Attachment 206103
Attachment 206105
Printable View
By the chart I am reading online it looks like I may be down to rc 60 or even less!
Should I re-quench?
I think I would. If you like softer razors they might be alright, but once you do the final grind your kind of stuck with your choice.
It was on the bottom shelf of the oven, close to the element. About an hour at 350oF, and then I cranked it to 450oF for another hour. This is O1.
I also didn't soak the blades very long, because I had them held with tongs in one hand while holding the torch in the other (my old micro forge doesn't get hot enough unless everything is held just right). They were good lively orange and then quenched into canola oil.
I have zero experience with 01 that is tempered that far back. It might be OK.
On the other hand, a second quench may dissolve more of the carbides since you were unable to soak for very long.
Did you check the color at the end of the 350* period? My kitchen oven tempers to light straw when set at 350?
Do they skate a not new but not worn out file? Colors can be sometimes inexact science. I can't see the colors on the bevel/edge portions very well from these pictures. The purple is not on the working edge anyway so that's not a problem. I like the gold color, that usually speaks well of adequate hardness but it's only on the spine.
350 F would not have been bad to start, but 450 F may have been too much.
I'll check. The blades still had the carbon left on them from the quenchant.
You will not be able to check. I was asking about the color after tempering at 350 and before the 450.Quote:
Originally Posted by Atchbo
Also these colors are oxidation colors, so the steel has to be sanded bright a little bit before heating. I always sand a bit of the blade before tempering for this reason, kind of a sanity check and a verification of my kitchen oven temp adjustment.
I meant check with the file. I didn't see much if any colour after the 350 step, which is why I went up. The rest of the razors' surfaces were sanded to 240 or 400 grit because I remember what a pain it was last time sanding hardened O1. I should have continued a bit further into the blades but thought the carbon might help reduce decarburization... Or I'm lazy!
With a proper soak, etc, 350 should give you 64-65 and 450 60-61. Of course there is a big IF in there.
I just noticed that in the pictures, the darker colours seem to be on the tangs, where they may not have been quenched (or not as much). I'll see if I can verify this as well as the file test. If it's not so soft that the file bites I'll continue on.
Attachment 206167
I think they're ok.
On second thought, the file seems to cut.Attachment 206168
Attachment 206169
However, they didn't do this before tempering, and if the file is rc65 and the steel is 59, this is expected, no? The file 'almost' skates unless you use pressure.
I use my oven too, but I let it stabilize in heat before I add the blades and I use the center of the oven. Using the bottom of the oven close to the heat can lead to finding hot spots. Hot spots on the thin metal (the important part...the edge) can get them a lil soft.
You can take a chance and do the final grind...or just HT again & play it safe.
Using a cooking oven can be done. It has the risk that the set point for the temperature can swing too low or too high depending on the accuracy of the controller and thermocouple sensing system. Sometimes as much as 50 degrees or more. A loaf of bread probably doesn't matter so much. But, you can, over time and a bunch of blades, fiddling with the temperature setting and checking the hardness develop a familiarity with the oven that can overcome some of the error and you can get pretty reliable after a while.
Looking at the new pictures I see a nice color down to the edge. Well it looks like a color I would be happy with.
I agree with Shooter, take a chance or HT again and this time stay below 400F in the temper. If it's a bit lighter yellow/straw you're good. There is nothing wrong with Rc 59. The fellows who have to hone blades will thank you for caring about their feelings. LOL
Ok, I did. Probably wasn't necessary by the feel of it on the belt grinder beforehand. I sanded them up and then put them in the forge while it came up to temp. Then when orange and non-magnetic, quenched in canola, and then sanded again.
I coated the blades with fire clay but I think that was a waste of time, as it all flaked off the blades and the only parts that stuck were probably wet (on the sides of the shoulders) and was a pain to sand off.
Thanks guys. In retrospect, if the colour looked ok for Mike Blue, I should have left it rather than risk grain growth, but hey, it's all experience.
Seems a shame to use the oven in summer but I will try to keep these moving. I might try the convection setting on the microwave/oven (no nuke of course).
You were the one with the blade in your hand at the time. All of us can have an opinion from a distance, but it's the fellow with the job in front of them that has to make the decision. Usually, heat treatment temperatures won't affect grain growth if they are above austenitizing temperature and below the coarsening temperature.Quote:
Originally Posted by Atchbo
A lot of forges are not controlled as well as they could be, and then grain growth can be a potential issue. Basically the forge is On or Off and there is little adjustment of the fire in between. You're HTing ten blades, the first three turn out okay but the last seven all have problems. The forge continues to run upward from a good temperature to screaming hot by the time the job is done. Eventually you learn to do three blades and quit and let the fire cool down and do the rest in batches later (the less expensive method).
A well controlled fire will hold the same temperature consistently no matter how long it runs. One of my small forges (a Randal Graham design) will hold a set temperature until the gas runs out. Blades can sit there for a long time without overcooking. I've had to "tune" it, using the wet computer, a bit for different altitudes and relative humidity. Once the adjustments are made it's a fine little fire. Salt tubes operate similarly whether electric or gas, but then you have solenoid controllers and such (expensive).
If the blade shaves you did a good job. If it hones harder, or easier, the man with the stones will tell you. Each blade will talk to you and tell you what it wants. LOL
I just want to add that 57 and 58 are not exception among old Sheffield razors, so that shouldn't be a problem at all as long as you stay above 57.
One hour at 400oF.
Attachment 206305
Attachment 206306
With flash
Attachment 206307
Up close
That looks very close to the color that I have been tempering to.Quote:
Originally Posted by Atchbo
I only have experience honing one old Sheffield, but that one was too soft for my taste. YMMVQuote:
Originally Posted by Bruno
