Quenching and Partitioning: Science and Technology

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Quenching and Partitioning: Science and Technology
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Quenching and partitioning: APMS conference
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A lecture given by John Speer, at the Adventures in the Physical Metallurgy of Steels (APMS) conference held in Cambridge University. The quench and partitioning process involves partial transformation to martensite, followed by an increase in temperature to permit the excess carbon to partition into the residual austenite. The quenching and partitioning (Q&P) concept was first introduced about a decade ago, to utilise carbon in as-quenched martensite to stabilise retained austenite and thereby enhance the mechanical properties. This presentation will provide an update of advancements made in understanding important aspects of physical metallurgy and microstructure development, within the authors laboratories and elsewhere, which have led to interest in Q&P as a potential route for producing commercial steels in volume. A variety of applications have been explored in Q&P laboratory investigations. Initial industrialisation has focused on automotive sheet steels, and substantial activity is now underway to meet aggressive near-term targets for vehicle lightweighting using Q&P steels or other novel approaches to generate microstructures with enhanced austenite fractions. The current status of some of these efforts will be reported.
Steel Hüttenindustrie Material
Steel Photographic processing
Giant (mythology)
Cartridge (firearms)
Sheet metal Club (weapon) Martin Brothers
Paper Last
Cartridge (firearms) Chemical substance
Photographic processing
Roll forming
Ship of the line
Vertical stabilizer Ship of the line
Hot working Ship of the line
Key (engineering)
Typesetting Outsourcing Ship class
Steel Cartridge (firearms) Material
Vertical stabilizer Turning
Steel Ship class
Steel Steel Ship class Photographic processing Photographic processing Vehicle Fuel economy in automobiles Vehicle Material
Steel Steel Material
Typesetting Airbus A300 Steel
Vertical stabilizer Steel Photographic processing Remotely operated underwater vehicle Printing Pistol
Photographic processing Engine Ship of the line Material
Typesetting Musical ensemble
Engine Last
Chemical substance
Vertical stabilizer Cartridge (firearms)
Steel Distribution board
Hot working Mechanic
Vertical stabilizer Temperature coefficient Cartridge (firearms) Ford Transit
Vertical stabilizer Typesetting Hot working Temperature coefficient Tool Ford Transit
Steel Mechanic
Allradantrieb Arbeitszylinder Steel Cartridge (firearms) Van
Steel Vehicle
Fulling Typesetting Roll forming Mechanic Cartridge (firearms) Spare part Musical ensemble Pistol Mixing (process engineering)
Stock (firearms) Printing
Steel Ship of the line Firearm Printing
Kordel <Schnur> Jig (tool) Spaceport Kopfstütze
Capital ship Steel Printing
Doorbell Turning Rapid transit Ship class Diving suit Last
Hot working Mechanic Carriage Spare part
Sizing Spare part Railroad car
and that is the only know the company and the only way to the end of the day and there it would be good if the thing and the next but John Wozniak who comes from the Colorado School of Mines which remained the center the city of research in the USA don't in 1 of the leaders step of going to bilk
about the Quentin budgeting process which studied you know fairly recently and has taken off all a number of papers you see and the granted by thing process being tried out in many different places really impressive thank
you for your kind introduction of Canada Kevin hearing from you OK so what's really a great pleasure to I want to be here today with all of you and and and I'm going to try to talk a little bit In the short time we have a little bit of science and a little technology alone I
acknowledge my my collaborators and co-authors David is in the room
here I I our acknowledgments were supposed to be on the 1st slide out but I thought as
I as I thought back on the development of this concept and although the process 1 of the great pleasures of paperless and we we often don't have the time or take the time and to read as much as we showed but I have an opportunity to to read a lot of the literature
from the Giants and and that was quite enjoyable process and I really acknowledged that those people who have that would influenced probably all of us in the room
here and I also want to thank the many collaborators and students that I have worked on this Over the years a little bit of
background I'm going back to the beginning of so this
quantity and purchasing process was really designed as a new concept to control retain and the the
original process concept was that week interrupts a quench so normally you would quench Austinite perhaps to room temperature and for Martin said but we interrupt the quench share
at a temperature where they might say transformation is incomplete and the idea that is some subsequent thermal treatment in there and at the same temperature is the quenching temperatures we called 1 step at some different temperatures to step down that
carbon would go from there From the Martin said into the on transformed Boston that would therefore stabilizer I'm so that 1 week then completed the quench too
back down room temperature we would have more retained Austin it's about the basic concept
of with extended their concepts and more recently and to the case where we may have industrial processing concepts and where the partitioning process have been on ice thermal and if we have
time at the end of my commited to about that this is a little bit more complicated but if for example in hot rolled sheet production and you use the right out table cooling process To complete tho partial Martin City transformation and then the coiling temperature where he won the club and would serve and to control the basically the time and temperature the cooling profile that would have
