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Salt Spray Test on Stainless Steel SUS303 and SUS304

2006

Can passivated SUS303 & SUS304 parts withstand 48 hrs salt spray test without rust ?
In the first place, should we subject these austenitic type of steel to 48 hrs salt spray test ?

Any advise / method to ensure SUS303 turning part withstands 48hrs salt spray test, ASTM B117, without rust

Thanks.

YK Wong
- Malaysia

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304ss will normally withstand 48 hr. of salt spray with no problem if correctly passivated first.
303ss can be a real problem if not properly treated. You must remove the sulfides from the surface or you will get yellow/orange stains and beads that look like rust on the surface during the salt spray test. Assuming good passivation prior to test, these will probably be sulfides on the surface coming out of the intergranular boundaries. Treatment with hot NaOH solution before and after passivation will prevent this.
Contact us if you need help.

Lee Kremer
Stellar Solutions, Inc.

McHenry, Illinois

2006

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December 3, 2010

We need to test in NSS a strip of s.s. AISI 430 grade (0.5 mm thick). Is it correct to assess the evaluation after ISO 10289 and the preparation after ISO 9227?
I know that salt spray test refers more to the coated and painted material! Is there another standard guide for testing the strip and plate of stainless steel -- especially ferritic?
Thank you very much.

Petre Camelia
- Romania

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Petre: There are other tests in ASTM A967 which can be used for determining whether the passivation is acceptable. For ferritic grades of steel many companies use the boiling distilled water test. It is simple and easy to run without purchasing equipment. You can purchase the ASTM standard at ASTM. If you would like us to email you similar tests, you can contact us and we will send you digital copies. We cannot give you a copy of the ASTM standard.

Lee Kremer
Stellar Solutions, Inc.

McHenry, Illinois

December 3, 2010