Friction Stir Welding of Mild Steel-Tool Durability and Steel Microstructure

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Friction Stir Welding of Mild Steel-Tool Durability and Steel Microstructure
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Friction stirring of steel: APMS conference
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DebRoy, Tarashankar
Bhadeshia, Harry
De, A.
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A lecture given by Tarashankar DebRoy, at the Adventures in the Physical Metallurgy of Steels (APMS) conference held in Cambridge University. Mathematical modelling of the friction stir welding of steels. In previous work, we have established a scheme that exploits a combination of three-dimensional heat and mass flow models, together with fast calculation algorithms and damage accumulation models, to assess tool durability and define the domains of satisfactory tool life in the context of welding difficult aluminium alloys. We now apply this scheme to the friction stir welding of steel, and extend the calculations to cover consequences on the microstructure of the steel while optimizing tool life. This is the first model which covers both the processing parameters and the consequences on the physical metallurgy of the steel.
Bhadeshia, Harshad Kumar Dharamshi
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see but I want to acknowledge contributions cry my co-workers professor only double their from IIT Bombay and professor intermission the fiction style will it is not common
used for Stevens it's a very nice promises for joining soft allies like aluminum alloys and the problem
is with the tools 4 are willing upon lies the pools went out of the pool of freely in extreme cases and the cost of the 2
the main Mannheim also the main problem is that
ended by the high temperature and they Lappin heating cooling and and stresses on the 2 so here
is an example of what happens even far harder aluminum alloys like 7 poles and cities aluminum alloys or if
you putting some particles hot particles the pools where are our very opinion in extreme cases for stock and conditions they can't even failed catastrophic so
that is the that actually the major problem and many of the 4 steals the structure and properties of freaks and stuck with Stevens have not been studied antiquities
even for aluminum alloys and the fiction starting does not seem to to have an advantage compared to fusion welding in times of distress so and
member of aluminum alloys have been studied in great anymore then steals so even for that we cannot
get properties qualities as good as but pollution standard panhandler proof welding process so police shows insufficient food availability and high cost the tone an issue with structure and properties the
scarce they need to be studied in great detail before we can actually commercially USA fiction sterility time
history find temperature
history and stresses unimportant for what
problems so the issue is how do we get the time tempered history and how we we get this stresses for different welding conditions for frictions stumbling of state 1 of the ways in which these types of problems have been addressed in Putian welding is by numerical simulation
off heat mask and momentum transfer during welding in the crucial zone and in the heat of prison so here we we
take the same approach
we solve questions of conservation of mass moment and and in the way
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velocities and analog pushed him because is very difficult to measure velocity so
what do we do we take limiting cases in which we have analytical solutions that means that if you take it or taking
place and employing a little pain and you say OK I know from experience what the booming looks like so I'm going to do and analytical calculation
of what the velocity field will look like if I assume that this is simply a discussed flock in which the floor is generated by the movement on the shoulder of the top and then we have
got analytical solutions that you can do in the back of the enveloped effect and the love estimated demand and then at you can compare this analytical solution which what the calculated numerically by solving warden the immigration that in 10 minutes and the advantages you can actually do these calculations very
easily the calculation scheme can be put on a spreadsheet and the spreadsheet is available in Cambridge University Web site and also and
the website that instead my my employer and that
there also described in detail in this paper in activity an applicant from velocity and temperature we
can actually measured the force on the tool as the tone will set out these
Taylor sports can be computed and then we can see how would those combinations by visiting the government been committed Standard dynamometer over to strain gage or the other possible
techniques and there seems to be a predicting will be paddles and the chain's reasonably well 4
different thickness of material so temperature
velocity fields there was the last 1 we want to compare is blocked on the too
this is important for it reasoning that will become clear in a moment but for now we have looked at um variation of Park with wielding speed and with rotational speed of the tool and we seem to be
getting trading would match with independent experimental results so
the Butterfield's velocity field forces and now we talk so the point is if we believe that the model then there is a better probably that the pummeled cycles will you use for Michael structure prediction and 4 prediction of maps of good durability is likely to be a little more accurate than if we can on palliative care model so we have gone but as
