Modern Steel Products (2014) - Formable steels: lecture 22

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Video in TIB AV-Portal: Modern Steel Products (2014) - Formable steels: lecture 22

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Modern Steel Products (2014) - Formable steels: lecture 22
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22 (2014)
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Professor de Cooman takes the topic of formable steels , in particular the TRIP steels and hot-press forming steels. Both the production and metallurgy of the alloys is described. This is a part of a course of lectures given at the Graduate Institute of Ferrous Technology, POSTECH, Republic of Korea.
Keywords The Graduate Institute of Ferrous Technology (GIFT)

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I we put these lectures on You Tube also so if if if there is no sound In London the very unhappy so so why is it that the on and constructive solid keep it at 400 degrees C and you don't get any Carbide's so well so remember 1st of all I you start with the into critical annealing so all . 2 per cent and you do it a critical annealing and the way you do it with our troops steals is you a meal at a higher temperature than dual face deals In order to get more the Boston you get this Boston contest and you cool down too so you go like this 0 . 2 per cent this year and ended the began a face you have high temperature has . 3 I think of you have to look at the faces let's have faced I grew up on the screen that would be helpful In the you know what this is the
current troops mouse in the
world what is next to the so we talked
about . 3 2 points for carbon and of course if I would call this down at this time I I would good DMS temperature and good amassed temperature also and I would basically get a dual phase microfracture with 50 per cent of markets said but that's not what we do we keep the temperature at this point now at the and so that's about 400 increasing typically and so there we this Austinite tonight will undergo Abe a major transformation and it's urbanity transformation that does not include Carbide formation and the reason why is the presence of silicon and remember when we had the introductory lectures assessed silicon suppresses Carbide formation and the reasons for that you can of the number of reasons but you can pretty much explain it by saying that well 1 of the 2 reasons 1st silicon is not soluble in this human tide and the 2nd reason is the silicon has increases the activity of carbon infra against anyone let's just say we know that Silicon suppresses Carbide so what happens then is instead of staying here the carbon content will during the transformation will increase and yes to a specific point as we know it and I said that .period is that T 0 ports because he's 0 .period tease you giving you a carbon content it's far more than 1 per cent and so the Austinite that you have at at time which is very enriched in carbon will will have an MS temperature below room temperature so when you cool down nothing happens it doesn't transfer are so I will walk away does this happen well you have to remember that the phase diagram just behind the phase diagram there is something up there it is yeah and there is thermodynamic and then there are thermodynamic let's put it this way thermodynamic functions yes and his thermodynamic finds basically related to the stability of the forces that can occur in that system so in this case in this particular case during debate nite transformation I have 2 phases I have the right and I have Boston and case of the the and as the stability of a face is determined by its free energy and I know that's 1 thing and then the other thing you need to know is that our it's the free energy use is low it means that the faces is more stable on the lower doses it's a even more stable and if you have 2 phases and the system has to decide what to do it will To still lower face lower free energy state so fought for any phase the the free energy is function of 2 parameters the temperature as the composition but so you have many elements associated with so at it particularly temperature at 400 degrees C that means it will have a free energy forgery the right things and for the Austinite face that will depend on the composition and it looks like you might know could calculate this but the basically looks like this well it's a function of of the system would be free energies functions and this is the carbon content of the have to imagine this this lies behind them and so this point here which we call where did she of gamma and energy of Alpha all are the same composition at which they are the same as I am at 400 degrees C at
