Non-­destructive non-contact microstructural characterization

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Non-­destructive non-contact microstructural characterization
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Microstructures without contact: APMS conference
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A lecture given by Claire Davis, at the Adventures in the Physical Metallurgy of Steels (APMS) conference held in Cambridge University. Presents the enticing story about the very rapid processing of steel to produce bainitic microstructures in milliseconds. The ability to non-destructively characterize microstructure is on most steel metallurgists wish list. Electromagnetic (EM) sensors can be used to quantify key microstructural features, not only that but they can be used on-line during steel processing for feedback control. EM sensors can already be used to monitor phase transformation in-situ during cooling after hot rolling, and recent work indicates that they can be used to quantify the phase balance in dual phase steels and therefore predict strength. This may mean that mechanical testing can be avoided, or at least reduced, when producing certain grades of steel, giving large cost and time saving to the steel industry. In the future in-situ systems to measure recrystallisation during annealing, or precipitate formation during tempering may be possible. Indeed there is potential to use different parameters from the complex EM signal response to characterise different steel microstructural features.
Material Chemical substance
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Typesetting Hot working Mechanic Steel Surface mining Commercial vehicle Commercial vehicle Semi-trailer truck Surface mining Material
Shuttle (weaving) Mechanic Automobile Commodore MAX Machine Hot isostatic pressing
Gentleman Caliber Mode of transport
Replica Material Singing
Steel Phase transition Spare part Monorail
Typesetting Hot working Phase transition
Phase transition Material
Typesetting Phase transition Gentleman Matrix (printing) Material
Connecting rod Engine-generator Tata Iron and Steel Company
Connecting rod Gentleman Material
Angle of attack Hot working Steel Gentleman Ship of the line Semi-trailer truck Casting defect
Angle of attack Cartridge (firearms) Spare part Bill of materials
Spray painting Material Water vapor Butler Rogers Baskett
Bauxitbergbau Switcher Surfboard Fulling Rolling (metalworking) Cartridge (firearms) Gentleman Plating Stream bed Book cover Material Van Photographic plate
Turning Phase transition Gentleman Ship of the line Spray painting Water vapor
Fulling Typesetting Mountain Gentleman Surface mining Hose coupling
Typesetting Volumetric flow rate Key (engineering) Remotely operated underwater vehicle Hose coupling Material
Barque Spare part Stationery Material
Volumetric flow rate Gentleman Firearm Aircraft carrier Surfboard
Typesetting Gentleman Deck (ship) Remotely operated underwater vehicle Material Movement (clockwork)
Spare part Movement (clockwork)
Steel Engine Singing
Extraction of petroleum Sizing Clothing sizes Material Multiple birth
Sizing Ship naming and launching Gentleman Food packaging Clothing sizes Multiple birth
Sizing Winterreifen Gentleman Clothing sizes Material Kranbau Aufnäher
Rail transport operations Stagecoach Singing
Pattern (sewing) Gentleman Material
Inflatable boat
Sizing Cartridge (firearms) Gentleman Monorail Material Material
Cartridge (firearms) Clothing sizes Presspassung Material Surfboard
Gentleman Material
Stagecoach Gentleman Differential (mechanical device) Finishing (textiles) Single-cylinder engine Van
Typesetting Roll forming Material Multiple birth
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Hot working Couch Material
Typesetting Ship breaking Capital ship Hot working Mechanic Stagecoach Bridge (nautical) Bending (metalworking) Engine-generator Kopfstütze Alcohol proof Photographic processing Spare part Bookbinding Engine Hose coupling Electric motor
but at the end of the day and that's it the the good afternoon Nunavut they have opened the 1st of the substance of this afternoon sessions and a 1st told is can be given by Professor Clive Davis
of the the University of Birmingham and it's examining nondestructive non-contact muscles recover translations between any
very natural that afternoon everyone wants to do and the
softening its stance to talk about how we might move forward in terms of characterizing materials and we've had a awful lot about Mike rastructure is and how much traffic control properties and importance of the wouldn't it be nice if we could get much structural information without having to cut up the sample without having to go through the process of sample preparation and I think there is quite a lot of answers that have been made to allowing us to get part way there and I'd like to talk a little bit about where we've got to and actually where things might go in the future in terms of being allowed allowing us to get that kind of information so once the current state of the art there
are a number of systems and I will say that today I'm only going to talk about Electromagnetic Systems acquired a lot of work has been done on ultrasonic systems as well
but today's 200 talk by electromagnetic so in terms of commercial achievement they're all systems that can be bought Boston I'm applied online during steel processing to extract information that comes died from my construction that's a lot of that moment is done to infer mechanical properties so that strip material for example can be released the customers based on 8 mechanic property without income property tax for or 2 the supplement mechanical properly tested and a lot of this work has been done for specific grades With empirical the semi empirical correlations they went extremely well however as we start to change the steel type change the process into the mike structures change suddenly there empirical relationship but necessary work so with parlay that in terms of being able to get much of the information and has properties that cleverly lose quite a bit more that needs to be done the kinds of things that can that
