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Modern Steel Products (2015) - lecture 3

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that's a good morning everybody the a
slight to change 2 from of the slides to atone for on the he class so that you may want to check if you're missing 1 "quotation mark
slides or something that and should be easy to recognize 1
of the changes I've made it
was his duty to remark of
1 of you came to me after class and testing
it's 1 of the remarks move
was correct some slight 38 and in this mind you probably have the copied from printed from the new class size you'll seated ice and alright following element can we result in letters contraction and I wrote silicon and in the original has an aluminum I think found that some wrong aluminum should be here with the glasses expansion and it instead it's phosphorus that I meant to right but whether it was I don't remember who was with 1 head probably heard about the lightweight steals might which still research and and there's kind of it's strange to him that aluminum would be In the loudest contruction group so this some information here just if you're interested so
allying elements to result in lattice contraction or expansion that's related to the and the size of the atom relative to that of fire and so have you I will post this summer in the new version of the slides for the introduction on the class so you'll you'll be able to find it in in at this afternoon already have spent it so desire this is the periodic table of elements are the elements that are indicated on the the main allying elements in steals and I've indicated the atomic radio I sue the irony is that is actually a relatively small bands the Parliament as they come along .period 120 the point you want to follow nanometers many stops size then the green elements are the ones in Europe larger in size and there orange ones are the ones the smaller in size Of course it's what you expect that some of the things are expected of aluminum is you can see here are considerably larger in size even tho it's lighter the lose and stand at the moment and so as a consequence if you want if you alloy the the overtures and in contrast silicon which is incense sticks to it is a considerably smaller yes so so if you alloy Byron the I went to Lumina of you and you measure the lattice parameter the measure the lattice parameter here this year this is between these 2 items they the unit-cell before I but when you are lightweight aluminum you'll have considerable expansion of the you Allenwood silicon you'll have contraction but had these 2 elements atoms being lighter than irony this means following with aluminum will give you all the density decreases this 1 with silicon will have if you increase in density this despite the fact that the silicon smaller cars that's a thank you very much for noticing this so you've got some additional material to learn as a consequence so right good so let's continue now where With lecture so we
had talked about you you checked for
transformation and the we had to if I'm right we it's
target With the discussion of the
kind that and discussed
about growth and
together we cover a lot of material because I assumed that at 1 time of or another most of you we would have seeing
this with the material men and we
had ended with the introduction of spare which which is the MicroStrategy you get if you take care of steel Irish carbon alloy I knew a lot a meal for a very long time and you get the the the equilibrium like rastructure which consists not of this Lamela structure but of this this globules of semen charges the small globules of semen tight here in new CDs larger grains here in the in fair granted that's that's actually the but equally room of Microsoft very soft Mike restricted and there are many of deals that are not used in this With this might restrict budget you use this MicroStrategy make them softer so you can process that you can of plastic Lee easily plastic deformed so there are lots of products that go through this might rastructure yes ball bearings for instance or I fasteners or bolts well will go will pass this might MicroStrategy before getting there the final Microsoft because this is a very soft intermediate Mike rastructure but finally you can also instead of own but in doing the transformation from Austinite to room temperature or lower but by quenching so that you get a transformation that where there is absolutely no diffusion and you know that this transformation leads to this transformation salt Martin said take diffusion was transformation and depending on the carbon content you you your cubic sent you a pubic by unit-cell can become a two-track the crystal structure if there is a lot of carbon in Super saturation this well lots of carbon that means that you typically have more than 0 . 2 percentage of carbon then you will see this the 2 tribunal distortions lower carbon contents you do not see it and and and this is an example here of the March acidic Mike restricted this is a high-carbon Martin site Mike rastructure knew you concede is very typical Martin citic Mike rastructure however that this sort of the Martin citic transformation in steals 2 surly technical standard in engineering steels is the kind that Texas depend only on the temperature not not a time we say that this kind of transformation is :colon in thermal marked the transformation what what does this mean if those who remember the young the transformation to perlite so so if I do the transformation for instance using this temperature those cycle where gamma decomposes too perlite and and perlite is basically a mixture of variety seem tight trade that is the growth nuclear fission and growth process so it's too it's that kind antics are both time and temperature dependent