5160 just wont harden *UPDATE* SOLVED

nateman_doo

nateman_doo

Joined
Sep 16, 2015
Messages
157
I got some 5160 from McMaster, and no matter what I try, it just wont quench. Taking it to 1500°F and dunking in oil. Tried hotter from 1800° to close to 2K, still no luck. I have quenched 1084 & 1095 in the same manner with the same oil, but the 5160 just wont take the edge. Think they goofed and gave me general low carbon steel?

probably my 8th attempt to harden this thing, file still bites into it. (not the 8th consecutive). Is there such a thing as too many attempts? No visible cracks in it.
 
Last edited:
You might want to post this in the knife makers area of the Forum. Under the Forum tab you will see all of the sub forums. There is a general discussion area in the knife makers area. Good luck
 
Since 5160 is Hypoeutectoid you don't have to let it "soak" at or much over the Currey point (basically the magnetic/non-magnetic threshold), just hit it and go a shade over then quench.

How are you moderating your temps?
How are really you reading them?
What is the temp of your quench oil?

Are you file checking after temper?
If so:
How do you temper (what type of oven)?
What temp are you tempering your blades at and for how long?
Are you shielding your blades while in the oven?
 
NJ Bill (does that mean Bill from NJ?? All hail Jersey!!)

I am using my forge. I have a pyrometer which is around where I keep the blade and the burner flame. I file check after I quench in vegetable oil. ordinarily I would blame me for everything, but having quenched other 1084 & 1095 blades I now question the steel itself.

Never made it to the tempering phase. Still stuck at the hardening and quench
 
What is your oil temperature?
Are you thermal cycling your blade?
(Heat to Currey, cool to black in air, then heat back up to just under Currey and cool to black, then heat up to a lower temp for the third time and cool to black, then go back in to bring to temp for your dunk)

If your oil isn't warm enough you could be creating a gas jacket and not getting a fast enough rate of cooling since the oil isn't making enough contact to draw the heat out.
You will want to have your oil around 130°.

How think is your edge when checking with the file?
It is entirely possible (especially after that many tries) that you have a rather thick layer of decarb and you aren't filing through that and into the good hardened steel.

And yes, I am from NJ.
 
Last edited:
I havent thermal cycled it. just kept quenching. really isnt much decarb on the blade though. file check it down to bare metal on the edge itself. I will try to thermal cycle it 3 times from 1700° back to cold. sound like a plan? I dont know what curry is. always thought it was a spice ;)

Morris County here. I get to drive to NJ Steel baron to buy the steel. Been there? He game me a tour of the shop. You wouldnt believe how big, and how many operations are going on there.
 
As I recall, 5160 is roughly 0.6% carbon and not quite the carbon level of either 1095 or 1084. Not to say it wont harden, just that the "as quenched" hardness will be significantly lower. I believe 5160 comes out of the quench with a hardness of roughly 60 Rockwell, whereas 1095 and 1084 have an "as quenched" hardness of 67/68 Rockwell. It might be that the 5160 is hardening, just that it is softer than the file.
 
I would love to stop by the Baron, but I haven't had the opportunity to do so.

The Currey transition can be seen when the room is dark and the alloy is around 1414° which is why you want to HT in a darkened room.
You will see the transition in happen in what will look like a shadow passing through the alloy prior to it turning dark (you will even be able to check one side of the shadow with a magnet and see that it won't stick, while on the other side of it the magnet will).

From what I have read, you will want to bring 5160 up to 1550° and quench in 130° oil and temper at 350° (3 times@2hours) for a "regular" knife and closer to 400 for a chopper.

You will want to file through the bare metal and get into that to find the stuff that has been heat treated. There will be a thin layer of steel that has had the carbon burned out and that will not be hardened. After so many cycles, it is possible that this layer has grown in depth.

I would thermal cycle it to reduce grain growth, bring it up to 1550°-1600° and quench in 130° til black. Then just keep filing until you hit hardened steel and see how deep you have to go.

Chalk it up to a learning experience.
 
UPDATE.

it worked. I normalized it 3 times, and then glass bead blasted the edge, and it quenched like a champ. the scale buildup was preventing the proper quench.
 
Ok first a few things, 5160 DOES need to soak. Not as long as O1 but it's not a steel that you can quench right after it hits temp. I use or used a ton of 5160 and I give it a 10min soak. It's not just the carbon content that affects soak time but also the aloy elaments that affects the rate at which the carbon desolves into solution. In the as quenched state it should skate a file easily as well as snap off with a sharp blow from a hammer. 5160 will harden in just about any oil even slow/med speed oil. My heat treat is as fallows

Heat to 1500°
Soak for 10min
Quench in parks AAA heated to 120°
Then temper to get the hardness your after. Between 350° to 500°

It's really simple steel to work with and if your not getting hardened steel then there is a mix up some where.
 
I did soak it for a while at temp. Just debate for what temp to temper at. its for a hunter that plans to skin a deer. he knows how to use a knife, so i doubt he will abuse the knife, but he doesnt know metallurgy enough to know that if I dont temper it he could chip/shatter it.
 
If he is not planning on using to to split bone or the sternum Then I would run it a tad harder, but geometry is what cuts hardness and wear resistance is what keeps that geometry cutting. I don't see how scale buildup could keep your blade from hardening unless you where using REALLY slow quench oil. I never woried about scale when I quench and most of the time it just pops off in the quench. I have done many normalizing cycles on blades and never had a problem with scale or decarb. Yes there is decarb but it is eather so shallow that I don't notice it or when heating in an oven it scales up and falls off. I could see decarb being a kinda problem when heat treating an as forged blade but even then it's never been very thick for me.
 
see how thick the build-up was?
IMG_20161210_125515_679_zpsnknxiokw.jpg


after hardening:
IMG_20161210_140423_846_zpsipbvnimw.jpg


hopefully if left a quasi-hamon. that would be cool.
 
You must log in or register to reply here.
Back
Top