defined the extent of partitioning and that is the sort of process concepts that were thinking about in the
beginning of what we started but trying to understand With the thermodynamics would tell us
about what kind of competition could happen and how it could would affect the mike restriction properties of terror and so so this is some of the simple analysis from our and from our early papers
and again if you if you think about the matter stable equilibrium between Martin said last nite heavenward partition come to this point in equilibrium but in the
case where we have varying non equilibrium fractions of Austin and Martin said the if we analyze the person if the interface is immobile what would happen is the carbon would partitions filets a chemical potentials uniform and in the 2 phases that's why we have I'm
not a common tangent construction but and at a point where the the tangent intercepts on the carbon axis of the city in the interesting thing about this that is depending on the phase fractions and we could have
multiple multiple different conditions where the competence was very cool in the phases
and and so we can have very carbon enriched Austin much more than that I'm an equilibrium or less carbon enriched Austinite so depending on the phase fractions we can have some interesting carbon enrichment I'm in that went into the early development and then the next step of the process was tried to try to understand and how we would control Mike restrictions in that regard
this as an important and a diagram from Mark early literature and I wanted just walking through and for a moment so if we think about quenching Austinite and
so once the quench temperature goes below the 1 start temperature but the amount of Austin there remains is diminishing the amount of Martin said that forms during the quenching is increasing with under cooling and then so we stop at that quenched temperature
and then we partition the carbon and and most of the carbon would like to partition back into the Austinite and so depending on how much
Austinite Martin said a present that defines the the amount of carbon that can competitions in the US I'm
answer to this line right here tells you the carbon concentrations the Austinite if the minds that gives up all its carbon I to the 2 that Austinite and so if we have a lot of Martin said in just a little bit of Austinite carbon
enrichment let us not very great and and diminishes with With
reduced Martin said Constantine increased Austin and so that's so this tells you about the stability Of the
Austinite quench temperature after partitioning before we go the final pledge to room temperature and then depending on that stability this lines
only how much Of that Austinite that existed after petitioning will remain after final quenching so so so this is the amount of that Austinite that transforms too newmont insides of wishes subtract that from the Austinite that was present at the quench temperature and we get
this red line and that's the end result of this and that tells us how much Austinite we can retain at room temperature
and so this functional behavior was very important helping to guide and our our processing histories as we try to verify this concept of work so we have to speak In the behavior assessment of particular quenching temperatures embedded in this and fairly simple model where some
assumptions that are are pretty important from a physical minority standpoint and 1st of all we had ideal partitioning and all the carbon would like to to go into the Austinite and that we've
completely suppressed the precipitation of Carbide's a more conventional tempered reaction and that the to form the Martin said during quenching that you don't change the phase fractions anymore and that is that the interfaces are mobile and
that the Austin doesn't decompose in other ways like being formation so unbearable these assumptions are not always correct and and so did the source of a lot of interesting and follow up that we can do as a metallurgical community but still the model was very helpful to guide now that this particular
a model that I described here was actually applied more recently I'm in a completely different classes of steals the so-called
medium manganese deals that are of
very fine grain Inter critically annealed materials so fine their I Austinite mixtures and where the Austinite really stabilized by high manganese concentrations
end the shareholders diagram was applied in that case it's basically the same kind of behavior except in this case the and the far-right
Austinite fractions is controlled by the annealing temperature and so the greater
is the annealing temperature the more Austinite we have as a matter of manganese can partition partition into that Austin said and the US tonight is enriched with manganese but it really depends on the face fractions of so the more Austinite that you have the less manganese enrichment that you have and so the less stable is that Austinite and in terms of remaining at room temperature and so and depending on its stability the transformed one-sided 32 the filed quenching if we against Amtrak news from the US sniper that we end up with this black and blue
function that tells us how much Austin the minimum temperature
so a very similar the application of the same fundamentals to a completely different class of steals but and this
is actually helped work out 7 manganese I think point 1 carbon steel
this is the predicted Austinite fraction as a function of annealing temperature again assuming full manganese partition between the phases this is a long and healing time and these are the
experimental data showing that this this model was helpful to understand and the behavior of this other class of materials so