relatives fight if I'm at a certain temperature the transformation have this this type of of the kind that extracts and not sold in the Martin citic transformation and of much of the transformation is only depends on the temperature so as a consequence of the transformation for Martin side of horizontal lines there's a horizontal line if if you go you can quench down 2 this temperature you make a little over 50 per cent of the Martin site is transformed into this 50 per cent of the Austinite is transformed tomato and if you stick to to this temperature nothing will happen will not make more Martin side that's basically they the situation is frozen if you want to make more Martin you have you will need to decrease through so if you want have 90 per cent or more Martin said you have to cool down further yes that's time independent the important aspect of the transformation have it enough fought for most feels that now having said this many different types of Martin's item Arkansas transformations of the duo behave in this way by nuclear nation and growth but that the Martin sites you deal with in steals is the thermal you can and up the
usual Mike rastructure so that we see is a very fine it's it's this is what we call low carbon black market inside is very complex complex and there's a lot of Mike rastructure involved here and there and the reason s is because when you do a transformation from a Austinite fair also lied to fluoride new transport unit sale Austinite too the unit itself unit sales of come on you know this units of Austinite can transform too multiple in fact 24 different but equivalent orientations for fairer and then this happens all the time so it's difficult Austinite grain will be subdivided In 2 an equivalent but differently oriented well Martin sites unit sets and that that is the reason why 1 of the reasons why the structure is considerably refight 1 big also migraine gives rise to what we call packets the package I and these packets themselves Our subdivided in what we call walks and the bloc's themselves consists of parallel lasts that this so you get a considerable refinement of the Microsoft truck and although Martin site is basically nothing else and far-right in crystal of graphically because you get is very large refinement of the MicroStrategy Martin side tends to be harder than fairer and that the the concept that Martin site is hard and brittle there is strictly spoken not correct Martin site can be His Martin side is the result of a Martin citic transformation which is a diffusion was transferred so it doesn't mean that the the Martin constituent has to be brittle and hard hit brittleness and the hardness of the MarketSite site is mainly the consequence of the very high carbon content that you have in Super saturation if you have a very low carbon Martin said it's pretty soft and it doesn't have to be brittle really and right so this is
an example of high carbon Martin cited issue democracy at very different you still see these very light larger flats of March site in this case and then in between UC regions where this they're very smooth and gray that is also note that hasn't transformed and will not transform yes it's what we call repainted and transform the retained Austin and it's it's the proof that the Martin said transformation is time independent because this this and transformed Austinite will stay there forever on last I cool down this Mike restricted to 0 temperatures and that will create more Martin OK so you can have this retained Austinite said if this particular well so this is a particularly high carbon steel and if I if I Kool-Aid like this I will get to transformation products like variety and tied them if I if I cool down 2 the law to room temperature and in this particular case the MS temperature is here and the MF temperature is there the matter is the MarketSite site finished temperature when everything is going so that this particular steel I transformed to room temperature yes From the image here probably 50 per cent this transformed to To Martin site the rest is owned transform bright and it doesn't matter how long I keep it at room temperature this Austinite will not transform if I want to make it Everything Martin said I will need to cool down yes so the Martin said the kinetics of the democracy transmission are not time dependence yes no no time dependence Intel now that the structure itself there is so Is there is formed by shearing process and the Austinite transforms override by shearing process and so this will be the 2nd year of a 1 1 1 planes in Austin I think there's a new concede on this side you have a 1 1 1 playing against but the the share is presented here so this side here of 1 1 1 of this 1 1 playing becomes a straight straight flat playing it's not inclined anymore and that stung by every the plane of atoms being shared in equal amounts can end this and sharing will will cause the structure of the crystal structure to change from FCC to bcc lattice directions
what what you see that on the macro scale depends very much on the on the steel that you have differences this is a larger magnification of this high-carbon steel you can see the Martin site last this is Byron manganese yes the the Martin cited you form here is it's much more played like give to the type