far as we could go with variable results from Kelly beating our model and
then will be be using these but before going to the actual field I want to for you 1 last Bill graphs on on what date model results can be useful and because not everything can be measured 1 of the things that cannot be measured reason is this sticking part sticking card gives us the great public tool on the plasticized material and that dictates how would the flow pattern is going to be and we sure here that there is at an
optimum short diameter for each operating conditions when the tools green on the plasticized material is maximum and it has been shown that if you on the left or right if you do not lose an optimized to inform the diameter the there is a good chance you needed a defect in the well so
structurally sound and reliable wills can be obtained using computer models 5 minutes I know you know what 1 of I
didn't know that it was so boldly lecture was have much here we have Thomas cycles for the condition
and that we're are not going to be looking at the Michael structure might steal and the dynamic there so here and we are looking at temperature cycles on the top player in the middle playing and the bottom claims and the point here is the coordinates do not had it all that much but the
temperature and the bottom planes can be aboard 118 degrees lower than the temperature the top things
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the experience and the fusion welding if you go much faster equal must faster than is expected but here much faster means only about 20 parties prosecutors in the 100 to 500 New England
not looking at is a willing when can cool very very rapidly it's not bad and it can be as low as probably 5 degrees centigrade process that's the typical and was looking at In
contrast if you had at the end of the 2 they temperature fearless and do what's in the great debate change but not it's not something to write home about so and
if you wanted a different structure you actually have to credit winning speed that's the most potent but most potent pitiable and is validated by other peoples independent work with
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Michael section we we did this and what we found was the most important thing is nothing worked nothing worked on TV the people came um stored energy about minus 200 euros but I about 3 . 7 jewels paragraph for Frosty and then of course we were able to predict the
effect of cooling lake and we expect it to be agreement before and I believe in standing heightened by light and areas in Michael structure that shows exactly that and this
is reported in the literature and welding done well and we're able to predict qualitatively this is like a
structure quantitatively we have done some calculations but it
means to experimentally delegated by detailed quantitatively telegraphing that that work will be done later on in the apart from the Michael structure the other
thing that is very very important is here our colleague warning about the life and the value that is important here is that high cost and the durability of the tools and the tools so
actually undergo a lot of stress and a high temperature so if we look can Argentaria means they actually
need is if we're stuck with it too and we must do fictions .period will be Our goal is to provided guidance for the tool to to
last as long as it can and for that we are developing maps in which
we consider the normal stress the shear stressed New demanding and
also new proportions and we calculated the result and maximum CIA stress on the 2 and we
compare these when she has strained public too so we
take a show understandably too and what it endures in terms of this year's test without injustice in this issue is larger then make cooling will last longer if we
tried to win Foster and the and the new heat input the need to lend his lower the temperature is mistresses are higher so if we'd had parameters this Texas change and the temperature changes and
therefore that Poland deliberately changes so if we're stuck with a problem we must wear those maps will provide them with guidance as a frustrated to for the tool
to last as long as it can allow me to so just 1 up another stuff and here we show it
plot of shorter than diameter passes to rotational speed and these solid lines on the and on the stand of the Bloomberg divided by the stressed that experiences so a
fact obtained his good In fact about 1 or 2 we'll make anybody not worse because you don't know what we happen so here if we go we didn't lost speed the safety is higher if you go try to go very fast there is a chance that the tooling on be that happy and here again if you try to win the teacup play then the problem would be a little more difficult then if you will with a place I will stop
here thank you thank
you all thank you in particular for giving a talk on numerical analysis that was not boring and you find that I have did I have any questions that a nice but I have a question mechanism offered this fiction stability people feared group
date of the from the decision-making at Question Time a
diffusion and of the ballast to diffuse so in your review view of the each mechanism is most of important for standards In other than most important diffusion is commonly fusion because without heat there is no will even solid-state Willie
what is the debt whose speed has a very strong influence on the teacher development so