steps like this is Steve 0 at another temperature at another temperature and GE being function of the this to 0 .period will be somewhere up yes but I it's nice to you can actually draw this 2 0 line of phase diagram as it lies here somewhere like that and what you have to imagine that during the nite Carbide free B'nai transformation is that there is would you thinking of a face I ground where there's no carbon yes there is no carbon it was and I'm basically doing using this material this this steel list this gamma phase that bring it at this temperature has and there's no Carbide formation was then this system will want to have this carbon content in the far and this carbon content in the Austin I guess but it doesn't and the reason is that the following so the we have a carbon content here that the original Carbon that would be around 4 . 3 to 0 . 4 Carver that's disappointing so we're here and so at this stage we can see that the the free energy of gamma is larger than the free energy of Ferris said so if I have this gamma phase yes I will start to make there and it's at low temperatures yes so it's a is a of the way the the transformation happens in this particular case is Benedict transformation so it works in little steps you formed small units has for small units and because the Blairites variety looks a little bit like Martin side on the finer from say of smaller units units and then I come to think of that when I make this unit there the strain energy has and the kind of stops 12 what happens then is the carbon content when has the the carbon will leave this fair I guess we will not form Carbide again it's essential that there is not so much so that Carbide's are not for because otherwise you will get standard they 9 so the carbon is expelled yes and you go into Boston it goes into the surrounding of so no OK so now instead of having that this 0 . 3 0 . 4 carbon here yes I have slightly higher carbon and so at 5 I had this Boston yes and again the free energy of this Austinite is larger than that of far-right yes and so I can fall continued to form terror and far-right will expel carbon yeah this will go on this will go on and progressively the Austinite will increase in eventually you'll reach this city 0 . in composition so can you go beyond this point can you go beyond this point can you increase the carbon content further and there no no why because if you would do this yes the Austinite is more stable than the fare so so it's stops here but it is also my doesn't transform fully to 2 the right In order to bring Teixeira I promise and because it it just keeps on getting the carbon From the the transforming there then you get justice huge
amount of carbon in these in Austinite and its readers how much How much Austin of course because during the May transformation of course I start with this gamma In 2 critically in gamma and I go to retainant gamma plus they Teixeira said so where this will go into the structure where I will have as I showed you you have Benedict far-right and in between you have retained Austin and how much is last how much volume Percent of reading Austinite can you expect all anywhere depending on the carbon content and composition of course 10 to 15 per cent and so on so we now have a Microsoft rupture which looks schematically like this so I have Fahrenheit the you I have
fairer elsewhere I have been in Teixeira said Elf of being in and have Austin begin out why is this helpful to have this I'm also tonight in the MicroStrategy fall what you want to happen it is that the In the Austinite yes In the Austinite when I apply stress and the material the forms yes I want to have this Austinite trends for To Martin site this and I want it to happen by what is called strain induced transformation defamation induced transformation what is defamation induce transformation it means that 1st the Austinite creates dislocations yes and these dislocations these this location interactions create nuclei for Martin side this and the more strain the more I create new nuclei for Martin sites and what happens every time Austinite is transformed to Martin society it's replaced by a much stronger phase of ornaments and 2nd a phase that has a larger that takes in a larger volume in the face it replaces so suppression of madam when you suppress snacking it means you have higher uniform along nation or in other words you have more strain hardening stance and that's perfect thing for any material because you extend plasticity at the same time you increase stress look at that it's a very tricky 1 thing to achieve this strain induced plasticity and I just want to say a few words about this year's so when I mean you know from your undergraduate classes then 1st medal a or material science said if this is a temperature scale yes and if I have some kind of Austinite there is this temperature which we recalled an ax yes take Austinite I quench should to be low MS what do I get I get Martin side and that but there are many other ways you can make Martin said With the same material with the same face this Martin sites called a thermal Martin side there's the thermal Martins it's boring because the driving force thermodynamic driving force for to transform for transformation to far-right has become very high as and you can show that in many steals this transformation is not time dependent and that's why we call it a thermal and don't ask me to explain it because I I think because this would not be the thermal it should be time independent or whatever but anyway it's called a thermal margins are good however in in the case of Austinite at room temperature about there is also but MPs segment temperature this and there's also a and D temperature yes that the defining Martin site transformation 1st of all let's do and the temperature yes and the temperature is a temperature above which whatever you do to the Austin In terms of defamation a adding stresses that it will never transformed yeah so above and the yes Austinite is stable so I sue question it's for stainless steels for instance Austin epic stainless steels