and that in some cases can cause the precipitation of eta carbides but may of the claims beyond this seem to me to be pure BS,

Many of the claims made just don't stand up to any sensible asnalysis and few if any results are ever published.

Good Luck.

RE: Superchilling/cooling castings and metals

Dr. Randall Barron of Louisiana Tech Is generally credited as the scientific authority who ”proved the value of cryogenics”.

I have read some of his work. It has been a while but, as I recall, he was paid to run some tests for a cryogenics company. His results stated that sometimes something happened. I remember being impressed by his science and rather appalled at how it was represented by the cryogenics people.

Thomas J. Walz
Carbide Processors, Inc.
www.carbideprocessors.com

Good engineering starts with a Grainger Catalog.

RE: Superchilling/cooling castings and metals

2
The topic of supercooling on the solidification characteristics of metals and alloys is discussed in Chapter 5 of my book Metallurgy for the Non-Metallurgist, second edition. It looks like you are in the United Kingdom. The book can be found on the library shelves of the following universities in your country:

http://www.worldcat.org/title/metallurgy-for-the-n...

Maui

RE: Superchilling/cooling castings and metals

Maui,

That post was worth a star, just for the link to worldcat.org. Thanks!

RE: Superchilling/cooling castings and metals

(OP)
Just to let everyone know I passed the assignment on super cooling, and thanks to everyone for giving me advice how little or large! It seems its quite a large topic, but very little is known about it at the level I'm studying at.

Cheers Maui, I've had a quick look at that book and it looks right up my street!

Thanks again to everyone, greatly appreciated!

RE: Superchilling/cooling castings and metals

Research on Deep Cryogenic Treatment (DCT)of materials in general is available at http://www.cryogenictreatmentdatabase.org/. This is site set up by the Cryogenic Society of America. I also suggest that you look in Volume 4A of ASM Handbook. There is an article there that differentiates between cold treatment and DCT. Read the research.

DCT has been shown to create substantial increases in wear resistance and fatigue life in many metals, carbide tooling and in some plastics. Again, read the research. Yes, it can convert retained austenite to martensite and in some steels it does cause small carbides to precipitate. We are finding that it is also making changes in the crystal lattice structure. This is why it has an affect on non ferrous metals and carbides. This has confused many metallurgists who only look at grain structure. The idea that the austenite/martensite shift is the only thing happening ought to look at the huge increase in the life of cast iron brake rotors that are treated. They have a pearlitic micro-structure that has no retained austenite.

DCT has many uses in industry. Yes, many wild claims have been made about it. But many claims that sound wild are true. Those "doubters" who dismiss DCT without reading the research should be ashamed to call themselves engineers and scientists.
Again, read the research.

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