can be done already on but some examples of appear quite a lot in the literature where there's been relationships between a magnetic properties electromagnetic properties and a laser mechanical property information security creep life or indeed
might shuttle information that we might measure by my techniques such as metal graffiti such as press fraction this is and get this
:colon information "quotation mark land lab-based tests that can do that but in order to have
something that is much more generically useful so that somebody can use this take it with a different still times without having lost calibration samples which is where we can't he said we need to take this a little bit further so in terms of thinking about motivation and challenge is to
move the the field forward nonsexual evaluation then we have several aspects there is a need and a desire to have to do online Mike structural assessment because that's something we called him at all of you can't stop the mill halfway through and look at the hot like rastructure dynamically so there's
quite a lot of of desire to not just infirmary structure through and modeling and temperature information but to get some kind of direct measure is directly related to my perception there's also a design the in-situ inspection where moments it may be 3 inferred from Harvard's measurements all possibly by looking at replicas you get my such information that surfaced dominated he might want to look deeper into the material and indeed ultimately went to be nice if we could measure all Microsoft ruptures in complex materials and nondestructive so I thought I'd talk a little bit about where things have got to and then some of the other scientific basis of how this this field is developing and wet weather challenges are to take joint firm prudently
transformation monitoring this is very much looking at in-situ measurements during steel processing then very nice large signal changes we talk about going from Mossadeq phase to any of the other part faces very perlite day-night Martin generally want
provided below the Curie temperature and we go from power magnetic face-to-face magnetic phase and then get lost signal changes here report it is an
output from electromagnetic sensors and all I'll explain a little bit about different measurement of values and in a little while but this is 1 that can be taken out as we go down but little little jump here which is the Curie point because I meeting notices and we still we get a little bit of far-right forming before the ban transformation we pick up graceful volume fraction of far-right not that signal change corresponds to about 3 3 % far-right faction formation and then we get the transformation here
does quite nicely improving allowed it's nice if you want you know that's fine really the challenges to take out beyond land-based to you production inspection in order not to just rely on empirical correlations there needs to be the fundamental and applied modeling work with fundamental relationships that underpin the signal In order to do that again
is a relatively simple example then there too 2 other aspects that need to be considered 1 is to consider the matter intrinsic magnetic properties of the material and the 2nd 1 is to consider the properties of picture sensor design and the target geometry of the component you inspected sites in terms of
looking at the intrinsic properties of the Microsoft rupture the then news and very modeling technologies listed commercial package but with imported Mike structure information was being represented here at all the
far-right during formations in the far-right forming around Paris migrant boundaries for example we How magnetic Austin Semitic matrix and the net
result you can you can extract out the magnetic properties of that material going through a transformation here we have a representation of the sensor
system target material and the sense and therefore you can get the magnetic lines of
flux generated for particular sense of our target generation bring those 2 things together and then you can get out what you expect fantasy for a particular might prescription for a given and component and geometry less quite nice that the fundamentals is there are not just looking at correlations terms of where things have reached will we've reached the point where and some of the sensors are now being used online the beginnings of a phase
transformations are starting off what what actually is the easiest thing to look at it signal change that here we have an example of this is being done in collaboration with Tata Steel and it takes application was for wrought material and so we have we
material coming out onto the run table here and sensors below roared and I think it's quite nice example of where
actually complex target material can be examined role is not ideal but trying to do nondestructive evaluation of that is a difficult geometry you look
at the way that the world ladies in wax that comes along this runout table then you know
as a sure how much talk maturity you've got ahead of you or your sense that had this is difficult very difficult manufacturing challenge to toys come get me back this idea that there's different magnetic signals and different it's a sensor signal meeting you can take up this matter little who work that was done by all collaborators at Manchester
found that if we take a particular aspect to of the phase angle you can come liftoff and Tom get a John tree relatively insensitive to provide you've got your hot steel that you not then going to worry radio signal changing your different amounts of steel that you're just looking at the transformation the way through this nice fundamental work the modeling fits alongside
legislature again show where this technology reaches for this is the output this problem important
ground here we got to an output signal in this particular case phase angle with time and I'm showing the signal for 2 "quotation mark bills
as they come through what you can see here will hopefully
the initially we get a signal with a very large phase angle this drops down and we gotta come quite constant below phase angle for the remaining part of the "quotation mark what this
