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  • 1.  Corrosion resistance of 300 series austenitic steel vs. 400 series martensitic steel

    Posted 11-28-2021 19:12
    A supplier mistakenly used 400 series martensitic steel instead of 300 series austenitic. 
    We all know that 300 series due to its higher chrome content is a true stainless steel and more corrosion resistant than 400 series.  I have found many online sources which reinforce this 
    What I have not found is any data showing any corrosion/salt spray testing comparing 300 to 400 series. Does anyone have any corrosion/salt spray  test data comparing 300 to 400 series? 
    If possible please also respond to the email carpinz@hotmail.com

    Thanks for any support! 



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    William Pinzon
    BAE Systems
    Greenlawn NY
    (516) 735-5413
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  • 2.  RE: Corrosion resistance of 300 series austenitic steel vs. 400 series martensitic steel

    Long Island Chptr Admin
    Posted 11-29-2021 01:43
    Bill-
    You are looking for "pitting resistance
    equivalent number" (PREN).  I shall send
    some info in the daytime.
    -Jim




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  • 3.  RE: Corrosion resistance of 300 series austenitic steel vs. 400 series martensitic steel

    Posted 11-29-2021 02:10

    I found a link that compares lower and higher Cr content (below), but it's more complicated than that.  I don't think PREN is really relevant because it only applies to austenitic stainless steels, and even then only in ferric chloride.  300 series does generally have better corrosion resistance than 400, but it depends on the environment and loading conditions you're working with, and what failure modes you expect.  For example, if you're worried about contamination in a chemical plant, 300 series is probably better, while if you're worried about stress corrosion cracking in a higher stress environment, you'd want to go with 400 series (or super-austenitic, duplex, etc.).

    https://www.worldstainless.org/Files/issf/non-image-files/PDF/ISSF_The_salt_spray_test_and_its_use_in_ranking_stainless_steels.pdf



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    David Sapiro
    Senior Structural Materials Engineer
    Seattle WA
    dosapiro@gmail.com
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  • 4.  RE: Corrosion resistance of 300 series austenitic steel vs. 400 series martensitic steel

    Posted 11-29-2021 10:20
    First, you can find your answer directly in the ASM Handbook of Corrosion Data (2nd edition) which gives summary compilation for corrosion test results that you will be able to compare directly.

    Corrosion salt resistance is just one aspect of use. Your supplier sent an entirely different material, not just a difference in grade. Whatever application you are using this steel in is intended for austenitic stainless steel, not martensitic. You absolutely should not use this steel under any circumstances and return it to the supplier. Otherwise, you risk liability because of failure due to incorrect material.

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    Aaron Tanzer
    Senior Metallurgical Engineer
    Metallurgical & Materials Technology
    Baton Rouge LA
    (407) 247-9557
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  • 5.  RE: Corrosion resistance of 300 series austenitic steel vs. 400 series martensitic steel

    Posted 11-29-2021 11:28
    I echo what David and Aaron said; this is really apples and oranges, not only with regards to corrosion resistance to particular media but also processing. For example, the way you weld and/or heat treat 300 series is different than how you weld and/or heat treat 400 series. So if you would ordinarily weld this material (I don't see a product form being specified but let's just say it's a pipe) onto a reducer that's also 300 series and solution anneal the assembly, you can't do that anymore because now you have a dissimilar metal weld on your hands and that solution annealing temperature will not be appropriate for the 400 series, nor will you necessarily be able to temper the 400 series like you should since that could sensitize the 300 series. The mechanical properties will be different too of course - for example, your strength is higher but your low temperature toughness will suffer.

    If it were me, unless I were absolutely in a bind where the project schedule couldn't accommodate getting new material and I had no choice but to make the alternate material work, I'd ask the vendor to take it back and give me what I ordered.


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    Sean Piper
    Product / Process Metallurgist
    Ellwood Texas Forge Houston
    Houston TX
    (713) 434-5138
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  • 6.  RE: Corrosion resistance of 300 series austenitic steel vs. 400 series martensitic steel

    Posted 11-29-2021 15:09
    Even in a bind, there is no way this substitution should be used unless there is review and sign-off from a licensed engineer or designer.

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    Aaron Tanzer
    Senior Metallurgical Engineer
    Metallurgical & Materials Technology
    Baton Rouge LA
    (407) 247-9557
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  • 7.  RE: Corrosion resistance of 300 series austenitic steel vs. 400 series martensitic steel

    Posted 11-29-2021 16:22
    I'm not a fan of the phrase "true stainless steel" because it's always environment-mediated as to whether something cracks or corrodes.

    That said, the free-to-members ASM Handbook Desk Edition has this paragraph,
    <Corrosion of Wrought Stainless Steels / 383
    M o s t grades o f stainless steel are suitable f o r
    use in industrial a t m o s p h e r e s , a l t h o u g h lower-
    c h r o m i u m grades can be unsuitable for m o r e se-
    verely contaminated atmospheres. A p p l i c a t i o n
    often depends on the appearance required. L o w e r -
    c h r o m i u m grades can fulfill service r e q u i r e m e n t s
    but will tarnish severely. I f a p p e a r a n c e is i m p o r -
    tant, type 430 is the l o w e s t - a l l o y grade that can
    be used, and a higher-alloy grade u s u a l l y is re-
    quired.>
    So it may be that salt-spray specific results aren't done because it's generally recognized that the martensitic grades aren't great for a salt spray environment.  I'm assuming martensitic but since you only said 400 series, it may well be that you have a ferritic.

    Given that you said your supplier sent you the wrong grade, I'd say that you need to re-evaluate that supplier ASAP, and that the parts being the wrong grade are their problem.  What you also need to look at is whether the parts are physically (apart from general corrosion) adequate/correct, as having a martensitic means you're now susceptible to lower toughness especially at low temperatures, you have to know what hardness they supplied, are these parts going to tend to be SCC vulnerable (environment and hardness controlled) and so on.  Ferritics are SCC susceptible in different environments but have even worse toughness issues depending on manufacture.



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  • 8.  RE: Corrosion resistance of 300 series austenitic steel vs. 400 series martensitic steel

    Kansas Chapter Admin
    Posted 12-01-2021 11:18
    From the commercial truck air brake experience, we need 316/ 316L or PH15-7Mo stainless to resist chlorine ion corrosion used in road de-icing chemicals. The extra Mo addition is needed to form the moly oxide, since the passivated chromium oxide layer is not protective enough with chloride based salts exposure.

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    Patrick Mizik
    ASM Chapter Council Secretary & District 11 Rep
    Principal Metallurgical Engineer
    Haldex
    pat.mizik@haldex.com
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