what is really important he amassed temperature or and the temperature and the temperature much more important because you have Austinite at room temperature yes you have a very low MS temperature but what happens when you deformity also and you don't want Martin site to occur that Andy is very important that you have pictured that Md if lower than room temperature so if you don't get more in this case we want Martin site yes and we want Martin site during deformation if we don't want Martin side when we applies just stress but and this is the miss and ass temperature the MS temperatures the temperature that defines the range where you have stress induced Martin and arrange where you have strain induced Mark inside and for trips deals you want to have a room temperature has to be in this range of what is stress induced Martin well it's very simple when you have the phrase I just told you that the free energy of a face is a function of temperature and composition it's also influenced by stress right because when I knew apply a stress elastic stress on the material but add energy so if this is G as a function of tea for a concert for competition constantly a single competitiveness that I have something like this no and I say this would be free energy of gamma if I add stress must stress elastic stresses men free energy goes up and I remember higher free energy means less stability so I make it easier for the material to transport and there's no defamation involves no plastic deformation only elastic deformation so that means if I'd be fine the former material here I stresses elastically Kabul I get Martin site because I don't want this I want this this strengthening of the material and the expansion of the material to happen when I'm doing the defamation Prince when I pressed pressed pressing or when I that typically a formations yes I want to have the deed strength increases so I want to have room temperature in this range where you have strained assisted transformation right so
I would add the important elements again the composition of the steals very very I would wish with saline and not know not many elements in and said the main elements there is carbon it's slightly higher than in the case of the peace deals of between 0 . 1 and 0 . 2 it will have an impact on the face distribution on the retained Austinite stability it will also be the main hardening element for Martin side when I make the Marcum site and and then it may have some important impacts that if I have played type Martin side it would be reduced to the year toughness and of course because I have a relatively high the carbon content it may also impact the it does impact to carbon equivalent and impact on the weld ability of these materials but that's not a very and all of very big issue if you take care of them Due to the right of selecting the right welding conditions the manganese is an Austinite stabilizer here has its strengths is the far-rightist suppresses perlite formations of the main things and here have a very important for the trips this the addition of silicon aluminum and phosphorus and in particular silicon yes In contrast to the DP steals here you add silicon 2 suppress Suman tight formation of aluminum and phosphors do this have also this effect you can also use aluminum and phosphorus to suppress Simone tight formation near or right stabilizer there accelerate verite formation increased activity of carbon they also very good at strengthening variety I and there may be some editions of chrome and Molly sometimes but suppressed perlite formation but not the
commonly it added to cold rolled trips steals now I can we make trips steals volume controlling yes no problem so this year this diagram here holds for cold-rolled yes cold-rolled where the starting material here With this cold-rolled strip steel I am and you do but and when you start the 2 process the material in you can do the MicroStrategy initial Microsoft options is fair right no reason to make To start with the the trips you might restrict for you do enter critical annealing and then the B'nai transformation in your continues the annealing line when you make the attracts steel In a hot strip mill so you again you start from your Austinite which comes out of the tandem finishing mill at around 800 to 900 deg C and then you keep the temperature is a constant and you do this To make yes and and rich but the Austinite in carbon during the Proehl you take toward far-right transformation and then you cool down 2 the coiling temperature in In this case the court temperature is above the amassed temperature yeah but amassed temperature end and so you do the that the transformation of so the here this Austinite here transforms too retained Austinite plus Bay Night Nurse at 400 degrees C what happens when I'm making the retained Austinite yes it at this stage is the MS temperature decreases of course that's because I and rich by added the the carbon content in the Austinite goes from . 4 2 1 . 2 so as to gradually there is a decrease in the amassed temperature and you do this that the B'nai transformation in the court the coiled material and you get and when you go to room temperature of course room temperature Europe above temperature and you don't have to they Martin site formation you are left with reading Austin Tex because