translates as it is the 1st bit of the oil as it comes out and goes on to the table and comes out before the water sprays is switched on so this is unfounded formed and most brazen switched on in this particular position of where the center is located at Rogers then fully transformed so we can clearly see UN transformed or
fascinating material here and the remaining being around magnetic so it's transformed into politics take which is what was I was designed Why
is this kind of thing useful while 1 this would be useful for production point of view that you know exactly how much material from the view of coil that hasn't reached my structure under cover conditions we want to more would be cut off which we inspect so that you can measure properties for release specifications but more than that you can start to use arrays and Mike restrictions we talk about uniformity sometimes we want uniformity of originating in we've had some cases we don't want it but we do want to know is we have to measure what we have when we got Parliament here what we want uniforms you would not want to make new example using an
array of sensors and this was a full rolled plates material in a pilot plant millet Tata still coming out halt lenders going over a bed of array of sensors we can map the transformation so and John color scale and we can map the transformation 1 as is happening in an overtime but also looking at it spatially in terms of how cooling might affect many
I haven't mentioned is quite useful it is the electromagnetic take techniques I'm not sensitive to water spray not sensitive to dust so we can put it in play aggressive environments which is a nice advantage so the breeze summary of where things are and then House
where we might want to get an amendments the online systems for face transformation of our own a taking off so
various systems as you've seen in rod mills there's a couple of systems now In a full trial systems in strip mills and fact was switched on and started running just over a month ago was starting to get data mountain districts stills a different types still went restrictions we can model what would expect given my construction we can take into account different target geometry however that's that's for relatively simple my social changes were talking about phase transformations now we
can take into it too account spatial variations if you have abandoned like rastructure coding will know the far-right perlite and Mike structures or some other ones will wear would have a composition segregation we can take into
account funded bonded materials but that's quite nice but really what we need is something that can deal with even more complex might restrictions when we got more than 1 variable changes In order to be able to extract information that is much more detail about that much structure have to go back to what we mean by or what type of magnetic behavior we have and therefore what aspect of researchers sensitive to different magnetic behaviors become we extract more data from the system so this is showing
a pH curve of the material I want to illustrate a couple of key Keith sectors within this so we can link now what's going on
from the magnetic behavior to the mike structural behavior for a lot
of what we've done so far is dealing with the initial magnetite stations to have a material was obviously halt it has no prior magnetic history starting with the material aromatic notes magnetic and history and applying very small feels the
1 I've been talking about so far has been very much in this area we look at the initial permeability which is the slow this initial part :colon
all these years you start to apply a field you started to change the magnetic behavior the main structure and we get different aspects of Delta saturation and here we
have found the remnants at this point here you'll find in the
literature quite a lot of people measure remnants values and related it's too much of valued at any point if you look at the
I'm quite detailed you see that these are not the kind that have lost up to them about how we get magnetic Parkinson Norway's information but the difficulty is is trying to relate this Mike structure information we have the carrier acidity and late from minute talk about the permeability as you go and
sweep around BHP to have in mind the fact we got these different types of values writing was more important is how does this relate to the Microsoft structure and magnetic character because we want much of information in the deck this is not at the bottom part and
come through top each what what we need to try and visualizes the idea and magnetic domains in material and to go through pH curve than you have movement after main walls
magnetic domain walls as they move will interact with
much structural features that is pending points and so we start to get this idea of magnetic behavior being legend Michael structure because the mike
structural features pin magnetic domain walls or there be worrying about many more movement than what we've been looking at so far as the initial
part down here where the demand from actually being moving at great distance they just
locally it not moving they've just been warbling they still would influence of any prejudice not apply higher fails you can insult to overcome pinning points and then the concept here becomes important is how strong underpinning points and how many voting points to overcome as we quite different levels field and if we can reverse engineering that we can say with this field would we overcoming these much of which is that we get information about the specific features OK in order to to do that's not just in theory we need to be able to observe the interaction between Mike structure and the magnetic properties the example and offset the
more phase of what we mean by domains within steal some of you may be familiar with with magnets or indeed electrical steels widow of engineering steels quite a bit more complex and the 2 main structures of the generally fine looking at these 2 main
structures that we have pockets would parallel the main walls going to be looking at these main walls how they how they moved and you can see the kids of demand to link through to
Michael structure and we need to start the war how do all helped different aspects of my construction affected the domain structure and hence the consensus of the article to
