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topic 32786

Prevention of White Rust in Aluminum Castings

A discussion started in 2004 but continuing through 2018

(2004)

Q. Good morning sir,

I am hemavathy, working as an executive in a die casting division which produces aluminium castings for automobiles and we have white rust formation in our castings. Our castings are stored properly and are safely packed in polythene covers. Could anyone please suggest me some useful ways to save the castings from the white rust.

With regards

G.D.Hemavathy Durairaj
- Chennai, Tamil Nadu, India


Humidity Control Design Guide
from Abe Books

or

(2004)

A. Hi. They perhaps are not chromate conversion coated or phosphatized; they should be. Plus, you need to keep them dry. Good luck.

Ted Mooney, finishing.com Teds signature
Ted Mooney, P.E.
finishing.com
Pine Beach, New Jersey


(2005)

A. Over the years I have experienced oxidation or white rust on aluminum castings after machining and washing them. Flare ups were usually in late summer (July, Aug) and in late winter (Feb, March). The primary culprit was humidity. Not many are aware that the late winter months are quite humid. The most effective way of dealing with these flare ups was to start using DI water for any operations ie. coolant mixing , washer recharge, etc. I am certainly not any type of expert, but the premise of DI was to eliminate or greatly reduce the chlorine content of any mixture coming in contact with the aluminum. It was not 100%, but it made a dramatic improvement.

Good Luck!

Pete Brown
- Petoskey, Michigan


October 8, 2009

A. Use alloy 360, has low copper, which has low potential for white corrosion.
Do not allow humidity in your parts, before storage.

A drop of water will be a spot of white corrosion.

Fernando Damasceno
- Sanford, North Carolina


January 28, 2010

A. VCI bags and VCI sheets can be used for packing and after machining. Running DM water can be used for washing.

Abdul Kadhar
- Chennai, Tamil Nadu, India


May 7, 2015

A. White rust forms on the surface of aluminum as a result of corrosion(actually oxidation). Chromation will be a better surface finish to prevent corrosion.

Anissh Jayaraj
Product design - Chennai,Tamil nadu, India



March 17, 2018

Q. I experience white rust during production of aluminum strip from the cold mill. What might be the cause of this? It's giving me so much concern, at first I thought the rolls were bad and caused friction with the strip but that doesn't seem to help too. Please advise.

Joseph ogochukwu
Caster and mill Engr - Enugu, Nigeria



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