austenite transformation during tempering in martensitic steels and a few other questions

If a martensitic steel like W1 is quenched to 350F and then held there to temper, the 50% retained austenite transforms to bainite, see Krauss.
However what happens to the austenite if it is tempered hot, ~ 950F. I have read it won't transform the austenite but conditions it so during the cooling martensite forms. The basic reason is that during the temper the MS point of the steel is raised. What I don't understand is why it doesn't transform to pearlite and instead is "conditioned".
Regarding toughness testing, if you examine torsional graphs they show a huge peak at low temperatures, usually ~325 F and then a sudden fall off after that usually attributed to cementite precipitation. However the charpy and izod tests don't show this at all. I was wondering if this isn't just an issue of grain alignment of the test piece because if the grain was aligned with the break as opposed to against it it would make a huge difference if the grain boundries were reduced in toughness due to cementite formation.
Is this the case. Does anyone know of charpy tests over a wide tempering range which include the grain orientation both opposing the with the break and do they have the same peaked nature of the torsional graph. Crucible has the tests for some steels, but only at select points they don't have the full range of values over a wide tempering range, 300-1000F.
In regards to compression strength, Crucible notes that CPM versions of the same steels are 10-15% stronger under compression at the exact same HRC hardness. Now a HRC value is a test of compression to the point that plastic deformation is seen over an extent far larger than the grain size of the steel so I would think it would hold to compression in general. What is the theory behind the difference in behavior between compression say a mm sized hole (HRC) to a cm point, hitting a knife edge into a nail and having it deform (this is one of the promoted advantages).
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Cliff Stamp
snipped-for-privacy@physics.mun.ca http://www.physics.mun.ca:80/~sstamp /
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Cliff Stamp wrote:

1. Look for the isothermal TTT diagram of the steel. There are temperatures, where transformation is extremly slow.
2. Please use SI units! This is not a US-only group.
Michael Dahms
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Yeah. :) Good answer. :)

MD, CS is a metric-assed Canuck, not a 'murkin, BTW. :)
Alvin in AZ (Gadsden Purchase, born and raised and worked)
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On Wed, 4 Jan 2006, Michael Dahms wrote:

Yes, this explains why Bainite doesn't form in D2 when tempering low but not why pearlite doesn't form when it is tempered high, unless I am not remembering it right, I'll check. So if this is the case then a reaction upon tempering will proceed the same as cooling in regards to austenite to bainite or pearlite?
I found a bit of it anyway, when the martensite is tempered high it changes forms to tempered martensite and this changes the strain that the ausenite is under which effects the TTT curve for it, specifically it raises the Ms point which allows the cool after the temper to form more martensite, maybe it shifts the curve further to the right for the same reason which prevents pearlite formation.
I also found some course notes which say that pearlite does indeed form on high tempers so it is obviously steel specific.
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Cliff Stamp
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Cliff Stamp wrote:

Right. For me, understanding of isothermal transformation is much easier than understanding of an continuous-cooling transformation.
Michael Dahms
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Humph - the percents are SI :-)
(Amazon.com product link shortened)36434189/sr-1/ref=sr_11_1/104-4951117-3159123?n(3155
If that corks screws you - try the ISBN number in the book section - 0780310500 Well done book by Wildi - IEEE Press - Metric Units and Conversion Charts - nice handbook. (for all sides of the pond - and I don't know Theodore but am an IEEE member and Life member of the IEEE Electron Device society (tubes to ...).
SI is nice, however many documents are not SI they are Metric or other. Yes many others.
SI stole the long traditional names of quantities. I still think the French based Society did that on purpose. Some it was so obvious.
Martin
Martin Eastburn @ home at Lions' Lair with our computer lionslair at consolidated dot net NRA LOH & Endowment Member NRA Second Amendment Task Force Charter Founder
Michael Dahms wrote:

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Martin H. Eastburn wrote:

You can't steal something that is already yours. The BIPM has had responsibility for world metrology by international agreement since the Convention du Mtre 1875. See: http://www.bipm.fr/utils/en/pdf/metre_convention.pdf
Saying that the BIPM is "French based" is like saying the UN is "America based". Factually correct, but not particularly useful to understanding the decision making process.
Incidentally, Google converter is handy. Try a search for: 350 f
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snipped-for-privacy@iname.com wrote:

Half my metallurgy books have conversion tables in them, and all those, I've marked the very edge of the pages with a felt-tip marker. Easy as pie to find conversions that way. ;)
But what about this thread's original questions?
Alvin in AZ
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snipped-for-privacy@XX.com wrote:

Hence, posting-*authors* should bei able do the conversion easily.
Michael Dahms
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Actually saying that in 1875 it was a world power isn't it - just a localized one.
The Metric system didn't unify in Europe until ?? Si ?? - metric screws in Germany and France and.....even Japan didn't match until the last 10 years!
There are three French based units. CGPM, CIPM and BIPM. 18 members of various International Organizations and National Laboratories make up the CIPM and head their team. This is the only International unit. It does have a French charter.
BIPM - has an 'international staff' of about 60. That doesn't mean much.
The issue was when a unit of measure was called one and used by science then the British or English or German name is replaced by another - with no changes in value. There was an asserted direction towards French names and names other than the developers. e.g. the old dead men don't care - we do.
It was felt during the time - not many years ago - that it was a get even time. I think Europe was mentally reeling from the earlier purges of the smart people and the people that questioned. I also think they missed the boat in the restrictive education system they have - main-lining peoples lives at young school kid ages. Many a smart person bloomed later in life or in synergy with another.
Martin
Martin Eastburn @ home at Lions' Lair with our computer lionslair at consolidated dot net NRA LOH & Endowment Member NRA Second Amendment Task Force Charter Founder
snipped-for-privacy@iname.com wrote:

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