it's a it's a very exciting time in steel development now I think
and I'll go on the record as saying this might be 1 of the most exciting times for steel development ever the air in the automotive community there and the need for increased
fuel economy is dramatic and at least in the United States there is and there's a tremendous need for steel development too reduce weight and an enhanced vehicle performance or maintained vehicle performance
and so In terms of application of knowledge in petitioning and the automotive industry right now it is driving that an interest in applications but there are others interests in ball-bearings and heights of displayed steals and so there is as much opportunity that hasn't been explored yeah and quenching and petitioning but in the
automotive industry so we set out so-called a banana diagram before where we have this range of tensile the killer bees and tensile strength but for a whole
variety of different kinds of I'm Still materials and I heard this described in interestingly very recently biennials such data and General Motors as the miracle of steel so so we look at
this somewhat mundane way as well as experts in steel but the fact is by
small variations in composition and processing we can create tremendous windows a different steel products with very different properties miracle steel but
we're trying to push would try to push the property is up in the highest-rated hired killers
I'm so that's true challenging and any outbreak setting and for the community but how are we going to get there and so this is a and this is a simple model developed by my colleague David Matlock I'm really looking
at composite models for predicting uniform but Tildie based on phase properties and you can see if we if we look at combinations of Fred Martin said we get property combinations that you would expect that that fairly parallel to the different grades on the banana diagrams of fear play
steals if instead we will look at combinations of a particular stable Austinite mixed with Martin said but we get much better strength to combinations in this future need area of steels and and actually if instead of using stable Austin and we can control the
Austinite stability like I don't think we're going ahead to the US and stability In practice as well as we would like to and that we can we can move this curve around as well .period so it's a very interesting opportunities but in terms of how we get to the future of our philosophy in automotive still development is pretty much what we need to have retained Austinite like restrictions of so that's driving interest in human pistols but added How about day-night steals In media manganese steals as I mentioned I'm so very exciting time I there are a
number of things on the side but I want to mention and 1st of all this is all this data is on experimental data from Quentin petition steals
and some of the people who generated in the air in the room here but and this great she region over here this represents the original target that we set out to achieve but in
2003 and so we were pretty happy that that our development was fairly successful in getting son I'm high-strength materials with I was quite deductibility and the best
line and the solid line here at the same predicted Perth the last lap and so we were quite
happy about what's happened in the meantime and is that the property targets and heap getting more challenging and so 1 of the large automotive
companies in 2010 defined a target up here which is way up in the in the future a band of desired properties and the the next year but some targets here the United States Department of Energy has funded a integrated
computational materials engineering program with the industry and this sets an even greater targets and then the industry set
so when we think about how successful we are indeed in property targets we also have there were recognized that the and the challenge is increasing and so the targets are living and I promise that this
is my last banana diagram for this presentation original
models look that transformation behavior
and sentiment models that incorporated some petitioning kinetics and so this a subjective models you can say that the fear that gives up its carbon rather quickly and
it takes longer to equilibrate the Austin and
so what's interesting about that is that under certain petitions in areas and the Austinite might contain most of the common but with a non-uniform chemical composition Grady and we get some some interesting effects them when we tried to
I understand the stability of their last nite so we calculated using the cost and Margaret Margaret equations locally
but but in fact we don't know how that assumption itself so 1 of the questions for the community then and is what is the stability of Austin I and in in
the case where we have a local concentration gradient that's on the same scale and as the market said Micah structure
these are some examples of pledging partitioning I'm has been applied now in commercial steels at 1st
by Baosteel in China is a commercial applications and there are other companies around the world who I believe have a really interesting considering this technology I'm so in love in a few minutes there but that remain from my presentation I thought I had a presence in
curiosities challenges and opportunities we learned a
lot over the last 10 years but there's still a lot of things that we don't understand and hope with this community I will come back at some future time and and help so here are a few property
data so this is the product of tensile strength anyone gations worse is the amount of retained Austin
and and so Our desire was to produce high amounts of retained Austinite but you can see from this diagram and fact on the properties are not highly correlated with the fraction retained us and that's so I think that we still don't completely understand what controls the work hardening behavior and the