of Martin we get this directive note this is Martin side when there is enough carbon in it as well for 8 you hide constitutive high-strength constituent which we which we used in many engineering steels has endit this very widespread use of inside Mike rastructure in steals that that the risk is connected with the concept it's called Hardin ability this hard ability concept is a describes as a description of how easy you can make Martin sites Mike rastructure in a steel mill so let me show you how we measure hard ability 1st you do in in technical circumstances you use what's called the standardized the hard ability tests and the most famous 1 is called the Germany and quench test but there are alternatives but let's have a 1st look at it this job many test so what you do is you make this you take this bar here you can see it's a it's a cylindrical bar of steel shares during this test it's a red-hot you may put it in a survey in there to in the a furnace 2 a temperature where it's fully also denies ties 900 deg C typically has and then you put it into this whole there has .period take down this and then you Have a water jets that quenches the end of the cylindrical body and you can see this is that the water flow what'd chat spreading sideways as you as you quench the top and the quenched and now is black here is because it's colder and QC gradually the Black the dark and the increases in size as you cool down this this bar right so you have cooling rates which are very high on the quench and and decreased as you go away from the quenched on so as watch would usually then do you take this sample out when it's cool down so this is the sample viewed sideways this was the and that's quenched and you make a hardness measurements and what you usually find is that of a steel will have a very high hardness where the steel has been quenched yes so if I calling rates here are very high and the cooling rates here in the bar are much lower accordingly so in but the quench and have this cooling rate somewhere away from the quenched and I have this cooling rate so for this particular steel has I will form here I I will for Martin and here a little form varieties and the tied mixture for instance by 9 perlite however if I have a steel so so there is room temperature here and I have the same cooling rates this cooling rates that this point and this cooling rates that so much lower cooling rate this at this point but this steel I'm using has different transformations kind that excessive different TGT diagram and for instance it has this died the transformation of the compositions the reaction the secrets of the people that are on the right so as a consequence this same cooling rates I will get marked inside here and that Martin side there so we say this deal it has a higher Hardin ability then listed alternatively you can you can do it with this quenched and perfect you go there also the quench tests where users cylindrical bar yes and you spray water on all sides so it's quenched on the other side and in the interior the cooling rate is lower so if you take this sample you then make a hardness test usually you'll find at the surface is hardened and in the center as this is less hard because there's less Martin side there what would you've made constituents that are not so hard I it that against this these tests are very standardized and so on and their use in in the following way princess example here of how how how you work with this a charming test a let's have a look had 3 steals which which contains . 4 Percent of carbon . 4 per cent . 2 2 . 3 . 4 per cent of current is of isn't normal carbon content in engineering steels and that so we have 3 grades the and degrade denominations that I'm using here will talk about this in the later on about centralization sits of the so-called AIS grain denominations 2040 the 86 40 steel and 40 340 steel and the 40 obviously is related to this point for carbon is this these last 2 digits is 100 times carbon content in mass and and then the other digits are related to the composition because of this 1 is 8 unalloyed steel doesn't contain much of the following that much in terms of allying element except carbon
and the 2nd steel here 640 contains some chromium and some molybdenum and then the last 43 40 contains a lot more manganese . 8 chromium and . 25 and you can see me that if you measure the hardness This is Rockwell C hardness scale Nunez as a function of the distance from the quenched and you see that all of them Our Martin said at the surface and at the surface of my children the text because I have very high cooling rates however as we go away from the quenched and the cooling rate decreases and the unalloyed steel is very sensitive to this yes the cooling rate is too low To get hard Martin signed form away from the quenched and because you have this behavior we have lower calling rates you form softer constituents 4 lines like that very nite that a softer than Martin side so you get a very big drop in the the partners at the top 1 is almost insensitive to the cooling rate that I can I can be at the quenched and yes but very far from the Quentin I still have a pretty appreciable the hardness of this material is very hard and the intermediate 186 40 there was a fight concede that it drops off and this is the hottest thing that I can relate the hardness because I measure homicidal when you measure the hardest you don't measure you don't Malaga fleet analyze the my perspective just measure harder however we can relate hardness with the amount of Martin site that's for them so this is this is this lot here but this is the the Rockwell Seascale and this is carbon content all right and so on let's just have a look at 100 % Martin side and that's 99 % Martin site might restrictive and what we see is that as we increased that carbon In the Martin side has the hardness increases so if I had very low carbon in Demotte side it's a soft Martin's if I have a lot of carbon like . 7 the hardness very hot so the and so if we look at this point here yes the microscopic is a fully Martin said to have fully Martin said so Mike rastructure fully Martin said . 4 carbon yes the . 