images the hopefully sitting there looking at going in exactly the same they all are pretty much the same as the only difference is the size scale not because this material has a grain size the answer may come still who told AFP )right parenthesis is much smaller behavior all cleared the main packets and what we've done it is linked the main track it's to my extraction aside
grain size so just overlaying the grain structure image with a magnitude domain image of previous images I
showed you define 1 1 magnetic domain packets per far-right
brain interestingly and you start to increase grain size you start seeing multiple
packets per cent migrated to this lovely launch fell like rain in the middle you can see hopefully you can see that they're all different packets of main package with different orientations this grain
as 1 the main track tracking orientation in it's been a very large cranes at his best we've got different domain and in terms
of linking Michael structure to 2 features but if you
take those the conditions where you just called 1 of the main per size they can get very nice correlations between the um magnetic properties material arrested permeability for local field just wobbling these 2 main walls and grain size follows a whole patch time relationship
you can start to build up a relationship between individual magnetic features and of the magnetic behavior and therefore the signals that some nominees Chris not really developing as an allowing us to look at the complex Mike restrictions which is where we want to get invention the next stages say OK we want to move to complex micro-sculptures then we need to take domain walls past we pinning points on 2 major pending not to sweep through at pH separating out Mike structural features of info In order to do that we want to what 1 better measure pending strength but to be able to observe table direct correlations between what measurement you have and that the the what happened physically within them to those with me researchers in the
great have developed system for dynamic observation of demand motion so we have and samples within coils and then a just putting on a high-speed camera to observe today's through now has to images this
is a way of saying is that the same material overladen rate is the grain structure and within that what we've got
is that the described as a good example of how perceived parallel the main walls and this is
the static domain past pattern without any
applied field if you apply it feels like to be the main walls have now moved with changed the internal demand structure so we've got some of these the walls the the closure domains changing as well is an example ago complex domain structure you can see again how domain walls of my move
and what we can do is watch this is using videos actually Seattle ply the feel the domain walls moving backwards and forwards in overcoming putting .period as you increase the field you can watch how fathers domain and was men In order to do this stated further we then need to relate to the main structure and the arts Out of magnetic properties to
specific much of features here taking mean free path demand more motions that example taking measurements of societies all into particles spacing sisal grain size a relate that to the fundamental material property I'm very quick like to
just show a case study of how this can be applied to retain
complex steals protect complex such as pay 91 power-generation steals then 1 shows and some differences that can be obtained by looking at complex much structures so in this
particular case want to 91 steals the only difference between them if the Aluminium luncheon ratio which affects the other amounts of Annex precipitates within the material so that it this is what has been done on the materials and that we've been given what we then donned his right this reaction
signals very importantly if we're looking now relating what we know to what's going on a method to properties we look at for example lost mg to which a temperature time parameters we can see that initial behavior of material there's no sensitivity of electromagnetic signals even tho we know much
structural features changes that's clinical competing features so we're using for example dislocation density which acts as a penny .period gaining precipitation so the 2 offset each other without the increase in signal if we move to the other material with
exactly same behavior this increase here without it costing is deferred to a later time much of this material has many more pinning precipitates never script pages factorization behaving that we can also see
the clear differentiation between the materials because of the different features more MX precipitates out and therefore ii out different signal to differentiate between the 2 really well and finish
with that is to say that we're starting to get to the point where you can clearly defined much social features and how they impact the next stage is to sweep
through do little little walls domain walls as you go through so you can start to see how the different much social features will affect the whole summarize here
probably it with a question really for audience is the idea is where will we be going in future it's not just where we are now and I think that in the
future there be an awful lot of electromagnetic also ultrasonic type signals where we no longer need to always Major Mike rastructure will be of general form of information out from these non-destructive methods and thank
you for most of the questions and you wouldn't say hi and thanks I was really interesting I have a couple of questions firstly on it are there any kind of resolution limits to to either of these 2 techniques in terms of how refined might restructure you could theoretically all you can it look at yes that there all going to be some for the 1st thing is you need to have features that interest of the domain walls and so depends on the nature of the domain wall and what might structural features as to how strong my attraction is and where there is a significant contraction all said so there are going to be some aspects of the can't do I think the biggest challenge to the places where you got competing factors which is where the P 91 out it is not the answer to everything and that's why it needs to be a fundamental understanding not just purely an empirical correlations to be able to say what can you measure and under what circumstances and the
