I'm so frustrated I could kick a puppy.. Major HT issues... Help needed.

I suppose I am fortunate to have a friend that owns a sophisticated Machine and Milling shop--he is an expert at steel hardening--most of what I do is O-1 or D-2, but I tried some 1084 previously and had a piece from the same vendor, and it wouldn't harden properly--so as another poster suggested that may be the issue--setting that aside, I successfully heat treated some 1084 in my shop before, and the major difference I see between what I did and what you are doing, is I got the steel much hotter to begin with--if I go buy the chart that Mike Riley provided I got mine to something in the 1800+ range. So to start with I would try a coupon with taking it to much hotter initial temp and see what that does for you. For sure whatever you do you need to make sure it is getting hot enough to go non-magnetic--also I will state that I feel all the hoo-ha about how you quench it - have to move it so and so etc. is BS. I quench with the blade going straight as possible into Peanut Oil, and I make a slicing motion ONLY back and forth-like I was slicing through a loaf of bread. Long story short, I would try these few things, and then I would chalk it up to getting a mislabeled or bad piece of steel.

Good Luck--Don
 
UPDATE... Breakthrough!

I left my shop well after midnight yesterday feeling pretty good. I think I've identified my major mistakes.

1. I wasn't letting the Steel get up to kiln temperatures. I made some test medallions from the 1084 and put them into the kiln at about 1300. When the kiln read 1500 I opened it up and to my surprise the steel was still magnetic. I did not give the steel enough time to catch up to the kiln's temp. My solution is to allow the steel to heat up with the kiln from room temperature whenever possible. Because I was doing back to back tests without allowing the kiln to fully cool I compensated by increased soak times and testing with a magnet.

2. For whatever reason the Canola oil is not quenching fast enough for the 1084. I could consistently reach full harness with a water quench, conversely I never got above 40 RC with oil quench on the 1084. However the canola oil did work perfectly with some 5160, reaching full hardness well above 63 RC. I need so study up on how to properly use canola oil for quenching, including preheating, volumes, and agitation.

Materials: I checked my emails and confirmed that I purchases 1084 from Aldo... in 2013. That is all the evidence I have that it is indeed 1084. I had that bar laser cut into some machete blanks. One of which I ruined on the grinder and threw away in disappointment. The other I broke hitting it against a log before any normalization or HT. I made the new knife blade blank from that broken machete blank. And I still have the skeleton of the bar. It is from the skeleton that I cut the test medallions.

Methodology: Discovering the medallions were still magnetic even though the kiln was at 1500 indicates that my assumptions about how long it took the steel to get to temp were waaaaaay off. By the time the kiln read 1650 they had caught up and were non magnetic. I quenched one medallion at 1650, and one at 1800 in the canola oil. These quench yielded the softest results ever, reading less than 20RC for both pieces. I ground half of one of the medallions on the belt sander (both sides) down about .050". I tested the ground end and the non ground end see if there were any changes in hardness deeper in the steel. Harness test on both ends were identically soft.

I then put the medallions back in the kiln and let them heat up with the kiln to 1500. This time they were put in early enough to heat at the same rate as the kiln. I checked them with a magnet and then quenched in water. Both medallions tested at over 63 RC. So the water certainly worked.

I then put in some blade blanks. One small blank in 1084, one medium in 1084 (the one I originally wanted to finish) and an old monster of a chopper in 5160 (that I got from Admiral Steel). I let them all ramp up with the kiln to 1500. I quenched the small blank in water. I quenched the other two in canola.

The small water quenched blank in 1084 was over 63 RC. The oil quenched medium blank was mid 30's RC. The Oil quenched 5160 was about 58 RC.

I read up on the 5160 and realized that I didn't give it any soak time. So I ramped it up again to 1500. Then I let it soak for 20 min. I made sure the Canola oil was at least 135 by heating the side of the ammo can with a torch while I watched the temp with an ir thermometer. I quenched the 5160 in the heated canola oil. It came out at over 64 Rockwell. Success.

So I can get expected and repeatable results with the 5160 and the canola oil. And I can do the same with water and the 1084. And though the results from oil quenching the 1084 is not expected, they are consistent and repeatable.