property combinations in the steals we've had a lot of partitioning mechanisms and some of the physical mythology and that the group leads led
us in this regard and 1 questions is about
carbide precipitation which generally speaking we don't want because it takes carbon from the Microsoft action that we would otherwise use for Austinite stabilization I'm showing by particular still that's the petitioner to different
temperatures in 1 case we get a lot of epsilon
transition Carbide's in my purse structure in the other case at higher temperatures and we get Austinite stabilization so for the community made 1 of the
challenges than it is and how do we control the stability of transition Carbide's other than perhaps temperature according to other models that we think we understand that that if
we could turn on and turned and transition garbage formation using other means and we understand how it would be a powerful our design tool the West the last comment I want to make without a lot of discussion about whether the 1 side Austinite interface is stationery mobile and there's been a some interesting modeling work that's been done it Delft in particular I
want of my former students Fred Thomas I look at some higher alloyed steels not not intended for commercial applications but intended to study the petitioning mechanisms and 1 of the things that we looked at as the change in the Austinite fraction during partitioning and in
these times deals where that it points to room temperature and petition subsequently found in any I'm high nickel containing still we found that the Austinite fraction was stable
it did in rich in carbon I'm so the the assumption of a stationary interface was pretty good In the case of high manganese steel that we actually and
increase the Austinite fractions during partitioning so and clearly we think the interface was not mobile
but even if the results of 7 green is the Austinite fares the the change from left to right as with partitioning and you could see come together they will still increase in Austinite fraction nickel steel approximately constant Osterman fractions and cylinders
Paul figure diagrams really looking at what happens to them like restriction during petitioning this is this is
manganese steel these colors represent Austinite orientations and so and these we think are probably the original Austinite brain orientations and confirming that which we think the Austin is
growing .period petitioning but rather than nuclear so but we don't completely understand why that happens in 1 steal and not another I think lot of bypass the sliding I'm going to the conclusion watching and
partitioning science and technology continues to the process is being commercialized and and
hopefully there will be other applications besides automotive she instills and growth in those applications
but what challenges and opportunities remain both in terms of science as well as in technology and and I am enclosing here
showing some unity Mike rastructure this is 1 that we obtained in a laboratory in a critically and old so we have varied yeah this is actually a commercially produced during the steel and that we have a mixture of Austin items and think that exceeds meat of Martin cited the cost of so that I
conclude my presentation
together thank you it was the few thank you very much its creating 1 of the modern concepts of automotive steel very distinct over the Olympic questions
I'm very full question music to mentioned Barrett is something that we don't want introduce pistols but could comment a bit more about it I understand that we don't want Bennett because he takes part of the country while point of mechanical
properties I expect that may be people should go in this direction to certain combining something that could have so I don't remember
saying that you know what they know but but I think that 1 when when when they life forms from From the Austinite at the petitioning temperature then you really have a mixed my prescription so you have accused mechanism wow but you also have they have lost tempering B'nai formation mechanism so you get a mixed Microsoft Archer and I think there are and there is some interesting properties that people are getting I think cases where they do have those kinds of mixed white rastructure so hybrid mechanism so I think they might actually be fairly important industrially and so on yes centers of
overnight stock as you mentioned the Serb media Monday Steele's Cesare probably were a hot topic at the moment and
apart from my niece I was still a painting on the range of fall farther and such like could eliminate all can and well I think there some aluminum and silicon wouldn't be strong Austinite stabilizes so you'd be looking at different concepts but those elements of the manganese is interesting because it allows us to really increase the cost of the retained Austin attractions to quite high levels and there are some other interesting concept particularly high aluminum were aluminum is being used to I reduce the density and still so those are different concepts that are a little bit outside the scope of the design concepts that I discussed today but but are also of considerable interest right now OK
effectively talk I have a question do not in the producers from Tomasa owned the high legal environment and he's steel and in which he is held
serves increasing deflection of also nite with a petition in the in the petitioning instead and