4 carbon fully Martin said Take This is the hardest that's why I know that here it's fully Martin said because of the hardness not not because somebody's told me that because I think I know here if I have point for carbon yes I think I should have about a little bit over 60 5 the sorry 55 Rockwell hard but so what does it mean here What Is the What is the Martin site content here for instance it's a let's have a look I I look at this scale the Rockwell hardness and said this is the hardest I measure and this is my carbon content and they intersect on 50 cent of Martin's I regret this means here at a depth of about half an inch about 1 . 2 cm yes I will have a 50 per cent of Martin's book that's what it means so I went this area Germany tested in very conveniently described the Hon ability of material compared a hard ability and also say you know how much Martin side you've made but at a particular spot and so with this grade 86 40 50 % Martin site at the distance slightly larger than half an inch away from the quench :colon Laura no obviously you know there are very few engineering products did that look like John many box likely they're worried you not not many I can think of it as so that's a standardized tests very often the products but there were used to harden ability concepts are barred like products the borrower like products with Sabara like products well for instance this here the crankshaft Of the motor and it's a very common application for however Boris yes and for engineering students it is all all the cars have 1 of these and the other products that look like this in the powertrain of of cars which are Bora based as to how do we relates the results of the the Johnny tasked with this Bora diameter yes can and does this have an impact on the on the steel their use 1st of all so that's it that's 1 point again so that the relation between distance from quenched and end BA diameters yes the 2nd thing we we have to realize is that but when we I do but quench fast With the Germany is a very simple you have the water at room temperature yes and you basically jacket
against the surface of yours the bar so you have extremely high cooling rates this not technically there many reasons why you don't do this Europe the cooling rates that you apply the cooling the media that you apply not as severe as and 1 of the reasons why we don't do this is forints to avoid the formation of small cracks and when you have to do so you have a massive bomb units you Kool-Aid what happens In Euclid and you get a very severe cooling the Allah and the other end well contract that's true contract because of thermal contraction the inside is not as cold 2 dozen contract at the same rate as a consequence you get tensile stresses at the surface and there may be very high if you cool very severely so you may have cracks you don't like cracks we certainly don't like cracks in crankshaft because you've got the team I fatigue effects you may get for instance breakage fracture fatigue fracture as a consequence of the scripts of the many reasons why we don't want to do very severe cooling yeah that's a reason is that when you do this kind of severe calling you may also be a distortion of the oldest interviewed many reasons why very often we don't do what is called an ideal quench an ideal quench is a extremely hard very fast quench so you can do water clenched circulating water which still water you can do oil .period and and and these are unless the again but was it let's have a look at the meaning you how do we transposed are Germany test results that went with it the I'm with actual information that we can use in practice so on we just knew that it is 86 14 Tennessee gave me 50 per cent of side at a distance of about half an inch away from the what is this in term of cylindrical body which is what I'm interested in if I'm making crankshafts for instance well but this is the end of the year on the x axis I have distanced from this quenched and and then I here I have BA diameter so 4 what we usually want to have In indeed there the engineering steel products we want to have a 50 percent of Martin side at the center of the ball the relatively normal situation that's if that's the case you wondering why I'm focusing on 50 % and not 100 percent usually you you try to achieve you know hard out there said the surface and at a much more ductile and tougher center which consists of about 50 per cent mark OK so sources said that half of my property -dash Ainge corresponds to something slightly larger than the mill centimeter OK so now if I do an ideal quench yes this corresponds to a bar yes In of but slightly larger than 8 centimeters 0 3 .period complied inches yes bar I can but before I quench the outer surface with the jet of water has it that will be at 3 10 . 5 inch diameter bar that I can have that will have a 50 percent of Morton site in the center however if I cool not but for reasons of cracking and shape distortion I'm cool with oil instead the cooling rates will be much smaller yes yeah I still want a bar which 50 per cent in the middle of OK how large the diameter will the diameter of the yes well it will not be I 8 centimeter diameter bar but it'll be a little bit less than 4 a half the diameter book remember yes this is a function of the composition of the suspension of the composition the of this guy here In order to have 50 cent of market such I can very very large very very large distances from quenched and it's also very large BA diameters I think quench very large bar diameters even if I quench very moderately in oil yes note let's compare now with they the unalloyed steel that we had 2 thousand 40 this this was the the John many hardness profile but I can see here have to make where I have 50 per cent of Martin site has that is here at this very low thickness yes very very cold I'm very close to the quenched and has so now I I use this data on this point here this point here is the same as this .period has say I quench would even ideal quench you can see that the thickness that the diameter will be less than 2 centimeter or even even much less if I do if I do very moderate quenching with oil so I cannot there many products I will not be able to make with this deal yes because I will never have enough hardness In the bar so thousand 42 is is not a hardening and are harder ball steel and you'll never see anything being made with this steel this typical
