Metal finishing Q&As since 1989

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RUSTING OF 17-4 SS AFTER AUTOCLAVE

17-4 SS, H900, TURNED PARTS, HAVE BEEN LASER MARKED AND NITRIC TYPE 1 PASSIVATE, AFTER 1 AUTOCLAVE CYCLE RUST APPEARS, ALSO LASER MARKING DEGRADES.

DENNIS ONDERCIN
MACHINE SHOP - BROOKPARK, Ohio
2005

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Machined, passivated 17-4 SHOULD be resistant to corrosion from hot humidity. So, two questions-

1. What's in the autoclave? Anything more potent than mere water vapor? What temperature?

2. Is the part made from a casting or forging, and if so, is the rusting occurring on the unmachined surface?

Lee Gearhart
metallurgist - E. Aurora, New York
2005

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You should not be getting any rusting on these instruments if properly passivated. Rusting is quite common in the laser mark area if not properly passivated. You can do this quite successfully with citric acid formulations on the market without removing the mark.

As Lee intimates, you can have lots of problems if it is cast or forged parts. This can be eliminated, also, if treated with the right products and process. I can't mention the products here on this site, but you can contact me if you would like more information.

Lee Kremer
Stellar Solutions, Inc.

McHenry, Illinois

2005