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Impact of additive manufacturing

  • 1.  Impact of additive manufacturing

    Posted 03-06-2022 09:36

    What do you see happening in additive manufacturing of metallic components, and what impact do you think that will have on traditional heat treating in the next five years?



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    Stephen Maus
    Partner
    MetalPro Resources LLC
    Greenwood IN
    3174057047
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    Data Ecosystem - Global Materials Platform


  • 2.  RE: Impact of additive manufacturing

    Posted 03-07-2022 02:06
    AM is like any other buzz word in materials science: there are claims that it will solve all of our problems, then it dies down and becomes a minor part of manufacturing.  Particularly in the context of heat treating, I don't expect metal AM to play a large role in manufacturing over the next 5 years.  The biggest impact would probably be that parts are more likely to be heat treated after manufacturing (normalizing and stress relieving) which is not always necessary after machining.

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    David Sapiro
    Senior Materials Engineer
    Seattle WA
    dosapiro@gmail.com
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    Data Ecosystem - Global Materials Platform


  • 3.  RE: Impact of additive manufacturing

    Posted 03-07-2022 06:34
    I don't see any impact on HT at this time

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    Marin Manole
    Foundry Metallurgist
    SP FOUNDRY
    Coffeyville KS
    (616) 227-1668
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    Data Ecosystem - Global Materials Platform


  • 4.  RE: Impact of additive manufacturing

    Posted 03-08-2022 07:36
    Edited by Colin Fletcher 03-08-2022 07:37
    Most additive companies seem to be using standard, or close to standard, heat treatments for 3D printed alloys at this time. There has been a little churn on that front in the industry, and a few companies and researchers are coming to the realization that heat treatments may need to be tailored specifically to 3D printed materials just as they are for other product forms.

    I do not expect additive manufacturing to drastically affect heat treatment, but I would guess more additive-specific heat treatments will appear in industry specifications as they're developed, and there may be a renewed emphasis on low-distortion quenching & heat treating methods to deal with the net and near-net shapes as the technology is gradually adopted. 


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    Colin Fletcher, PE, CWI
    Sr. Metallurgist
    Xerox R&D / 3D Printing
    Cary NC
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    Data Ecosystem - Global Materials Platform


  • 5.  RE: Impact of additive manufacturing

    Posted 03-08-2022 09:09
    As with most new technologies, the materials research and documentary standards often lag the 'wave' by a considerable period, and this is the case with AM.  The microstuctures and properties are substantially different from what we see in wrought/cast materials with the same composition.  That means the heat treatments designed for wrought/cast do not apply to AM.  One needs to consider AM as 'new alloys' that need heat treatment protocols designed specifically for AM processing.  For example, when made via AM processing with nitrogen-atomized powder,  SS17-4PH martensitic stainless steel components do not have the same yield stress or ductility as their wrought counterparts.  After proper homogenization and austenitizing steps followed by an H900 age, the yield and ultimate stresses and ductility generally exceed the wrought values.  Over the next few years, there will be new standards/specifications for composition that report the O2 and N2 levels in the powder as well as AM alloys with tweaked compositions to better accommodate AM processing.

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    Mark Stoudt
    Staff Scientist
    National Institute Standards & Technology
    Germantown MD
    (301) 975-6025
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    Data Ecosystem - Global Materials Platform


  • 6.  RE: Impact of additive manufacturing

    Posted 03-08-2022 14:41
    In near future we need to redefine what Additive Manufacturing really means to make a difference between 3D core/mold printing, and 3D metal/parts printing means.



    Data Ecosystem - Global Materials Platform


  • 7.  RE: Impact of additive manufacturing

    Posted 03-14-2022 07:02

    I'd like to just follow up on this with some supporting evidence. Again, specifically for 17-4, some literature [1-2] has speculated that the extremely fine grain sizes produced in an AM process like laser powder bed fusion alter the kinetics of austenite-to-martensite phase transition during the quenching stage of the solutionizing process for this alloy. I've seen Takaki et al. referenced to explain this [3]. It's certainly true that lots of authors (pick a paper w/ phase analysis of LPBF 17-4) have observed more retained austenite than expected in LPBF processed 17-4, even after a standard solutionizing and aging heat treatment.

    [2] Rafi, Patil, Starr, Stucker, 2014. https://doi.org/10.1007/s11665-014-1226-y.
    [3] Takaki, Fukunaga, Syarif, Tsuchiyama, 2004. https://doi.org/10.2320/matertrans.45.2245.


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    Jaime Berez
    j.m.berez@gmail.com
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    Data Ecosystem - Global Materials Platform


  • 8.  RE: Impact of additive manufacturing

    FASM
    Posted 03-15-2022 08:17
    Is it possible that there was some pickup of nitrogen during the powder bed fusion? That too would increase retained austenite.

