ASM Online Member Community

Expand all | Collapse all

Martensite in Steel

  • 1.  Martensite in Steel

    Posted 03-08-2021 11:14
    What is the correct way to call Martensite in steel? Is it un-tempered Martensite? Or martensite only?
    I have limited years of experience in steel alloys processing, but never came across the term, "un tempered martensite" for martensite microstructure,  unless there is presence of  residual martensite in tempered martensite microstructure. Please advice.

    Sanjay Kulkarni

    Materials Engineer

    MSSC

    a group company of MITSUBISHI STEEL MFG. CO., LTD.

     




    ------------------------------
    Sanjay Kulkarni
    Materials Engineer
    MSSC
    Troy, MI
    248-840-1056
    ------------------------------
    Journal of the Month


  • 2.  RE: Martensite in Steel

    Posted 03-09-2021 01:10
    Hi Sanjay,

    Great question! Untempered martensite is what you get just after quenching. It leaves a very needle-like microstructure that's very hard but also quite brittle. Tempering is then performed at much lower temperatures to make the microstructure more homogenous, shorter, and then also much more ductile. The Charpy impact toughness rises substantially and the strength decreases by quite a bit. In some cases, like knives, swords, and blades, the harder material is better so no quenching is used. Conversely, in most engineering applications you need some toughness (aka the resistance to growth of a crack), so the tradeoff of a moderate reduction in strength is worth it. Summing up:

    Tempered martensite has been heat treated to make it slightly softer but much more ductile (and tougher).
    Untempered martensite is fresh out of quenching, very hard but not very tough.

    Best regards!

    ------------------------------
    Joshua Jackson
    CEO
    US Corrosion Services LLC
    Houston TX
    ------------------------------

    Journal of the Month


  • 3.  RE: Martensite in Steel

    Posted 03-09-2021 08:44
    Hi Joshua,
    Thanks for quick response, so the question remains is should I call it un-tempered martensite or just martensite in the report. As far as I know as per metallurgy both types are martensite since they are not tempered. Which is the most appropriate to address in reports martensite or un- tempered martensite for as quenched microstructures?
    Regards,

    ------------------------------
    Sanjay Kulkarni
    Materials Engineer
    MSSC
    Troy, MI
    248-840-1056
    ------------------------------

    Journal of the Month


  • 4.  RE: Martensite in Steel

    Posted 03-09-2021 08:54
    Usualyy, for as-quenced microstructure I use "untemperd martensite" or "tetragonal martensite".
    Regards,

    ------------------------------
    Andrea Talamini Minotto
    Villorba Treviso
    ------------------------------

    Journal of the Month


  • 5.  RE: Martensite in Steel

    Posted 03-10-2021 10:00