question was with the magnetic testing and the ICU using just as parents sample and putting them in in coil so it is it is not something that you periods of theoretically transfer
onto the production we actually be done that in terms of fate transformation recent use little prepared samples because we want to observe the March structure as we planned field then you just designer sensor for a particular target application sofas all example or the team work with Manchester designing now tube inspections for problem so yes this is not limited to 2 slap that was really the key point is it's not just that based on measurements that this can be transferred to a number of different environments to an end as quickly and what's the influence of the fact that you've got like a three-dimensional like restricted you're trying to translate in in what we see is two-dimensional images is it just a surface that you love you have that you have to take into account what it spends again what it is you're looking at whether you can assume that you've got something that is the uniform Vermont native and take into account three-dimensional nature to summer models we can run we run three-dimensional models is more computing power so you run that when you have to have the deal with 2 d if you can assume symmetry state-of-the-art site he thinks like you can attend the last some the limitations in the fight using electromagnetic fields and therefore you have a skin depth fact so depending on how you design your sense what material is as to how deep you go through to use multi frequency sensing so the high-frequency Geneva resurfaced dominated the news low frequencies sold or place Trixie can penetrate deeper into the thinking good OK and
it's a similar questions that previously actually at work station reservations can you get the sense that you have a very Hatcher genius and specimen with thinking this power
plant components Lee might have something do their part which is experienced most stresses and is in a high degree of my visit to the generation have closed the things you have a moment pinpoint that it there is no single answer to that it depends really what you're designing to do too few particularly wanted to look at very fine scale the new designs sensors that had and for example where the magnetic poles the break close together CPU command map on a local level of difficulty with matters that needed which was surface dominated Yukon is signalling very far if you're looking at something where you want to know what average looking at a bowl property then you may signal morning design different types of sensors that some of this can be done by sensor design which is part of the reason why this work has to be collaborative they have to work with electronic engineers electrical engineers for example which is what we do says no single answer to your question what you mean by close together the communicative mm a couple my microphones number emblazoned we we haven't gone down to looking at things on the sub-millimeter level is not something that can strengthen the work of winter there is on the rise work with people looking at miniature sensors I'm and so therefore there is potential for doing that but until we've understood the relationship between the signal and the micro structure to make sure the fundamentally new Commission the things of interest that might be happening on that sub-millimeter scale if you do it when you push the development on the sense when you push on on the relationship this moment is quite lost long relationships and designing sensors that can exist in robusta environments and assisting tens of this weekend's actually what usually happens in every instance system that the defamation committed by local affiliate complained local theater measuring something which is actually over the whole specimen in getting them we're not looking at create but create failure this is still very early stage in terms of my rastructure changes to you've not got any creep damage developing in it's in the nature of the when looking at a big actual right if you don't have to wait getting local local deformation mechanisms and yes and then he would do this design something to look at that if that becomes that the priority to the capital area in the month use with direction of the real world we live in the West and the rest of the world good yes yes I yes I agree the crystallography becomes very important to produce the the of I'm yes something I didn't go into the toll we have done work by for example we've an ABS statehood at Chris orientation or grain orientation and look at how the domains interact with um or how the main walls moved within different grades of different orientation the amount that would then allow different orientation effects likewise we In which is my constructions where for example you might have abandoned my prescription depending on how this field is applied Europe .period parallel perpendicular to the mike structure binding you'll get different results with those of things that we have started to be able to take into account the summit of the union is going to be we used to say yes yes it was good of humanity whose the government money to get to the core of the that has said it is not substantially year which is a massive most of New York quite right and that's the thing with this kind of work is that those factors can be taken into account it's you pick off you can call the the features of most interest sort of the boldfaced transformation because that was what the time halt but now looking back at what the most easy thing to do if you start to go down the list of things that you're you're interested in so looking at that time I type aspect it's on the list today but it's it's something that and that's why leave
this with how far can we get because of bats not reached yet but that is something that can be done with it would go on for ever got to the bottom of the


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