ASM Online Member Community

  • 1.  Hardness conversion for austenitic stainless steels

    Posted 11-06-2021 16:39
    Would table 3 be appropriate for conversion of austenitic stainless steel hardness conversion?

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  • 2.  RE: Hardness conversion for austenitic stainless steels

    Posted 30 days ago
    Sorry, forgot to say ASTM E140

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    Lawrence Cheung
    Sr. Principal Metallurgist
    Northrop Grumman
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  • 3.  RE: Hardness conversion for austenitic stainless steels

    FASM
    Posted 30 days ago
    E140, Table 6 is intended for austenitic stainless steels.

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    John Grubb
    New Kensington PA
    (724) 448-5272
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  • 4.  RE: Hardness conversion for austenitic stainless steels

    Posted 30 days ago
    Yes, thank you, but I was looking at a way to convert microhardness to Rockwell hardness.

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  • 5.  RE: Hardness conversion for austenitic stainless steels

    Posted 27 days ago
    No valid conversions are available for austenitic steels, though many have asked. I am aware of some companies that approved use of the nickel conversions in Table 3 for their internal use, but none have said so publicly.

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    Aaron Tanzer
    Senior Metallurgical Engineer
    Metallurgical & Materials Technology
    Baton Rouge LA
    (407) 247-9557
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  • 6.  RE: Hardness conversion for austenitic stainless steels

    Posted 26 days ago
    This sounds like an opportunity to "do it yourself".  Send a collection of relevant parts to a lab and have both tests done.

    I used conversion tables extensively and learned that they have their limitations.  What are the error bands and uncertainties?  Very few conversion charts have this information available, even if the originators did a good job of collecting it.

    How well were the machines calibrated?  Manual or automatic application?  Then you get into the materials issues: has any cold work been done?  How does the hardness vary with depth of cold work?  (Substantially for austentics.)  Is the test being done on a cross section or an original surface?  What surface prep was involved, a metallographic finish for the microhardness versus as-rolled or rough ground for Rockwell?

    If you commission your own test you can control all of this, though you may be dismayed at the variability of the real world compared to a nice single value in a handbook conversion table.  However the cost of getting it wrong may exceed the cost of testing.  Establishing a correlation within a limited range of hardnesses and product forms may pay off for you, or you may learn that the conversion value should not be relied upon.

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    Paul Tibbals
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