Help with 1084

G

Gus459

Joined
Dec 2, 2024
Messages
5
First off, I'm a total newbie so I lack a lot of knowledge. My issue is with hardening some sheffield 1084 I recently purchased from Pop's. My process was as follows:
Shaped knife and added bevels to 90% of completion. Normalized steel using propane forge...color was orange and allowed to cool. Probably way to hot. Did two more cycles with slightly less time, pretty sure all were.to hot. Quenched at orange (too hot) and tempered 2 cycles at 420 degrees for 2 hours. File tested and after cutting through the scale it still bit into the blade. Normalized again to red orange and quenched just above non-magnetism. Dark red color. Possibly to cold. Tempered again and the file still bites. I I did place the knife edge on a piece of the original bar and hot a couple times with a hammer and the knife didn't show any damage, but the bar stock did so.it got a wee bit hard anyway. I decided to test a scrap piece and break it. I didn't normalize but went to a higher red heat and quenched. There are prominentstreaks of gold in areas. My question is what's the gold in the grain (carbon) and will normalizing distribute this properly?
 
"My process was as follows:
Shaped knife and added bevels to 90% of completion"

When you say shaped are you talking about forged?
 
I know some 1084 from GFS had hardening issues. I am not sure if the Sheffield 1084 at Pops is from that GFS batch? https://www.bladeforums.com/threads/1084-grain-size-trouble.2014905/

Where are you located? Maybe someone with an actual heat treat oven is near you and can process the steel and see if it's the steel or your process?

We still also need to know the oil; it may be too slow to harden properly? Also, is the blade forged to shape, or stock removal? Steel may be in a coarse versus fine spheroid structure, so it may need more processing/refining before heat treating.

You may get through the scale, but there may be decarb to get through as well? Try drilling in the tang area; if you can drill through it with a regular HSS drill bit, it's still soft. If it bites a bit and then stops partway through, you may be dealing with scale/decarb.

I did a 52100 blade forged, quenched, tempered, ground and then saw weird micro cracks near the spine. Put it in a vise and broke it very easily. It had gold in the grain structure near the spine/cracks and was related to some micro cracking (either forged too hot or too cold) I had, so that's not a good thing to see a gold, red or dark color in the grain! It means air got in there and reacted with the steel, which means there were cracks.
 
Welcome Gus459.
Filling out your profile with location and a bit about you will help a lot with answers. It may also allow a nearby smith to offer help or HT.

There seems to be a strange batch of 1084 floating around. It is so heavily spheroidized it won't harden without a lot of normalizing and other thermal work. The thread Taz linked has the story... so far.

Color is very hard to read as a temperature guide, and different lighting will make it change color as well as different people will see it as different colors. A magnet is your best friend to discover how hot the color is. Non-magnetic will be around 1415°F.
 
Thanks all for your responses. Here's a little more information. I actually made 8 knives (going with a production mentality for Christmas gifts). Used stock removal on 3/16" x 1.5" bar stock and quenched in canola oil.
I just tried to drill through the tang and had no issues...unfortunately. The sample piece, however, was much harder and resistance was encounter within the first 1/32" of an inch. To summarize I think the last quench was too cool. I used a magnet to confirm it had reached non-magnetism, but it needs to be hotter. Thanks again for your assistance!
 
Not sure what that gold color is. Possibly just some surface oxides and scale? You will need to remove all that scale to see if it is soft or not. Scale is glass hard! Grinding it off takes time and isn't fast. Best way to get rid of forging and HT scale is to soak in a bucket of pickle overnight and then scrub off under running water. Pickle is made by using Sodium Bisulfate and water. Sodium Bisulfate is called Ph-Down commercially. You buy it at the hardware store or pool supply companies, (or on Amazon). Mix one cup per gallon to make the pickle.

You need to heat 1084 about 50-70°F hotter than non-magnetic before quenching. 1475° is just about perfect. That is about one shade brighter red than when the magnet stopped sticking.

Canola oil warmed to 130°F works for smaller knives, but your blades may have too much mass to quench in it. 1084 needs a fast quenchant like Parks#50 or Brine.
Use Parks #50 at room temp (60-90°F) and brine at 130-140°F. To make quenching brine, use 3-4 pounds of rock salt or snow melter to 5 gallons of water.

Quenchant temperature is very important. Most quenchants for knives are used around 130°F. Parks #50 is the only exception, and is used at room temp.
 
You must log in or register to reply here.
Back
Top