products the there are alternative ways in which you can find ability data presented for instance that you don't necessarily have to have Rockwell data you can have for instance hardness Vickers hardness measurements instead and indeed access here instead of having for instance a distance what people the harder part ability data that they presented the maybe Vickers started as a function of what's called the long Kate 8 /slash 5 years what would does that mean this means T 8 the love of the 8th 50 means the lot of data cooling of the time In the temperature range of 800 to 500 degrees C. From office for the time it takes call from 800 to 500 degrees C so the log of this this time is actually 8 measure Of the cooling rate when this time is short it's a Hi cooling rates if this time is long it's a local English as and as a consequence we can see that's hardest data will go From too as this time increases why do people choose 802 500 well that's because for most feels that's the range where you have the the transformations of occur so is steel yes bonds which is very hard in a bowl yes will have 8 of its skirt that looks like this look that means even at low cooling rates that low calling rates I know I have a high hardness as but elements which and have less carbon for instance or have less allying elements who are not as hard a ball Will will have S curves that look like this the data look will look different when you use it differently also and in practice but it's equivalent to this job we approach the usually engineering steels if you want to use them you you need to have pardon ability data available which is Newsweek published but by the company that makes these engineering steels and there also ways in which yes you can do some calculations yourself let's go back 2
this previous Graf here this
remember that's we are trying to determine the diameter yes at the bar where we would get 50 per cent of Martin site in the center In the case of ideal Kulik yeah this particular a diameter is called the ideal diameter hands that's the ideal this this endit the people tennis
but determined what this the it is the that maximum diameter for 50 per cent mark inside at the center in the case of ideal quench conditions ideal quench conditions are defined as do the bar at the surface the temperature at the surface of the steel is equal to the the temperature of the coolant you using basically water at room temperature this and so they've come up with a formal minister which is the following tip diameter which is a function of see Austin Irene size and the severity Of the cooling this is the same this is a tabulated value its tabulated on the basis of a lots of experiments in which you have to accept and then there are factors factors which are a function of the composition and so for instance if I have a steel composition has certain steel composition group the grain size carbon content but and this is just an example here this would be 14 years and then have these parameters which are a function of the composition and I find an ideal dynamic look at end what does this mean instead if you a manufacturer all crankshafts for instance for cars and you so you could of course this steelmaker doesn't doesn't sell you crankshaft steelmakers sells you bars and you can do with it what you want dance but when you purchase the bars you need to specify viii composition not because you like best but because you want to make sure that when you do thermal treatment of you crankshafts this 50 per cent of Martin site in the center yes so certain the companies will when they orders steals engineers said they will also specified what the DI has to be yes so did with company does not only have to say did a specific chemical composition but the chemical composition has to give that guarantee the DTI value yes he may crankshaft 4 for instance big Marine motorists yes there much larger and you will have to be on the composition will have to be just so that you can make sure it's hard enough and strong enough it has enough Martin site at 2 cent to it's just of just couldn't Judas quickly this method is developed by Procol Grossman some time ago and that's it's also known as Grossman Hardin ability prediction method yes and it's important and then use and widely used to specify compositions that's so so remember we want to determine 2 factors in the eyes ears and then you have to have the seat that in order to determine the I need to 1st service parameter DEC but in the sea is based is function of carbon content Austinite grain size and and factors for multiple elements just say I have an example here is Steelwood . 3 carbon 1 . 1 % manganese .period for Silicon . 4 chrome and .period the 3 molybdenum and has a grain size of sex which is 40 so much so that all this is that this is the grass that you would use to determine from the sea or in this case it's called the icy but that this is the CIA to you may want to change this this is the DEC in the previous formal OK so what do I get but what is the carbon content . 