Some random observations and info: A couple of times I quenched the larger 1084 blade blank and the 5160 blade blank in water. It warped them but still got full hardness. Oddly enough the warp largely disappeared just by heating the blades back up to critical.

And yesterday I found these at Harbor Freight: http://www.harborfreight.com/16-inch-long-reach-pliers-set-38598.html They have been working great as oven tongs so far.
 
So, Question... What is the purpose of preheating the canola oil to 130F? And how critical is this step?
 
It's good you are getting over Rc60, but right out of quench, you could be getting Rc66. Have you tried normalizing and thermal cycling? Try a coupon that way and see if you get Rc66. I see no reason why with a water quench you should be lower than that. You might try 1475 for austentizing as well. Alspdo's orevious batch of 1084 was a bit higher in carbon than usual, 0.87, or 0.89 iirc. You might be getting a bit too much carbon into solution, resulting in retained austentite.

How long are you waiting to RC test the coupons? It can be over 10 minutes for the steel to reach full hardness after the quench. You can correct warp in this time if you are quick. :thumbup: :) I can feel the steel stiffen as I correct the warp on kitchen knives.
 
Mikmerk said:
So, Question... What is the purpose of preheating the canola oil to 130F? And how critical is this step?
Click to expand...

1084 is technically a water hardening steel, but it has enough manganese to get by with a slightly slower quench. Heating the oil decreases viscosity, and increases efficiency of heat transfer. Since your blades aren't hardening correctly, it's critical. I suspect your steel is spheroidized, and the higher carbon stock, causing your problems. Normalize, cycle, and austentize at 1475, quenched in heated canola. Should be Rc65/66. Adjust the austentizing temp up and down 10 degrees at a time and use the temp that gives the highest Rc# with the most consistent results. Then when you get new 1084, do it again as the new steel is slightly different spec.
 
Willie,

It is getting about 66... The hardness tester I have has been consistently 2-3.5 RC soft based on the calibration blocks. Most likely it's because the thing is ancient and I'm sure it needs a good cleaning and lube. When I tested the blocks and the 5160 they read 64 and 66 RC.. so add a couple RC to those...

I've been quenching the letting them sit in the oil until about 120 deg.. then I wash them with soap and water before testing. So about 10 or 15 min from quench.

I can't say thanks enough to you and the rest of the board. I'm learning a ton, even if a bit frustrating. I've got my study notes now.. Off to research Austenite, Martensite, Pearlite, Cementite, Spheroidizing, and Curie.... hehe.
 
This is excellent new and I suspected that was the issue . I never had 1084 not harden . BUT I have had problems with Aldos W2 and 1095 . I suspect I had the wrong steel . I forge those two steels and I always walk them down when completing my forging process . I have a W2 blade that I am doing . This one is not forged .. Stock removal . I will walk it down through the cycles and will admit my mistakes if it hardens .. I am doing a simple blade . so I wont put to much time into it. Trying to make a point. I hope its just me but I can HT with success almost always .. except when I buy from him.
 
This is interesting. I had this problem with some w2. I normalized it and then brought it to 1450 then quenched in parks 50. It was still soft enough for the file to bight into the edge. I heated it a second time and let it soak for 10 mins and quenched. It worked the second time.
 
Mikmerk said:
Willie,

It is getting about 66... The hardness tester I have has been consistently 2-3.5 RC soft based on the calibration blocks. Most likely it's because the thing is ancient and I'm sure it needs a good cleaning and lube. When I tested the blocks and the 5160 they read 64 and 66 RC.. so add a couple RC to those...

I've been quenching the letting them sit in the oil until about 120 deg.. then I wash them with soap and water before testing. So about 10 or 15 min from quench.

I can't say thanks enough to you and the rest of the board. I'm learning a ton, even if a bit frustrating. I've got my study notes now.. Off to research Austenite, Martensite, Pearlite, Cementite, Spheroidizing, and Curie.... hehe.
Click to expand...

My mistake. You did mention the hardness tester issue before.

Have a read through this:

http://www.hybridburners.com/documents/verhoeven.pdf
 
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