so this is the same for the I just explained when you do continuous annealing this is the reading the data into critical Austinite so you have to cool it fast enough to 400 degrees C so you avoid the far-right formation when you do the B'nai transformation yes it'll start here the amassed temperatures starts to drop because I add carbon to the Austinite during the B'nai transformation and the transformations stops when the transformation is incomplete they want when you've reached the T 0 like and then you can cool down because EMS temperature is very much lower than room temperature so again if we
look at the fair the structure originally will consist of far-right fair Riddick Bay nights yes and retained Austin yes and that's the residual Austin K and you can see the residual Austinite strength is less than 600 make Pascal yield strength here and these are destroying values 4 contribution to strength of benign and the contributions to the strength of the yen and you can see for instance well Knight is a little bit stronger than the fair I because it's got lots more dislocations in it transformation dissipated and it's got a small elapsed size than the group the grain size etc. so but it's it's not the hugely very strong very much stronger than the than regular fare so what happens is that when you try this residual Austinite is this changed into Martin site during the transformation and it's a high-carbon Martin site 1 . 2 per cent of carbon so you looking at the 2 thousand 500 mega Pascal the the increase in local struck him so are trips when when we have the trip a fact that the material which without the trip effect would be Of course this particular example here of 6 80 mega Pascal the defamation which gives me the transformation to market such dissimilar material which the strength increase close to 900 made up of Of course you don't get this huge amount of of strengthening y because it's there retain also is only 10 per cent Of the microscope right so so you you will have an increase of about 250 make a basket but best so that's that's about which which we
calculate so the very important here is the fact that the strain hardening and when we strain hardening of France's the highest-ranked IF steel that's what we see His dad so you have the strain hardening this after 5 per cent of defamation yes the and value reaches a maximum as of about 4 . 22 years and then you got a continues decreasing Of the and value yeah if you do the same thing for the 8 but the trip steel for trips you see that you have a sustained strain hardening yes and can reach up to value .period break before you get in reduction in US and so on but the line where the this this this strain yes is equal to this derivative here India um this call the instantaneous strain hardening you can see where they intersect that gives me the uniform innovation so I see an increase in uniform along as a result of this drop the trip
effects now and you have to be aware of this this whether or not it works how well it works depends very much on the steel you have them so the the choice of the chemistry of the steel of a trench still it depends on what you want to further we already discussed that with we said what we want to have strain induced the of Martin site you and we want the transformation has to be sprayed Over the difference the defamation packed the answer would we don't want to have a lot of transformation very early on in the deformation or very late in the deformation so for instance you can see here is the kind that takes the amount of bottom side transformation as a function of strength and using different types of trips to the princess trips deals which only have silicone yes that transformed relatively early in the strain trips deals where you have replaced part of the silicon with aluminum and phosphorus have emerged more spread out the deformation of Soria transformation kind at 6 so we will want to this diagram I would like to too much details so but let's have a look
at some of the trip grades here so but do you looking at material switch which can easily achieve close to and 700 or 800 mega Pascal and tensile strength and have reasonable along gations minimum of 23 per cent in and also but they turned out to be pretty good in terms of big hardening against so Is there anything we can all we can do 2 the built on this kind of work alloys system but now why not if they being a transformation gives me so much strength 1 not forget about the far-right face altogether and make a Benedict's entirely Benedict with some retained Austin that from the steals success and we call them Benedict states that's not yet and so that for instance if you look at the hot-rolled fully Benedick still in doubt In the hot rolling In the in the hot strip mill hot-rolled material and then you cool down quickly as you don't need to make far-right in you cool down quickly to debate a nite transformation temperature yes In the course and during this transformation and he amassed temperature will decrease because enriching also life with carbon and then when I cool down I get carbon-free being I guess and it's stronger then the star I can also make 8 far-right Bay nite steel mills where I can control on the amount of yes so for instance here it's it's and it's very similar to what you would make in In steel the trip steel except it's got more Barry nite in it so after the hot rolling I do it verite transformation yes and then a day-night transformation In
