kb0fhp

Jerry - you might want to look at 300M - it is available at the high hardness - can be practically air hardened, and it is really tough for this hardness. It was used for landing gear and still is for large commercial aircraft. It was used for navy aircraft - and you know that takes a beating. Heat treating is pretty conventional - and you can get it very hard - HRC 60+, and it naturally has a fine grain size.

Scott

There is also the issue of being in the public domain. One criteria is that it is an improvement on the prior art that has not been published elsewhere. Cryo and all the other similar processes, have been in the literature, for many years prior to the application of patent.

Remember - deep pockets are the key. Why pay a lawyer $500/hour for something than can only generate a small amount. Not cost effective. Generally it is the threat, and the on-going cost avoidance that people pay....

I would suspect, if a lawsuit occurs, then Admiral would be a party - after all, they have the deep pockets, or at least deeper pockets.

Induction is fun to play with....As long there is proper schielding of the power supply unit you are fine. THe units come schielded....you might tick off a local ham radio operator, but they are safe. They are commonly used all over the world for hardening all sorts of stuff, like cam shafts, etc. It works better with symmetrical things....because of the concentration of the field.

Scott

Are the relays working properly? Did you have a broken thermocouple on your excess temperature instrument causing the instrument to trip? Could you have a crack in one of the elements that opens up when heated? Sounds like a system reset somehow - or a relay that is causing problems...Could you have an open at the element?

Do you have a circuit diagram that I could look at to help you troubleshoot?

Scott

Also take a short day trip to Brighton - quick train ride down, and see the antique shops and such...not as good as in the summer - but it is a lot of fun.

THe museum of Science and Industry is also fun, along with a trip to Greenwich - lots of fun standing on top of two different time zones, and seeing the lazer that makes GMT. They also have a cool time piece museuem...it is also a nice trip down the Thames. See The globe theater... all kinds of stuff to do - Pickadilly at night, the theather district, and absolutely visit a few pubs - good cheap food - and the beer is excellent.

ABSOLUTELY CORRECT - the crack was pre-existing, and probably a quench crack, or a crack that formed at temperature. THe shiny part is the newly fractured surface, ad the dark areas are the region of the preexisting crack.....

I have trouble falling asleep. Not trouble sleeping - once I am asleep - I am gone. But I have found that using a small bit of benedryl - the childrens chewable is a great help. Take it immediately before bed, and usually am asleep within 30 minutes. Without it - I am awake for hours. My wife on the other hand falls asleep as soon as she is horizontal - usually within 5 minutes - and I mean fast asleep and snoring. I envy her. I guess she has a clear conscience....

I saw the show too - it was right after "Modern Marvelss" about aluminum. I was having trouble sleeping and the aluminum show came on at midnight...it was after 2am when I finally when to bed. I enjoyed it. Yes, there was a bit of oversimplification of the details (on both shows), but nonetheless I learned quite a bit about steel making. It was interesting the focus on Lehigh University for the steel, and Worcester Polytech on aluminum.

Over looking the details - it was a good show - if the talked about the details, it would have lost 90% of the audience......and lost the visual impact....

We gotta maintain our "voodoo magic" aura.....

I think you could say that the lower the Ms the more benefit you will see, since the Mf = Ms=387. But overall I think that would be a valid statement....

Look in Timken's Practical guide for metallurgists - it is a free pdf on their site - I have also attached in someplace on here.

But here is the equation:

Ms (°F) ~ 930 - 600 x C - 60 x Mn - 20 x Si - 50 x Cr - 30 x Ni - 20 x Mo - 20 x W

Mf (°F) ~ Ms - 387

Here is an interesting site - http://www.thomas-sourmail.org/martensite.html

THere are others on the web - but I would trust those cited above.

Scott

Actually that is commonly used. Also the use of austenite and a crack blunter - look at AF1410 (14% Ni, 10% Co 0.25% C)... in that they use transformation of austenite around carbides to provide improved fracture toughness.....

the intragranular ferrite plates that they speak of - as best as I can tell, are small islands of ferrite with in the grain - new grains have nucleated of ferrite. Based on the paper, it increases toughness - think of ferrite as soft marshmallows in the matrix. The ferrite absorbs the shock - effectively requiring more energy to fracture....

At least that was the way I understood it.