from their given to my mind that if the was previously important then that there must be some influence of ability to choose inductees normally immediately any type of ballistics accepted no I'm serious on it on a more serious this thing it's a much more on the process that anything like this and the type of wielding we do we did and what called directly it's explosive welding the mechanism here is gradual and that's the reason I was not trying to make fun of you costing billions trenches it's a it's a it's a pretty reasonable costs and writing and I I don't continue audiences I'm
just a fact that question because I don't know much about this topic
what is said to have actually made off and is there any possibility for improvement of performance by changing images of the 2 hours and some constraint the you have to following With the 2 material and the tools materials currently used polycrystalline we were in Niger and also sometimes strong stance and just last week the science and technology of reading and learning actually announced prize for the development of 2 it went through the 2nd University's Professor Prodi and his team and being developed at tool and made up of the media malaise but not the medium is more
expensive than gold and and and that is
what makes me somewhat nervous so far there have been reviewed by heading and literally others on materials and tools 2 they're available in science and technology of wheeling and dealing the question was also of the
materials those of other the sign of the shape of the tools you can comment on that and also on heat transfer through the back of the well because Europe pushing stronger so I guess said being
captured by the transfer to of sorry I I was with the legendary quickly I was passing through the top of the heap transplanted the backplane distinctively important because it determines the temperature between really pretty significant you she change the heat transfer coefficient of important players and will change everything will change that would few inches the stresses and therefore will also attend the to the women team yet so that the sign of the process it's not only in the tool but also includes the body of material assumes the environment it also is terribly important to get the right putin shorter if you you can global 5 from the optimum yield vaporized in terms of having holes in the In the weather people have actually declined the complete paper on the itself thank you so
I give what you think is the ideas that were purchased use the to achievable and the
damages more more determined was a problem into a different approach to entertain Estonia likes that it is consumer will to the extent that school materials get embedded in the will and the can a and can develop them with the appropriate edition so that they will let alone would be a composite many middle and deliberately created and structured that would be an exciting idea but for now willing communicated very conservative and we have more novelist and and less hopeful about that particular issue would like to end in common :colon In the
materials the wrong set of materials to put inside steel but in principle a
consumable do using a steel would be IT forum sports will
spot with me if you can have a tool of compilation very close to the completion of the final product is only available and the automotive industry would be very very excited about you work 1 your ideas sorry I misspoke want add that is actually a pattern which is for consumable frictions traveling to Seoul is 1
of the problems that fiction sterility as you all know you stumble on areas that it's real 1 of them the right to so thank you should asylum ,comma I have another question on that institutions
so you have to stop the use of the Finnish it's very this is something you work on how to make the decision
faster shorter consumers about the brother but it is more useful for for the transient processes like the spot will here we have focused mostly on steady-state processes so this particular talk was not focused on that and we have not worked on that important problems the daily the
problem was too is that the cost of the very high temperatures that know you've seen before Is it said would that happen at any temperature because there were some Japanese experiments done some 5 6 years ago when the weather gets back 7 800 degrees centigrade With that had a 2
to prolong the life of the tomb the problem with this tool is both temperature and severe stresses he made in a condition of the the actual mechanism for neighboring nations ranges from chemical degradation In reaches there is the action and the disintegration of the surface of the 2 getting embedded in the good materials to the notion of the sufferers and in extreme cases the break-up so here we have a whole range of problems with the depending on the specific material and when information I am sorry this is a general answer about the yeah McCollum questions from the enlisted the question Milovan but it is a question from rustic but the that you see in any difference in them off lies between problems than regular and the PCB entities Polly cubicle nite flight to material we have not compared it except for review in which we have looked at the General but general suitability and the advantages and disadvantages of of the use of those tools materials that available in details in science Science and Technology of winning and joining in interview that says view on the if you are right
that certain always kind of questions thank you very much


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