this example here of 1 of these verite Bay nights steals you see very very fine this is 10 microns remember that engages a steals ah grain size is this less than 10 microns but more than 5 microns and you can see that much of this Mike rastructure the far-right even a smaller units to have very in these variety they nite the structure very fine far 1
of the reasons why we're
interested in this very fine my press structure is
is form ability it turns out that In trips steals and indeed peace deal because we form because it is in comparison to Friday night's 3 steals the microsurgery is a little bit course yes the performance of these materials the test called whole expansion where you basically have to be pressed part which as a whole and when you press it again the whole expense yes but we see that trip seals and you will face deals will cracked at an earlier stage then the far-right the nightstick States that's 1 of 1 of the reasons why Friday-night steals are being used in certain applications listen example here of they might steel 1 of the things you'll see here it is it is still looks but a little bit like a trip seal in terms of the processing but very important it's it's it's a low-carbon low-carbon steel and the other thing is the refinement that you get From of the far-right yes is actually did you too micro alloys and here's some properties With the 600 make a Pascal a very large totally longer Asians this is
an example of a complex face steel grade it's deserved highest bid actually very similar to variety the nights deals but that the mikes a bit more complex in the sense that in addition to the small far-right grain size and being nite it also contains Martin site and retained Austin it is an example here of a 900 it and because there is Martin side and retained most nights of democracy you get larger the strengths OK nite close to 900 make pass complex phase or CP Great Falls and and they're already standardized are up to 9 make Pascoe
nowadays this trend true to go beyond the a 980 make a Pascal's go beyond the bigger Pascal has resulted in the development of grades which are ultrahigh stress to the which are more than but thousands make Alaska 1500 and there's a lot of active research in the development of 2000 make Pascal grades that can in some way be formed 1 of the ways very creative ways in which you can increase the strength is by the clinch hardening the war and in using press hardening steel so the idea here is to if we have an ultra high strength steel warden and the capacity of stress it becomes increasingly hard to press these materials obviously 1 bigger Pascal material press this you eat you need more power in your press you will damage your press much more the forces will be higher and what's more there is this a phenomenon called elastic spring back you press the part that's very high strength when you do this to you generate very high internal stresses and the part when you removed did the dies the people that the part literally springs back and this can lead to curvature Of the part it can let lead to all kinds of problems related to the dimensions of the parts and they mention control for instance automotive industry is extremely important you know when you cannot have when when you make a part it's got to have the exact dimensions and so if there is some elastic distortions due to spring back you know you will have to do it big-headed basically so 1 of the ways you can solve this is the press hardening steel or quench hardening steals note I think the material you make blanks yes are you form a blank trimming presses and anew heat material he he commits went ahead as this material look like originally bullets and very simple far-right but like a structure so I no the property of the starting my prescription are here less than 600 make a Pascal the longest about 20 we heated up however yes to 900 deg C we all ties in other words so this microscopic turns into homogeneous Austinite and then that's in the heating furnace and that we do we press for we press formed this Austin but we press foreman in water cooled the dice so what happens you bring the material in you press former Austinite yes as you continue holding it in the press the material was start cooling down yes and the 2 did calling rates pretty high yes and you'll learn to make markets so this structure is turned into the structure and you know of course that the the system Latham Arkansas depending on the carbon content I can get anywhere from 1200 mega Pascal to 1500 mega Pascal and even beyond the so you but that's supposed to make this it is so severe that the properties at 900 of poverty soft used material has utensil strength is less than 300 ended a long gations fabulous 50 40 to 50 no problems too during this In 2 Austinite at high temperature and then turned that into Martin side left Martin site that the room temperature and in your that
what it is this material here we used so for press hardening steel we used material that contains the that's carbon manganese and boron steel yes why do we add boron well to make this steel harder but yes to suppress far-right formation another important point about this steel is that because you want to have the borrower uh effectively working as pardon ability agent you add Titaniums Titaniums because Titaniums forms Titaniums nitrite yes and there is no 0 Borel nitrite formations that's 1 of the problems and we've discussed this in the past is that when you have the boron and borrowing to steal it will usually scavenge that is buying 2 of which nitrogen theirs instead of staying in solution and this can be avoided by addition of fighting which then protects as it were the uh boron additions you've made there more an