3 What my AST M that sex means that this related to the grain size so I used the 6 the curve sex yeah this and and that's basically it I'm fine I read off the ground 14 this OK and then the outlying elements usually allow lighting element was will slow down the kind that exposed many decomposition reactions very often because when I have a decomposition reaction these elements need to change planes for instance they need partition to the Austin or they need to partition to defer a little slow down the kind that Texas has so right of these factors again this is not based on any theory it's is based on a lot of measurements and and then empirical facts after data to these measurements so sigh friends have 1 per cent means what is this factor here for manganese 1 presenter manganese I find a manganese curves and the factories to point something the point is the same for Silicon etc. and I find that this ideal diamond so what just what is it and what does it mean if I if I have this composition a bomb of 67 the millimeter will have 50 per cent of Martin site at its core guaranteed years after an ideal quench but if I have a normal ideal quenched With the pH value of for instance .period 4 . 5 4 and because I using oil this diameter will be smaller and the about this particular case 38 mm but that may be enough OK get but the steelmaker the provider of this deal it has to give compositions that will guarantee this the a value well right is an
example here so if if we have a non ideal quenched so age instead of using the water sprays yes right on the surface we used oil for instance and then saved the oil is a circulating oil the oil is not this not still but it's about whether some turbulence and circulating so my this is the diameter of the body now but isn't I'm going to be it's it's not 67 anymore but it's reduced to about 3 just because I'm using oil from severity is different OK and again nothing changes on the XK already X scale because the skill for instance and particularly since Johnny the results of the job right but now that the important if you ever get this not much research and engineering steels are acheived 1 of the reasons is of course because of the group like Posco hasn't really produced lots of engineering steels they know produce bars but it's not a big fan of the world is sizable production but it's not a huge amount of production in that area that tend to produce a rather standard rates is not much research in this area but I know people who are into engineering steel research they Obara steals in particular in the world you know have been working on improving this gruesome methods so and these are some of the the latest the grass that are being used to To determine these multiplying factors worse carbon and 4 father elements and that they may be slightly different than the original ones in the Grossman and it's important that it is also combinations of following elements some allying elements have a big impact on the the multiplying factors certain balloting for instance bore boron has this is the so-called boron factored the boron multiplying factor it is if there it it's between 3 2 3 and a half so let's go back to the To some yeah
here you have multiplying factors and you can see here so in this range here what did not many elements that have high 3rd multiplying factors the molybdenum is what molybdenum use is is indeed a annihilating element is still locked in engineering steels chromium manganese Ore can the sweet elements Nicole nothing really important but the other thing it's important in order to have large effects malt for chromium you will have to add 3rd Hi contents 1 . 2 2 per cent for molybdenum around 1 person has to have a pronounced effects not so it's the borrower moreover is already very efficient at extremely low contents like 20 ppm that's very very however and and the reason is very simple because In the Austinite boron segregates to grew grain boundaries this is also my grain boundary boron atoms sit here and when they do that they prevent remember the winner of the nite transforms far-right when Austinite entrances to the status is noble for an Austinite transforms to override the far-right forms at the grain boundaries of Allston that's where it forms a and and an end the far-right grains and Grohl basically there is no far-right formed in a wee crystallized Austin if we had Borel wants suppresses suppresses variety nuclear nations so far nuclear nations of variety suppressed what does it mean when you suppress the formation of a new phase you basically the seeker this is moving backwards this move to the right and so you make this deal very hard about with very small amounts of board however however when you add carbon this very high hard ability of decreases all yes and for instance if you have about . 8 common dissident means when the Steelers when the Steelers per letter the multiplying factor is 1 so that means the board has no effect right In case of certain what's what's the reason for the reason is because when you add ,comma carbon and boron competes for these grain boundary sites segregation sites and so if you have enough carbon the borrower will be replaced my carbon in the grains grade boundaries and so you will again allow far-right formation at the grain boundaries and the effective or on the hardening effect of Borel will disappear the very careful here when in Europe adding elements some elements may neutralize the effects of the others so never had a lot of boron in steel that contains a lot of cars because you may as well not have fought for reasons of their own hard ability right well let's let's have a look at some of them Holly uh can make steals by playing around with them these the kinetics of the transformation so remember we will look at so when when we transform steals we have the seekers for the nuclear nations and growth type of transformation and then the horizontal lines for the thermal time independent transformation for decomposition to Martin's so let's look at that so these courage where they are yes and how their shape is