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View Full Version : Input needed - How to present heat treat info in the knife steel app



Gator
03-24-2013, 03:07 PM
Hi All,

I suppose main audience for this question would be makers and heat treaters, although anyone else interested in heat treating data or having any feedback is more than welcome to comment.

Long story short, asm international contacted me regarding my app, and offered some help with info, of course I am quite proud that the largest scientific group in materials science took interest :) Anyhow, based on all that I am considering adding HT info to the app, or another version of it.
Unfortunately, I have never done or studied HT, just researched few things on the net here and there, which isn't nearly enough. I don't plan to do HT myself, but what I do want to know what is acceptable/useful information on heat treating given alloy.

I've seen different formats, starting from few numbers like this on Crucible HT page (http://www.crucible.com/eselector/general/generalpart2.html) and ending with pdf files having 2-3 pages of more detailed information including charts and diagrams.

Obviously, I can not include few thousand pfd files in my app, even if i had all of them. On the other hand, it is unlikely that someone will need all of them anyway. My goal is to provide useful set of information which is enough for a maker or heat treater...

For example, if I have the following info on 1040 steel, is it enough for you to work with or diagrams are necessary?



AISI 1040 steel (composition and cross reference data as in the current app)

Forging. Heat to 1235 C (2275 OF). Do not forge below 870 C ( 1600 OF)

Recommended Heat Treating Practice:
Normalizing. Heat to 900 C ( I650 OF). Cool in air

Annealing. Heat to 835 C ( IS55 JF). Furnace cool to 650 C ( I X0 F).
at a rate not to exceed 78 C (SO F) per h

Hardening. Heat to 845 C ( IS55 F). Flame hardening carbonitriding.
and liquid carburizinp are suitable surface hardening processes. Quench in
water or brine. Rounds less than 6.35 mm (I/-l in.) diam may he oil
quenched for full hardness

Tempering After Hardening. As-quenched hardness of approximately 52 HRC. Hardness can be reduced by tempering

Tempering After Normalizing. For large sections. normalize by
comentional practice. This results in a structure of line pearlite. A tempering
treatment up IO about 510 C ( IO00 F) is then applied. Mechanical
properties not equal to those achieved by quenching and tempering. Resulting
strength is far higher than that of annealed structure. Normalizing and
tempering often applied to heavy forgings

Recommended Processing Sequence

Forgings
Forge
l Normalize
l Anneal tif necessa@ or temper (optional)
l Rough machine
l Austenitize
l Quench
l Temper
l Finish machine



If there is another more useful or shorter format I'd like to know :)

HHH Knives
03-24-2013, 03:24 PM
Im happy to hear you may be adding some HT info to the site. The stuff you presented on 1040 would be a very adequate format.

Thanks gator.

ajhuff
03-24-2013, 05:25 PM
TTT diagrams.



-AJ

Dave Martell
03-24-2013, 06:53 PM
I have nothing that I can add here but I love that you're headed down this path Gator. Cheers! :hoot:

Gator
03-24-2013, 07:39 PM
Well, I am glad to hear I got something right ;)

@ajhuff - I am not sure I understand what does it mean TTT diagrams?

franzb69
03-25-2013, 06:52 AM
awesome info! =D

Don Nguyen
03-25-2013, 10:28 AM
Gator, this is awesome!

A TTT diagram is a Time-Temperature-Transformation diagram.

It plots the temperature versus the log of time, and the curves will show you the tranformations that result from different cooling rates.

Here is an example for 1095.

http://i44.photobucket.com/albums/f24/hephaestus61/Heat%20Treating/1095-ttt-point-89.jpg

To get martensite, the cooling rate has to be quick enough to avoid that curve, so at the quickest, 0.8 seconds or so around 1050 F. Different microstructures/combinations of microstructures will result with touching into the curve.

Gator
03-25-2013, 07:21 PM
So, is TTT required? I'd rather avoid images and pdfs on the phone, and local storage limitations. On the other hand, if it's something vital, I have to come up with some way of doing it.

ajhuff
03-25-2013, 07:46 PM
I don't know about required but TTT curves are the essence of heat treating. Extremely useful though that's for sure.

-AJ

Gator
03-26-2013, 11:48 AM
Well, you're the user of the app, or intended user :) So you tell me what is required, to me it's all data in different formats...

franzb69
03-26-2013, 12:09 PM
i'd love to see which steel is ideal for water, oil and whatever quenching....

Gator
03-27-2013, 12:25 PM
Some of that info can be inferred form the AISI names, W for water, A for air, O for oil... More precise info needs the data I am trying to figure out in this thread...