interesting developments in the direction of making former Hi and ultrahigh carbon steals 1 of the very interesting concepts that is being developed and then developed in the past couple of years which called Quentin partitioning steel Q and peace deals if union people processing of steel involves the following idea and then you can carry this out in a continuous annealing line if it's equipped for it so what would you do with the idea is a clever idea and it's also based on the idea of trying to introduce retained Austinite in a Microsoft trucks and in particular in the Martin citic Mike rastructure because when I quench from high temperature To low-temperature I just make laugh Martin carbon is in the suit supersaturated solution and and I don't have that the trip effect or don't have is the trip affects the plasticity enhancing mechanism so let's look at what this Quentin partitioning involves you'd see also the ties your material and it's a 1st step is quenching another clever thing is In this processing is that you stop In the MS MF range please stop here because the transformation is a thermal yes the temperature at which you chose to do the transformation has the temperature will also define the amount of Austin you have them I stop here I quench here I will have some Martin side and some retail and Austin a so now what's the next step is you reheat this Mike rastructure and what happens is this year the market site which is supersaturated in carbon will now transfer the carbon into the adjacent Boston yes good and when this happens of course the MS temperature will drop it will drop so that when I cool down yes some of this retained Austinite to some of exists this Austinite hearing some of this Austinite here well these retail this winter so will not fully transformed to Martins and I'm left with a MicroStrategy it's Martin said with pockets of retained Boston not you you may
ask yourself while you know a of business mistake long times and everything will know it actually that you can
actually uh that the transfer also the carbon From the Martin site to the adjacent Austinite happens very quickly we're talking about a a matter of seconds and the reason why Is there because they're in this partially Martin said Mike restricted you have very small diffusion distances good for instance here if you look here you have a small laughter of Martin side and this is also the Nigerian you look at how long does it take To have almost no a lot of carbon transferred from the last To Austinite and you see here after 5 seconds 10 seconds 100 seconds here a lot of the carbon is already in the Austin over distances of the Order of I the tend to two-tenths of a micro and that's enough senior princes after the 500 seconds it's less than 10 minutes this is the profile Of the carbon in the Austin and the and the original profile starts of course with you can see most of the carbon just quickly so and at 100 seconds you're already here so and that's about 2 minutes the very quickly you get 1 the transfer of the carbon into the adjacent Boston there you can
calculate and then I want when you make the complex Mike rastructure is like this but things are more the physical melodies more complex and the and it turns out that there is an optimum temperature at which you should quite that's and typically it's for carbon steels at around 200 to 300 degrees C and how much of what is the maximum amount of reading also like you can achieve both around 20 per cent of defaulting have so and the chemistry of the scales not very complex against them of no carbon here this is typical composition comments Silicon very often because you don't want to against suppress Carbide formation and then in the properties are
are good here you see here if you and people says materials have the same strength the range as Martin said steals except you have a larger totally agents and again but remind you of the fact that these old ultrahigh strengths Greg Quentin partitioning offers you a a lot of strength and you don't gations form ability that's all better than the equivalent purely Mark acidic Blackmore septic system but nowadays
stealing she's discovered that working on Mike rastructure as can be very rewarding in terms of properties has instead of just focusing on chemistry and chemical compositions like the carbon content of manganese the content and of the new steals a coming into consideration was 1 of them is took steals yes and the beast which deals are all Semitic steel the not morph of it to the Austin addictive and you can see here what happens in it would still is as you the strain the material you looking here at the grain in the material is it's got some and kneeling twins yes which normal In Boston thick steals but when I strain it denies I look at the grain I can't see use a very sharp wines slip lines appearing and more restrained the more the grain is divided and subdivided into tinier and tinier than surrounded by twins 10 and so you know you can see this in in TM very much as what we see is that the strain we see a lot of stacking faults in the material when we start