Oil quenching Stainless lets hear some stories

Rob, I have enough of Gib's steel left to do it that way also. I intend to do both. The first run by ramping the steel and the second run by putting in the stabilized oven and quenching when the steel reaches austinetizing temp.. It is very time consuming but since this is stainless it may show us some pretty interesting things.

I am doing the triple quench piece of the first run now. I hope to also do the single quench piece of the second run this evening.

The second run will be just as the first except the test pieces will be put in the oven after the oven stabilizes at the austenitizing temp. and it will be quenched when it becomes critical.

How's that??

RL
 
Okay. It is 10 to 1:00AM EST and I just pulled the three quench test piece of test run #1 from final temper. To keep things as consistant as I can I will let it rest, as I did the single quench piece, 12 hours before grinding decarb and testing.

I also pulled the single quench test piece of test run #2 from temper number two. It should be out of final temper by 3:30AM EST. Again, to keep things as consistant as I can I shall allow it too to rest 12 hours before grinding decarb and testing.

Tomorrow afternoon I will detail all HT details including oven temps, oil temps, times, etc., etc.

Now I am going to HT a store bought pizza and watch some Fox News.

RL
 
Roger,
YOUDAMAN!:cool: This is a thread I'm really interested in.
Getting Rc tests done on oil quenched 440-c is something I've wished for since early last year when I first heard about using oil to HT the stuff. Your results so far are quite encouraging.

Thank you very much for stepping up and taking the reins on this.

Enjoy that HT'd pizza! :D


All the best,
Mike U.
 
Mike, dun eet the pizza. Didn't even burn it this time.

Yeah, we'll get two kinds of single vs. triple oil quench 440C on this trip. Takes alot of time though. I have about 12 hours in todays triple quench counting the three 2 hour tempers. You gotta baby sit it too the whole time. Just writing this is a break for me now.

Tomorrow I got to triple quench for the guys over at the 5160 thread but I'll have Rockwell results for today's (or is it yesterday's) triple and single 440C quenches; and specs on how they were HT'ed.

RL
 
Okay. The triple oil quench of test piece #2/test run #1 are in:
-------------------
(rounded to the nearest 1/2 point)

58 HRc
58
58
59
58
58
58
58

It is 58 HRc
I don't know how that 59 got in there. Could have been the operator.
--------------------

This piece was heat treated as follows:

Test piece placed in cool oven (no atmosphere control)
Ramp to 1865 and soak 5 min.
quench in warm oil to oil temp.
Return to hot oven and ramp back to 1865, soak 5 min.
quench as above and repeat as above for a total of three quenches
temper oil temp. steel immediately at 375 F. for 2 hours
still air cool and repeat temper for a total of three temper sessions
Rest test piece in still air 12 hours 45 minutes, grind decarb. and Rockwell test

Here are the temperatures when the test piece was put in oven and oil:

1st auteniziting - oven: 65 F. / oil: 131 F.
2nd auteniziting - oven: 1343 F. / oil: 134 F.
3rd auteniziting - oven: 1350 F. / oil: 132 F.

Two things seem outstanding to me. The hardness did not remarkably change but the triple quench piece exhibits a flat test pattern. Compared to the triple quenched piece the single quench test results are not flat.

Decarboration was deep enough but workable and I would make a blade of it if I started with no less than 5/32 stock.

Roger
 
Gib, although I did not check that during these runs I did do some timing tests a few weeks ago and am lucky enough to have kept the results.

From a cold start, with a small block of cold steel in the oven, it took 63 minutes to reach 1860 F.. It just happens that 1860 was one of my target temps. when I did that.

When the oven is already hot it recovers alot faster than if it were cold. I can only guess at how long it took to get back to 1865 after falling to 1350 F.. I have to say greater than 5 min. but not much more and I just don't know.

The Even Heat drops like a rock when you open the door when at those higher temps..

I can take some time samples when I do the triple quench for test run
#2.

Gib, If I only open the door to take a peek at steel color it will fall approx. 90 degrees from 1865 F.. I know this because that is what I had to do during the HT of the #2 run single quench test piece.

I will have those test results after 3:20PM EST today.

Gib, I am NOT going to be putting the triple quench piece for test run #2 back in the oven at 1350 F.. I am going to keep the steel in the oil until the oven recovers to 1865 F.. Putting the steel back in the oven I am hoping to only lose a little over a hundred degrees.

