First, let me say that I did not intend to heat treat this, it is just a scrap of steel I put a bit of a bevel on and a point to use as a sample piece while test firing my ht forge. It's 5/32 ats34.
I had the piece in there for about ten minutes with it no more than dull red, if anything. Then I repositioned the burner to improve efficiency and turn up the heat. Doing that a little at a time using the blade color as a reference. I moved the blade in and out of the heat briefly a few times, trying to figure out if I had any serious hot spots or cool spots in there and that type of thing.
I eventually had the burner where I thought was good and the steel was bright red, starting to go toward yellow. I did not check magnetism or anything along those lines and it only stayed there about five minutes at most while I tested to see if the propane supply would freeze up at the settings I was using. (20lb tank, overkill burner so I am not using it full blast but it still might freeze up the tank if I have it too high for a while.)
When I was done I turned off the burner and pulled the blade out and left it sitting vertically on the bricks so the equivalent of the spine and one other point having contact with the bricks but otherwise just air. It was a breezy 70 degrees out. I left it there till everything was cool enough to touch so I could put it all away and basically forgot about the steel till last night.
I figured what the heck, and took a file to the steel, it skated. Hmmmm, ok, so it at least got hard on the surface, interesting. So I tested the back where it had not been in the heat, yup, soft still. So I decided to run it through the toaster oven at 275 for an hour. Figuring I'd give the low temp/short temper a try since I doubted it was all that hard anyway.
I did that today, then took it outside and ground the edge to an actual edge, rounded off some edges and took off most of the scale toward the blade area (speaking loosely, it only has passing resemblance to a knife). The blade angle is pretty steep but enough to kind of test an edge. I ground it semi sharp then smacked it around a bit with a handy wrench. Minor dings but nothing that stood out as odd. Smacking it pretty hard on the side did nothing. Smacking it on the concrete did nothing (other than dull up the point). It's a fairly short piece but I put it in the vice and put some sideways pressure on it, but minimal bend and no damage other than slight marks from the jaws.
I brought it in and sharpened it up some more, kind of tough with the odd and uneven angle on the edge but it's amusing.
So my question for the experts is why is it surviving? And what is it lacking compared to proper heat treating with the increasing temp soaks and such per the recipe's for ATS34. i honestly expected it to not be hard at all when I took the file to it, and after it skated that I expected it to either break on any real test after the light temper or be too soft for any abuse of the edge.
My SWAG is that I have very incomplete conversion but because the edge spent significantly more time than the rest of it past critical I've gotten enough conversion there (maybe even went over temp, but probably not on time) and less so on the rest of it. I'm not really sure how much of a difference my "quench" had but I would think it was too slow and again, I lost out, but once more, the edge probably cooled nearly fast enough and the rest is softer but still had some conversion. The temper was pretty light, but since I hadn't ever gotten it fully hardened it was probably about right, speaking very generally.
I'm expecting that my edge will not retain sharpness as well as a properly heat treated blade. Otherwise, I am wondering if there's a real loss compared to the correct method. Don't get me wrong, I have no intention of doing it this way again, I didn't really intend to the first time but figured I might learn more by doing a few more steps after I skated the file.
Thoughts, comments, theories? I might clean this sucker up a bit more, grind a better bevel on the blade portion and use it as a shop knife. I forgot my pocket knife the other day and realized I didn't actually have a sharpened blade out there.
I had the piece in there for about ten minutes with it no more than dull red, if anything. Then I repositioned the burner to improve efficiency and turn up the heat. Doing that a little at a time using the blade color as a reference. I moved the blade in and out of the heat briefly a few times, trying to figure out if I had any serious hot spots or cool spots in there and that type of thing.
I eventually had the burner where I thought was good and the steel was bright red, starting to go toward yellow. I did not check magnetism or anything along those lines and it only stayed there about five minutes at most while I tested to see if the propane supply would freeze up at the settings I was using. (20lb tank, overkill burner so I am not using it full blast but it still might freeze up the tank if I have it too high for a while.)
When I was done I turned off the burner and pulled the blade out and left it sitting vertically on the bricks so the equivalent of the spine and one other point having contact with the bricks but otherwise just air. It was a breezy 70 degrees out. I left it there till everything was cool enough to touch so I could put it all away and basically forgot about the steel till last night.
I figured what the heck, and took a file to the steel, it skated. Hmmmm, ok, so it at least got hard on the surface, interesting. So I tested the back where it had not been in the heat, yup, soft still. So I decided to run it through the toaster oven at 275 for an hour. Figuring I'd give the low temp/short temper a try since I doubted it was all that hard anyway.
I did that today, then took it outside and ground the edge to an actual edge, rounded off some edges and took off most of the scale toward the blade area (speaking loosely, it only has passing resemblance to a knife). The blade angle is pretty steep but enough to kind of test an edge. I ground it semi sharp then smacked it around a bit with a handy wrench. Minor dings but nothing that stood out as odd. Smacking it pretty hard on the side did nothing. Smacking it on the concrete did nothing (other than dull up the point). It's a fairly short piece but I put it in the vice and put some sideways pressure on it, but minimal bend and no damage other than slight marks from the jaws.
I brought it in and sharpened it up some more, kind of tough with the odd and uneven angle on the edge but it's amusing.
So my question for the experts is why is it surviving? And what is it lacking compared to proper heat treating with the increasing temp soaks and such per the recipe's for ATS34. i honestly expected it to not be hard at all when I took the file to it, and after it skated that I expected it to either break on any real test after the light temper or be too soft for any abuse of the edge.
My SWAG is that I have very incomplete conversion but because the edge spent significantly more time than the rest of it past critical I've gotten enough conversion there (maybe even went over temp, but probably not on time) and less so on the rest of it. I'm not really sure how much of a difference my "quench" had but I would think it was too slow and again, I lost out, but once more, the edge probably cooled nearly fast enough and the rest is softer but still had some conversion. The temper was pretty light, but since I hadn't ever gotten it fully hardened it was probably about right, speaking very generally.
I'm expecting that my edge will not retain sharpness as well as a properly heat treated blade. Otherwise, I am wondering if there's a real loss compared to the correct method. Don't get me wrong, I have no intention of doing it this way again, I didn't really intend to the first time but figured I might learn more by doing a few more steps after I skated the file.
Thoughts, comments, theories? I might clean this sucker up a bit more, grind a better bevel on the blade portion and use it as a shop knife. I forgot my pocket knife the other day and realized I didn't actually have a sharpened blade out there.