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    John Grubb



    Data Ecosystem - Global Materials Platform


  • 9.  RE: Impact of additive manufacturing

    Posted 03-15-2022 08:31
    We did several studies to determine whether a nitrogen cover gas would influence the total content in the solid and the results showed the effect was negligible (same with argon).  The largest influence was the solubility of the nitrogen gas in the liquid phase prior to solidification.  FWIW, chemical analysis showed the nitrogen content actually decreased by a small amount (≈ 0.5%) during the build.

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    Mark R. Stoudt, FASM
    Staff Scientist
    National Institute Standards & Technology
    Germantown MD
    (301) 975-6025
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    Data Ecosystem - Global Materials Platform


  • 10.  RE: Impact of additive manufacturing

    Pittsburgh Chpt Admin
    Posted 03-15-2022 11:00
    Have sub-zero heat treatments for 17-4 PBF components been explored for complete martensite transformation?  It would be relatively simple to perform a cryogenic treatment on small AM parts than on larger forged/cast parts.  

    Getting low N powder would of course be the simplest solution for the part manufacturer.

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    Stephen Rooney
    R&D Metallurgist
    Ellwood Materials Technologies
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    Data Ecosystem - Global Materials Platform


  • 11.  RE: Impact of additive manufacturing

    Posted 03-15-2022 15:15
    We have performed quite a few studies with cryogenic HT in AM17-4.  The question that we have is, how appropriate is an LN2 quench in an industrial setting?  Right now, we believe the most effective approach is to pull the N2 out of the matrix to get the Ms temperature as high as possible beforehand.  That way a quench will be more effective, and we may not need to go to LN2, which can introduce distortion.  Wrought 17-4 transforms to approx 95 % martensite with an air cool, so unless we have a major breakthrough, it would appear that some form of quench may be something that we have to live with to get a comparable condition-A for N2-atomized powder.  That said, if the material isn't fully homogenized, an LN2 quench won't get you any improvement in the martensite phase fraction. 

    Your other comment is on point, the lower the N2 content the better.  One of our models shows that the transition is around 0.08 % N2, and if the N2 content exceeds 0.15 %, the material won't respond much at all.

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    Mark R. Stoudt, FASM
    Staff Scientist
    National Institute Standards & Technology
    Germantown MD
    (301) 975-6025
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    Data Ecosystem - Global Materials Platform


  • 12.  RE: Impact of additive manufacturing

    FASM
    Posted 03-16-2022 09:12
    Many standards for 17-4 require cooling to 50F (10C) maximum and holding. Inferring from this, room temperature (whatever that is) may not be sufficient to get complete transformation. Liquid nitrogen quenching may not be as effective as you think. Note this curve from the old ASM-MEI course on precipitation hardening stainless steels. 
    image.png
    There is a distinct C-curve and the nose is about -60C (-76F). Also note that transformation increases with time -- Martensite formation is not instantaneous.


    --
    John Grubb



    Data Ecosystem - Global Materials Platform


  • 13.  RE: Impact of additive manufacturing

    Pittsburgh Chpt Admin
    Posted 03-16-2022 13:05
    Interesting!  I don't often work in sub-zero quenching regimes, so this chart is new to me.  Not like other C-curve I've seen.

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    Stephen Rooney
    R&D Metallurgist
    Ellwood Materials Technologies
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    Data Ecosystem - Global Materials Platform


  • 14.  RE: Impact of additive manufacturing

    FASM
    Posted 03-16-2022 19:00
    Edited by Paul Mason 03-16-2022 19:01
      |   view attached

    My colleague, Ben Sutton gave a webinar for ASM last week on the application of CALPHAD based simulation tools to stainless steels and Ben included an example related to Additive Manufacturing of 17-4 PH Stainless Steel. The focus was more on the nitrogen effects of 17-4, but included a property model graph that showed predicted lath Ms temp as a heat map with grain size on y-axis and nitrogen concentration on x-axis (attached).  

    He said, in his judgement the problem is 3 fold. 

    1) residual segregation after the solution treatment can suppress Ms;

    2) small prior austenite grains can suppress Ms;

    3) elevated nitrogen concentrations (from N2 atomization or uptake from processing gas) can drastically reduce Ms

    It doesn't look like ASM have the on-demand recording of the webinar available yet but I believe it will be accessible from here:

    https://register.gotowebinar.com/register/2194323264494461199



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    Paul Mason
    President
    Thermo Calc Software Inc,Thermo-Calc Software Inc.
    McMurray PA
    (724) 518-7334
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    Data Ecosystem - Global Materials Platform