A couple I'm playing with, the top one is an old farriers rasp, hardened brought home to put in our brand new oven (just got to wait till our lass isn't looking ) The bottom one is from a piece of steel I'd forgotten about, I found it the other day tidying up for the new kitchen. It's RWL34 damasteel, a powder metallurgy made stainless steel named after the famous knife maker Bob Loveless, https://damasteel.se/story-of-rwl34/ I've marked out the holes for the handle and the bevels which I'm going to cut with a file. I haven't decided whether to heat treat it myself or pay someone to do it, I've got a smaller offcut to play with so I'll decide on that outcome.
I'm not quick so don't hold your breath, that top one has been put down in disgust half a dozen times, this is it's fourth heat treat. First heat treat I got a horrendous warp in it so I annealed and straightened it. So then I tried just heating the cutting edge leaving the spine soft, but when I tested it's hardness it was way too soft. So I annealed it again then when I was heating up again I wasn't paying attention and burnt the edge so had to regrind it. Fingers crossed this is going to work, I fully heated and quenched it then while it was still hot clamped it between to lumps of steel and it's nice and straight.
I've not done much with the two knives above, but I made a little kiridashi type knife out an offcut of the rwl 34 to see how it heat treated. I couldn't measure the temp very accuratley (the specs are quite specific). I heated it up to a good colour even though its stainless it is magnetic and it lost its magnetism at that colour, quenched it in oil then stuck it in the oven at home on 180 for a couple of hours which should have made it somewhere in the region of 60 - 64rc but it came out about 53rc at the sharp end it was about 33 untreated. Ideally I want the big blade about 58rc. I've got a couple more offcuts to practice with when I get them right I'll re treat this. The little dot marks are where it was tested
Finished the handle on the farriers rasp knife. It's jute micarta, something I've not tried before, but I'm quite impressed with it. I used my da sander to finish them going down to 500 grit. The bottom pic is just one of the small offcuts I ground up to heat treat. I took this up to bright yellow it needs to be quenched at around 1050-1100 degrees so I'm hoping this is going to be closer .
This tested at 58rc which is cock on for me, but it did pick up a warp which is worrying me a bit. Starting to make a file guide to do the big blade
Chopper look great. Where did you get the info on heat treat? 1050C sounds really hot! I was struggling to get my single burner to take some leaf spring up to red heat earlier today.
Interesting. Is that what those rasps are made from? Dammit, I bought a job lot and gave half of them away already! <edit> I think we're talking cross purposes. That's the offcut of knife steel you're talking about. How do you get it to 1050C and how do you know when it gets there? I may have to upgrade my home made forge thing, extra burner at least, maybe forced air.
No idea what the rasps are, I just heat them till they lose their magnetism and temper then in the oven. I just went by colour for the kiridashi and tiny cleaver, but when I get round to the big knife I'll put a couple of pieces of copper on it copper melts at about the right temp. I use either the forge or oxy propane, either will get it hot enough, a single burner tuned and made right should easily get hotter than that or you'll never be able to forge weld, extra burners just increase the amount of metal you're able to heat not increase the temp
The copper trick is brilliant thanks, guess it also applies to other metals. I use a cheapo infrared thing but it bugs out over 800C (if even that is to be believed). I think you're right about the burner, I never did get around to dialling it in. At the very least I need to know what pressure I am feeding it at. Good to know it should work at least. The forge is certainly a decent build but possibly a bit too big and while I have decreased the volume with extra firebrick etc. I may need to re-line it with heavy duty brick to keep the heat in for longer sessions. First time I have fired it up for a long time, I might even wait until it gets a bit cooler. Meantime I'll be doing a few more stock removal projects...
Do they say you can get 60 Rc ?....usually 420 type grades dont get much harder than 50-55 Rc....you need the 440C (higher Cr) to get to 60-65Rc
https://damasteel.se/wp-content/uploads/2019/01/Data-Sheet-RWL34.pdf The data sheet doesnt quote 1050 oC for annealing
This is data for 420 steels....not much different to the RWL mentioned https://www.azom.com/article.aspx?A...teel grades that are,and the grade 440 series.
Some good info from Sandvik.....interestingly they quote 1060 oC for annealing....much higher than RWL.. https://www.materials.sandvik/en-gb/materials-center/material-datasheets/strip-steel/sandvik-19c27/ I usually follow what Sandvik quote as gospel....they dont get much wrong....except their customer service which is dreadful