composition depend and these parallel lines their position is composition depends so let's have a look at if we do the the 1st cycle yes 300 we call to 350 very quickly and hold for 10 thousand seconds that we faced inimical to root out just what do we get 315 here after 10 seconds the transformation starts transformation is the low this knows and we know that very nite yes we also know that if we keep at very long temperatures but very long time said excuse me at temperature we get Sparrow died roll eyes and so at 50 but the Internet 100 seconds its 50 percent transport little about 200 seconds we get 100 the central of and nothing much happens yes still we cool down because down to room temperature so but we pass M S & M F but does anything change no because the transfer the the Microsoft is fully transformed already and this doesn't really have any meaning that this is the MicroStrategy get fully Benedict still another cycle 250 100 seconds and then we cool to room temperature we cool down to 250 hold that for 200 seconds and then cool 2 room tempted to what happens here while really nothing happens to the Austinite at this point nothing which is there all this very very unstable is of very large driving force for transformation but but where such low temperatures that is not even if we form small nuclei is no growth of I nepotistic would be very nice because of there's nothing really happening as we say Austinite is meant stable 100 2nd we cool down and then will look for fully Martin citic Mike rastructure in this thing and there's no reason to make more complex because of thermal treatment Sorensen cycle 3 you cool to 360 stay there at 10 seconds cool to 400 hold thousand seconds and then cool to room temperature .period you go here also tonight if you transform pretend seconds I will 50 % will be Our like this because I had reached a 50 percent here so now I'm left with 50 % Austinite I cool down and I do the transformation it's very nite transformations and when I cool down so I will have 50 who runs a room tempted again the fact that I passed M S & M F temperature has no effect because of the transformation is finished and they get 50 cent and 50 % now you
may think this is all academic and it's all very funny and easy to understand but I know but it's actually used in practice as and our furnaces an alliance that produce large amounts of steals 1 of those special steel Mike rastructure this way France is this is a line here in industrial lighting which is designed by the famous company in German company there there'll over the world but it's Gold Edna the very famous furnace builder and it's it for the the and thermal treatment of narrow strip no if you wonder what it was a narrow strip is art is a product of the narrow this deal the obviously have been she's like at 1 time the product is narrow Watson a narrow strip product if you work in gardening and many tools or narrow strip products for instance also solves is based the narrowest strip products so songs Woodbridge for instance made with the line like that's Mike rastructure so you come in with them the straps so users of coral the narrow strips it's a small strip long strips of still work but and so you uncorrelated and you get the strips that move into this this machine here and this machine is basically
being allows you to do thermal treatment of narrow strip friends and you can set it up To make different types of heat treatments france anything you can think of is in in principle possible to friends of this as the structure to do us temporary thus tempering is that the word that's often used for performed for Benedict transformation so you have to have an Alstom bring furnace and then you do a liquid metal quench liquid metal quenches off is very interesting way to quench a material at high temperature so if you want to if I ask you what you need to quench a steel but you need to quench it at room temperature you'll say Well I take I go to the said make put some water in it at room temperature control my steel in their rights since it's going to cool too room temperature but if I you that you wanted to quench it too 400 degrees C then you say Well I can't use water right because cause I would want to have vapor and my water would be gone all right you say Well I could make a furnace maybe for at 400 degrees C that would be a good idea but you'd have to make sure it's home watching is another way to do it system use liquid salts themselves but they're very aggressive but you can also use liquid metals like led by new melted led as this is used as a European heated up it doesn't evaporate and it's very flexible so you can use liquid metals liquid metal salts are used very often to do 1 thing Ferguson you go there you can use a metal quench but until you get a nice isothermal temperature that's that's the important thing right you want to perhaps the way you I just described it nice size of thermal treatments added to control those leveling furnace to get you know this trip at the right temperature and then you have a tempering surfer furnace and then finally pulled the strip and then you coil it up again of this will allow you to the Allston ties the 1st segment has the you you cool down to the quench keep the temperature and then you get you to the final Jack Gould Inc you can change it you can maybe you want to make Mark Martin site and maybe you want to often with Martin cited the MicroStrategy is very hard you want to make it slightly more ductile by precipitating some of the cars and its carbon as Carbide's so you do you temper the Martin again that this will use this same line except the parts have been changed and you have to proselytize liquid metal quench strip cooler a leveling surface at furnace tempering furnace jet cooling and you coral destruct which