there II you wonder if I know that some of those temperatures in the diffusion Munyaneza assisting small but to Iusacell some articles from another researchers in which they think that the diffusion among Cesar underestimated at low temperatures so the using the same increase in the Austin a flat income due to some monies petitioning actually and so on I don't I don't know the answer to that exactly this is approved I mean this is a very low temperatures and thinking about it and I have been thinking about making his petitioning but I do agree but that's not necessarily this temperature regime but but but actually in the temperature regime of new line Of the media manganese deals so Indiana critical regime and we're getting much more manganese partitioning then you'd expect from a sort of published and the facility data so so I agree that manganese confusion there seems to be much faster than we thought it was
I don't know that that's I don't know that that's a contributor the the temperatures that Grant Thomas was looking at here
because if he definitely you have lower manganese levels did if you don't see those so I we don't upset the sudden increase in the fashionable cement but at those levels he observes that may be related it so what opening a maniacal still on "quotation mark think again thank you we have questioned him from the rest of the world have you from Medellin to have a question OK the
question is if if they're in the
critical enabling capital has been done in the 800 to 900 if possible for the monies to partition In the 100 seconds it's a good question and so so what are we talking about a media manganese steel I canceled so I guess it doesn't matter how but I think I think there's something in the recent literature that shows that you can get significant Mancunians partitioning I'm at Inter critical temperatures in a relatively short time and
the Christian from 18 deal Is it possible for all nominees Coburn interaction if you could come back to company introduction to like the
OK so so this this author is actually steel so I might have invented this but that and so is it possible that there is a a a
carbon nickel interaction is different than the carbon manganese interactions
and I haven't thought about that and this might not be a good venue years to be thinking out loud German I wonder even Dolce and explain it
to the mentality against that do so may be related to to carbon trapped in some places that you have information and should be considered said test
dislocations of tweens for all the interface sees because quaint team this deal before adapt that is so thin my aging you create our high dislocation densities I mean anyone for the Koblenz we'd be really comfort to those faces before petitioning to last and then maybe you hadn't Karbon In the process of current petitioning that kind note ruled out that kind of violence that do 124 .period with age the way of retaining do last room temperature at the end I have always said what we have hosts offsetting thereby by freeing by needy Castilo these have suits except when it is low temperature campaigns I'd around the temperature that we gated that down In that age silken writes that you to before bells it dislocation segregated incompatible can be at peace here because we've
tightened temperature a quarter of most fierce we evil if what we have seen in class status and after that there will be that definitely Asian site for rapid slogan right then I wonder if
he's that EU investigate dude dislocation densities signed the contract that those dissipation Yukon explains that the units or not all 3 it aims slogan by 2 or more or less Britain announced tonight of the yen injured Michael Stich there was a complicated question but but act I think I think part of the core of the question was with rolled carbon trapping clearing here and I think I I think ,comma trapping should be important and we've we've seen a lot of what what we have done ,comma announces we have seen instances where they were obviously not getting all the carbon out into the Austin so and it if we can't see if we can reach the kind of carbon enrichment that we projected from our thermodynamics if we could turn off the competing mechanisms we could really get some interesting carbon richness of carbon trapping is part of that I'm although in order to study that would answer Madam Provence to study you also have to understand that tampering reactions carbide precipitation so that's all challenging and we we we have completed that work yeah according
to dictatorial completion the diffusion of commonly skillful In addition to distance the
he did indeed desirable 5 Greek off tonight and I have to control defied
the reading of the so how we
control the size of the retain Austin as well the asked me the side should be limited to stand the retained all the time so so we haven't studied experimentally ourselves yeah the influence of 1 of the Austin starting Austinite brain size and morphology extensively but I have heard that there are some people who were working on Michael allied versions of of pricing and partitioning where they may be refined the Austin and and got some better mechanical properties right that the sides of the team "quotation mark tonight between right but we really want to do once you make the Austin and planted said then the Austinite Sison and morphologies control at that point you within the carbon around a common was reprimanded fast so you can the car the the mind's pretty quickly but if you want to change the Austinite tonight size of morphology you need to change the starting my prescription and that part we haven't got interior yet in the medium as
tears you mentioned that the petitioner the manganese quite critical to stabilize to
retain those tonight but I think the dairies also contribution from the refined grains so what heating up so what's the importance of their of grain refinement and easily so diagram refinement is going to help stabilize the Austin
and help increase the strength cells it is of that's it that's
a critical some aspect of Of the mike rastructure many Romanians deals that you have I'm very fine fearing an awesome it In the news and see


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