Steel won't harden need help.

Mark Behnke

Mark Behnke

Well-Known Member
!084 FG

Using anti scale then into the oven preheated to 1500*
The temp drops to about 1300* when the oven is opened for loading then up to 1500* hold 5 min. then into Parks 50 @ 80*straight up and down agitation for aprox. 30 sec. air cool and test.

Rc 45 -50 depending on where I test

Did a second cycle same as above w/10 min. soak
same results

Read Kevin Cashens recipe and did a small coupon same as above w/ water quench (50*)same hardness as above.

Whats wrong here?

Picture of blade and coupon 1/4" X1-1/2" x 3/4" blade has anti scale on it because I was going to quench in water but holding off after the cupon results.
1084 dagger HT 001.jpg1084 dagger HT 002.jpg
 
my guess is it's not getting hot enough/long enough to go into solution.
set your oven for 1550, soak for 10 minutes and try it.
 
Where are you measuring the hardness on the blade? If it was the ricasso and it was still about 1/4" thick after grinding you may just be seeing being too thick at that point to cool quickly enough to form martensite or at least avoiding a slack quench. Same with the ticket. Even though Aldo's 1084 has some chromium in it it's still on the shallow hardening side of things. I don't know if your hardness tester can be used out towards the edge of the blade, but if you can, give that a try. Maybe just try to cut through some wire with it and see how the edge holds up. Just remember with shallow hardening steels that there is a maximum that they will harden to especially with a fine grain. Then it will do it's differential hardening thing.

Try what Tracy told you. If that doesn't work the above may be your problem.

Doug
 
I agree, could be either one of the above mentioned things.
If a coupon does not go over 50RC even in water quench something is definitely wrong. Problem could be in the RC testing or its a temperature Problem.
Where did you place it in the oven? Flat on the bottom? On a Rack? Did you at some time check the oven for accuracy of the shown temp?
 
Mike, I don't see anything in you recipe that would lead to such a significant fail. Is it possible that there are slight burrs that could be affecting readings? A human hair between the workpiece and anvil can change RHC readings by up to 4 points and a burr easily the amount you are getting. I don't use the pbc antiscale, but I wonder if it is insulating just enough to fail that thickness. Maybe try the coupon without it. Last possibility is a steel mix-up. We all work very hard not to let it happen, but sometimes the gremlins visit.
 
Trouble shooting heat treatments is a matter of process of elimination. Your water test is a good example of this and has pretty much eliminated the quench. I have mentioned before that the quench is most often the first suspicion of many folks but is often the least likely to be the problem. I have a hunch that in this case decarb is not a significant enough issue. I am looking at two things- inadequate soak and proper location for accurate Rockwell reading. I think the water test also skews things away from the Rockwell test location, even on 1/4 “ the HRC should have been significantly different with water even if it wasn’t where we would like it. This leaves the soak, and it is also worth noting that insufficient solution is actually one of the leading culprits when I help troubleshoot heat treatments. Are you forging or doing other thermal operations before hardening or are you using the stock as received? Another remote possibility that I always leave as the final option when all else passes the debugging process is misidentified steel. If different results are obtained with the same steel, this is probably not the case but if all results are the same for the same bar of steel this possibility increases.
 
Thanks for all your quick responses I tested today with just the coupon and Parks 50 trying to keep the variables to a minimum.

Anti scale was used cleaned then sanded w/280 grit on a granite plate before the RC test. The tester reads 1 point lower than the test block. Three hardness test on each heat.

#1- 1500* soak 15min. quench 130* Rc 47, 47, 46.5

#2- 1520* soak 15 min. quench 120* Rc 46, 46, 46.5

#3- 1550* soak 15 min. quench 110* Rc 36, 47, 38.5

I did a HT on a 1080 blade from different source the day before this at 1500* 5 or 10 min. soak quench in same oil and got Rc 64.
I need to check my pyrometer next.

Let me know what you think and suggestions on further testing.

1084 dagger HT 004.jpg1084 dagger HT 005.jpg
 
Last edited:
Have you tested your hardness tester ? there are little flat pieces of steel you can buy that are of a known and tested hardness , they are used to calibrate your tester ! just a thought. B.
 
I have the test plates and it's testing 1 point low consistently.

I used a Harbor freight inferred temp. gun on the interior of the oven on cool down and it read 880 when the oven pyrometer was reading 710 don't know how accurate that would be . I'll switch pyrometers when I have a chance.
 
Your process seems very tight so if you are getting high RC with other steel types then you might try a different source of 1084 just to check off list the possibility that your steel is not what think it is.
 
I just ran into this problem about a week ago with some 1095 I got last summer sometime. I was only getting 45 up to 50 RC . I first checked pyrometer and hooked up additional pyrometers to my Kiln and the temp reading is within 5 degree's of what the kiln reads these readings were from two different meters along with the kilns meter. I had two blades I forged out of 1/4 stock that ended up at 59 RC but the two blades I am talking about are 5/32 stock removal. I repeated my process and bumped the temp and soaked for 17 min and it all came back a bit worse than the first time. My hardness tester is spot on. I have done blades out of 01 after and they came out exactly as planned. I use Parks 50 and I use the whole 5 gallons when I quench. I also want to note I normalized before the first heat treat and repeated it the second time as well.

After all this work I was less than thrilled . I ground of the scale and tested everywhere I could on the blades. My conclusion is I had mislabeled steel. 48 inches worth. I am going to mention it to my supplier in private. Just to give him a heads up . I like him and I know accidents happen.

So maybe this is what happened to you to ??
 
Mark
I haven't tryed to HT anything since last winter when ats34 gave me results I didn't understand, got discouraged and figured I should go to a simple steel.
I have very little experience with heat treating so this is a learning experience trying to intemperate results. If it's mislabeled that's OK I feel the way you do.
Thanks for posting your experience.

Kevin
Did a retest on the 1080 maybe 1084 bladeHRC test 001.jpg
HRC test 002.jpgHRC test 003.jpg
HRC test 004.jpg

A pic of the test block and reading. Two #s on the block 6150 stamped on the edge and the one in the upper left corner is etched 63.1 that's one I've been using and got the reading shown in the picture 62.3. Have another block with 4499 stamped on the edge and 48.2 etched in the corner, got a HRC 47 reading with that block.

After posting this I just noticed that "94" just goes to show how easy it is to make mistakes.

Happy Thanksgiving everyone.
 
Last edited:
You must log in or register to reply here.
Back
Top