you do here again you Austin entice material you quench its then you need to the nice genius temperature you reheated in day tempering furnace yes and then you Jed Callen because you can do this ,comma strip continuously so this is an example of just example was for heat treatment of the strip I Boris deals can also be but treated for instance here you quenched and tempered the special bar products as in this case would you see it as a bar product is basically a cylindrical rock was the new CU what happens the cylindrical rather has been made sense and now we're going to heat treated so we pass it through the series of inducted conductors which to the induction heating you can see the box it's very high temperature and then we pass it through this this and this is a box here this box here and in this box this is in the interior you see quenching sprays and the quench the the 2 room temperature and then the buyer passes through the 2nd set induction induction heaters now you don't see the bark of being a bright yellow yes because the quenching temperature is typically depending on the application will be 3 400 degrees C I'm so so you you you pass it to a 2nd that set of the inductees to tampering and any final question you can this peace process or not a limited to just she narrow sheet you can apply just to bars well I'm going to skip this just seconds he has an even
extremely large for checks are we are heat-treated inferences this is of the thing got here and in here it's being forged in an open for Dinkins is a huge forging yes forging here eventually you make this I think it's so it's a it's a new turbine shaft here and this is also heat
treated and you can see here than
in the lead the the heat treatment you see it is a very large shaft is being put in in a quenching Basque yes 2 2 2 harden basically now they let me just
finish this so we don't know that the problem with many heat treatments is that there a very complex and heating cooling and so on and lots of us are fixated obsessed by gate by thinking that strength you need to have complex Mike rastructure it's not always like this for instance we were talking about
crankshafts In the
past many crankshafts used to be made with the pretty complex the so-called conventional quench and tampering methods so you would would forge the the State the Department you start with a boxing and we have to forced to shave yes and then you would do quenching you would have to temper at the seed treatments would result in some distortion so you would have to the correct to shape there's and do some stress relief yes nowadays so you can imagine how many furnaces this means yes and how complex the whole operation is nowadays we don't use the steals anymore for a large part we use of coal vanadium micro alloyed variety was lights to and the the Treasury's sample which is hot forged material and then do controlled cooling that's it very simple when you get very good properties so I and that's also part of the unit doing steel researcher products research in general it doesn't mean you know making things very difficult and very complex it may mean very often but when you're the successful in innovation means being able to find solutions that are very elegant and simple this is 1 of these so these seals can be heartened by simple controlled air cooling there's there's no additional heat treatment required except the ones that you always have to do matter related to Cobb arising where you you used to pardon the surface and ended the reason why you'd you'd say Well how can you do soft coolings young hard materials you get equivalent strength as as you know what you have to do previously with Martin such while basically because you microbiologist you vanadium and some higher nitrogen content and that forms precipitation hardening of particles and these are very very effective too that high stress and you can see here but the amount of vanadium the theory is that you need we're not talking about future months either to the impact of this the addition of vanadium which is not cheap following elements is is relatively mild because you know you have much less complex process in which she proposed and a very slight increase in the alloy products by as a result of the definitive book it so you know complex it's important to understand the complex of phase diagrams and kinetics of transporation but it doesn't necessarily mean that you know when you design still you have to make it necessarily difficult sometimes simple and elegant solutions are used in the industry OK so undelivered overturned thank you for your patience with them so we'll see each other on Thursday but we still around just so you know we we start with the No 10 to 15 minutes quarters and then for the next week's from then onwards will repeat this every week I can tell you that yes also have a look at at the the class because will cost you knew or corrected flights because the
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Metadaten

Formale Metadaten

Titel Modern Steel Products (2015) - lecture 3
Serientitel Modern Steel Products
Teil 3 (2015)
Anzahl der Teile 31
Autor Cooman, Bruno C. de
Lizenz CC-Namensnennung 3.0 Unported:
Sie dürfen das Werk bzw. den Inhalt zu jedem legalen Zweck nutzen, verändern und in unveränderter oder veränderter Form vervielfältigen, verbreiten und öffentlich zugänglich machen, sofern Sie den Namen des Autors/Rechteinhabers in der von ihm festgelegten Weise nennen.
DOI 10.5446/18350
Herausgeber University of Cambridge
Erscheinungsjahr 2015
Sprache Englisch

Inhaltliche Metadaten

Fachgebiet Technik
Abstract A series of lectures on steels, given by Professor Bruno de Cooman, Graduate Institute of Ferrous Technology (GIFT), POSTECH, Republic of Korea

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