Roger
 
Okay. Stop your grin'n and drop your linen. The test results for single quench test run #2 are in:
--------------------
(results are rounded to nearest 1/2 point)

55.5 HRc
55
56
56
56
56
55.5
56

It is 55.5 HRc
---------------------

The single quench test piece was heat treated as follows:

Stabilize oven at 1865 F. with a test block of 300 series steel in oven as a reference.

Place test piece in oven - oven was 1774 F. upon closing door

Quench test piece immediately in 132 F. oil when color is consistant and that of the reference (greater than 1 minute but probably no more than 2 minutes after oven recovered to 1865 F.)

Temper oil temperature test piece immediately at 375 F. for 2 hours.

Still air cool, repeat temper for a total of three tempers

Rest test piece in still air for 12 hours, grind decarb and Rockwell test

Roger
 
Gib, I am doing the triple oil quench 5160 for the guys over on pig's thread this evening. I am austenitizing the 5160 at 1475 F.. I timed how long it took the oven to recover to 1475 after putting the test piece in. When I got the door closed it dropped to 1399 F.. It took 1 minute 13 seconds for it to recover to 1475 F..

That might be of some use to you. I hope to do the next triple oil quench on this thread's steel tomorrow. I will time that recovery too.

ADDENDUM: I must have made a mistake. I just timed it on my third quench of the 5160. It took 2 min. 12 sec. to recover from 1385 to 1475 F..

RL
 
4:20PM EST - The oil is heating and the oven is ramping. I should have results on the triple quench early morning EST. RL
 
I'll try to get the details of the HT procedure here this evening. I have to go out on the road for a while and don't have the time now.

But...

the triple quench 440C is 52 HRC

RL
 
Sorry to be late posting the procedure. I've been in different directions of late.

Here is how I did the last triple quench 44C:
-------------------

Ramp oven to 1865 F. and let stabilize

Put test piece in oven

After oven recovered to 1865 F. check color of test piece to match that of a 300 series stainless reference piece in oven (probably in the area of 1 minute or a little more after oven recovered)

Quench immediately in pre-heated oil to oil temperature

Allow oven to recover and stabilize at 1865 F.

Repeat all above for a total of three quenches

Temper immediately at 375 F. for two hours

Still air cool to room temperature and repeat tempering for a total of three 2 hour tempers

Let still air cool 12 hours, grind decarboration and rockwell test
---------------------

Oven temperatures after getting the test piece in and the door closed:

First austenitization: 1790 F., Time to recover to 1865 F.: 1 min. 50 sec.

Second austenitization: 1819 F., Time to recover to 1865 F.: 1 min. 35 sec.

Third austenitization: 1819 F., Time to recover to 1865 F.: 1 min. 24 sec.
----------------------

Oil temperature at quench

Quench 1: 129 F.
Quench 2: 129 F.
Quench 3: 129 F.
-----------------------

Here are the Rockwell test results:

(test results rounded to the nearest 1/2 point)

52 HRc
52
52
52
53
53
52
52

It is 52 HRc
------------------------

RL
 
Thank you very much :)
This has been very insightful. My current heat treat set up takes a while to get the blade up to an even color, which I beleive was making up for my not keeping it at color for very long. I'm probably getting a sort of differential temper since the edgen gets up to color much faster than the rest.
Because of your test, I'm going to go ahead and hold at color for 3-5 minutes on each quench and see how things go, especially now that I'm building a forge which will get things up to temp much much faster. The biggest question will be de-carb now, and I'm not too concerned about it since I usually do a fair amount of grinding after heat treat.
I'm still pretty confident that all of my triple quench blades so far are hard enough, but I'm glad I found out that a 5 minute soak does better.
 
Exactly Matt. The 440C with its admirable amount of chromium requires time for those carbides to go into solution. I believe you are wise to soak as long, within reason, as your forging will satisfactorily permit. Remember the 5 minute soaks of my first test run tested 58 for both the single and triple quench test pieces.

Now, what might really help is I send these unalthered and intact pieces of both test runs off to one of you guys that know how to visually check grain size. We have a record here on this thread of the HT procedures used and I stamped all four test pieces before heat treating so they can be kept track of.

Matt, the decarb on my triple 5 minute soak was deep enough but not enough to make a 5/32 beveled hunter size blade to thin after grind. That was my observation to myself. A couple test pieces of 440C by you experimenting with will better answer you decarb concerns. Remember the steel is only decarborized to the depth of pitting and the remainder is okay as far as carbon content is concerned.

RL
 
Yeah, so far I don't really get pitting so much as an overall black scale. Its not hard to clean up at all, and isn't deep.120 grit wheel on my slow speed grinder usually takes it off in a pass or two.
 
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