straining we which Rossiya dislocations being formed In addition to more of the stacking faults and eventually it around said 10 per cent when you look at the Microsoft the entire Microsoft is full of these very thin twins so what happens in a normal Mike rastructure the dislocation and you have this location source here dislocation loops are generated during plastic deformation as and so on and they run into grain boundaries and things like this and you get strengthening In the case of the so-so deep the mean free path mean free path and dislocations can travel will typically be of the order of the grain size and we know that making grain sizes smaller gives me strength so when you have what's called defamation twinning this phenomena that I just explained that his trainer material former Twins defamation 20 that my course structure will gradually be divided into smaller and smaller dimensions so the dislocations will have a smaller and smaller mean free paths it's sale I had a dynamic call patch effect yes I would strain material and the grain size would get smaller and smaller yes to the tensile strength gets higher and higher so that is the mechanism of strain hardening in these the states
10 again as I said I'm going
to have to stop here which is new types of development the yesterday than what is interesting of course is that thanks to dip their mother processing technology we can don't make the state In the past it was much more harder because you and that only batch annealing nowadays you can do continuous annealing and you can actually be quite complex thermal treatments which allow you to make these Microsoft ruptures In a relatively simple way and the reproducible way and using steel said are not highly alloyed or on terms of compositions are relatively
simple right let me
introduced the
subject we will be
discussing started to discuss next week what
next week not next week Thursday so if I'm correct
there is voting day on Wednesday tomorrow and on Friday's Memorial soul and there were no classes on these days from what I understand however is not holiday for us because we're meeting on Thursday because so we will have and sorry to say the quiz on Thursday can but let me
introduce the bill so this is way will will work its will to bar and wire products but you have to do is strip products and then will go into along products and and placed if we have enough time so what this is 1 of these very famous products from this category is rebar that's used for construction reinforcing cement construction I am really Will talk about of a lot it's
about and and in particular with will get lots of attention to Wiren Ronald and and and 5 products groups namely rebar tire cord gold heading quality steel spring steals and bearing steals in addition to free cutting off free machining still will discuss the the concepts behind the steals the and the compositions the processing and explaining why why certain choices are made because of the application so How does this
compare to that of the product we discussed we just finished discussing the hot-rolled and cold-rolled products for friends for a company like ample scope out in 2007 you see that cold-rolled and cultural products very very ill strongly represented bosses also Baker played producer but you can see here that of wire Ronald products are also very important to us that industrial and so that's why we will be talking about at the start of why Ronald and borrower starts in wire rod and before the wire rod and bar a mail in a continuous casting facility has usually combined with spectacle foreigners to make steals but not necessarily certainly if you have an integrated mill some of the the steals can come from my the U.S. did you but anyway you can use it in this technologies for wire and Rautenbach use continuous casting spells Of course you don't use slaps but you use multi strand Costas here if you looking at square billets and I didn't want to the 6 here 6 strands of casting material
very important In this type of field is the internal cleanliness of history however but you can see this here this and the the life as it were for wire as a function of the oxygen content in the steel and the oxygen content you have to see as a matter for the content of nonmetallic inclusions oxides that you can see that as we reduce the oxygen content and we have a tremendous increase was it's a log scale in the number of cycles these wires will survive and the trendiness 2 words to use of you know vacuum treatments use of the control of these nonmetallic very often when these wires break which would people actually find is a nonmetallic inclusions that causes structure and and because you have a Y years yes the impact of 81 small the inclusion is very important and the sheet In inclusion isn't known as the effect and is diluted but in a wire it's not even if there's only 1 that's where Albright and so very important here and it does have influence on the medal orgy of you know for instance in certain applications like spring steals where you do fatigue the material during its life on you you will avoid using aluminum killed steel you will specify silicon kilts deals to make sure that this type of nonmetallic inclusions aluminum type nonmetallic inclusions interfere with the young or reduced to 55 OK but will talk about this on Thursday after you folded tomorrow for the party of your choice thank you very much