Scott

OK - when looking at a common steel that you might encounter/use - I chose 6150, and used the same parameters for each - same chemistry, austenitizing temperature, time scales, etc. Within the limitations of the calculations, it doesn't look too bad. Remember in the calculated file to subtract 273K to get the C temperatures. The basic phase fields tend to correspond with temperature and time - actually pretty well. THere seems to be a disconnect with the TTT diagram and the Bainite start temperatures. But overall - I find that it is pretty close on the whole - good enough that I would use the calculated data with a bit of understanding and caution. Certainly, I would compare several more to verify - but on this first comparison - it is pretty good. The CCT diagram appears to match pretty well....One thing that you have to pay attention to is the maximum cooling rate - note the differences when I changed the maximum cooling rate from 100K/s to 35 K/s

Actually - it doesn't look too bad. When you input "0" into the temperature - it defines the austenitizing temperature as Ae3...let me try and find a simple one and I can compare data.

http://calculations.ewi.org/VJP/TTTCCTPlots.HTML

Site allows you to input a chemistry of common elements - and poof - out comes a TTT or CCT diagram

I will try and find a way to post it

I just wanted to let everyone know - that I gave my paper on the history of quenching at the recent Heat Treating Society Conference in Detroit. It was extremely well received - with close to 150 people coming to hear it. I got lots of questions and very nice comments from some Japanese metallurgists who attended. I want to thank each one of you for your patience and for answering my dumb questions.

Again, thank you very much.

Scott

OK - since it seems rounded at the ends - it is cooling off too fast. You need to get the melt much hottor. It apparently has inadequate fluidity to reach the rends of the casting. With enough super heat - it will work well. You are doing well - much better than before!. I like the statue!

Scott

I smell dinner! I like venison medallions with mushrooms in a brown gravy....served with young potatoes or rice.

I think you will get your limit this year - but the deer will only show up again when deer searson is over - they do that just to tease you.

Scott

OK - an element is an element - but remember elements have an electron shell filled with varing numbers of electrons based on their position on the periodic table. They also have a nucleus which is filled with neutrons and protons (from http://www.aboutnuclear.org/view.cgi?fC=Th...e_of_the_Atom):

Even though the number of protons in the nucleus is the same for all atoms of a particular element, the number of neutrons in the nucleus can differ for different atoms of the same element. Atoms of an element that contain the same number of protons, but different numbers of neutrons, are called isotopes of the element. Isotopes are identified by adding the number of protons and neutrons together -- a number which is referred to as the mass number.

For example, hydrogen: the element hydrogen has 3 isotopes: hydrogen 1 (also called hydrogen), hydrogen 2 (also called deuterium) and hydrogen 3 (also called tritium).

Hope this helps.

Scott

There is never any question that cryogenic treatment works for recovery of retained austenite - as such I recommend it. But I have problems with the antedotal stories of improving copper wire - making golf balls that fly further, etc.

I did a lot of studying on this when I was in the "Strength of Materials" phase of my Mechanical engineering degree, I posted a write up on it in my blog Scary sharp!: Cold Hardening

It comes complete with a link to the original paper and some nice little diagrams! Easily the most easy explanation with real world examples that I have ever found on this subject!

Based on the table of materials that showed a considerable improvement, and comparing it to those that didn't show an improvement - one thing is clear. The materials with strong austenite stabilizers tended to show greater benefit. Those that didn't have any strong austenite formers or stabilizers did not show any improvement. If I get time, it would be interesting to correlate the Mf temperature to the improvement and the treatment temperature. I suspect that the lower the Mf temperature, the greater the improvement via treatment at very low temperatures.

Further, most of the articles sited were mostly the free type trade journals - with articles written but not peer reviewed. Only 2-3 of the Journals were really peer reviewed - These were Jounal of Heat Treatment (the old Wolfson institute - now operated by IFHTSE), and J. Mat. Sci.....

Also this article above was written as a marketing piece - although a good one - to sell Linde nitrogen or to buy their equipment.

Slow heat to drive off the moisture - I think you got it hot too quickly if I understand what happened....

Did it crack?

Scott

Based on my dealings with the oil and gas business - they are probably 4340 with carbide inserts. The extensions are probably 4340 also. But the could be a tool steel - you might want to get an idea of the carbon content by doing a spark test.

Scott