Judging Temperature by Eye

[D-weaver]

I was referring to your "snapped" samples in the pic from post #50, immediately prior to my reply in post #51. If you have failure samples, they were subjected to shear forces to impart the failure.

I agree - sorry it's maybe a little obscure. I showed the picture of the shiny spot on the edge first and then snapped samples to see if something similar appeared in them. It does. It may not be the same thing in both.

the difference in the edge quality is extremely unusual, though - I've never seen it before having taken hundreds of pictures. It makes me think the composition of the steel at that spot doesn't match its surroundings.

It's not terminal in plane irons, you can see that the wear looks almost the same, and the carbides still show/look similar, but the spots do impart a different finish on wood. I use the uniformity of the result on wood as an indicator of edge quality and uniformity.

Here is an example of an unfinished piece of wood that's been planed cleanly - it's reflective when viewed along its length which makes it a quick indicator of defects in an edge - even something a thousandth of an inch stands out boldly, as do changes in surface quality. This may not amount to much talking about knives, but for wood plane irons, if you can pick up a piece of wood and see uniformity all the way through the dulling cycle, you know you may not really need to look at anything through the scope.

A poor quality iron will show lines easily, as will one that's undertough (this isn't uncommon on commercial irons), or one that's too tough and not as hard as it should be.

 

[D-weaver]

The last of these trials -after putting aside the stock that doesn't appear to have uniform chemistry, I've got other 1095 that's been sitting here from NJSB and the first shot at adjusted temperatures has yielded a chip free relatively hard (375F temper, so it should be hard) iron.

time will tell if it remains non-chippy in regular use, but - maybe this can be told with knives, and maybe not. The way it cuts wood is more crisp than 1084. It's noticeable - it's also noticeable that 26c3 is another notch up in the same feel trend.

the difference is subtle, but it can be felt. Maybe it's purely hardness potential (and actual hardness), I don't know. The burr characteristics are nice at high hardness - the iron is still easy to sharpen, but on the finish stone, it drops its burr very easily, which is nice in the context of woodworking.

higher light level on the scope to see into the wear bevel. This is the end of my posts on here about hardening and tempering in a forge - it's fine for woodworking, but takes snapping samples and being serious about getting good working characteristics (I didn't have that before with 1084 and 1095). But I also have a whole gaggle of other steels to try either here now or on the way (80crv2, cruforge, another 1095 with more chromium and nickel added, W2, probably forgetting something else)

1095 edge and carbides