Broken blade question

One advantage of O-1 is that it can be hardened from as low as 1450F.Since you are not forging the material the structure will be sheroidize annealed when you start. This is too soft for my tastes.I would first normalize it which would hive you a stronger pearlite structure , then differentially harden - pearlite spine, martensite edge....The second photo is better but why hold it in your hand ? First make sure the two edges [one is usually enough] are in the same plane, tape them together then hold them upright on a table with a C-clamp. Then you can pay attention to the photography, use a tripod too, it's easier...When you want to photo fracture surfaces be very careful with the material - don't touch it with your fingers or scratch it.If you have to remove oil use just a solvent, if necessary you could use a soft brush with the solvent.
 
I agree Roger ,
Mete said you
differentially hardened, yes for sure but you'd get a better hamon edge quenching.
and for you that don't know
differential tempering is done after a full hardening and then drawing the spine down.

it's been mentioned about quenching at nonmagnetic coming down.
I sure do agree with Ed and well put, when I air quench 154CM
and place the blade on my magnetic vise it can look cool (all the color gone from the heat) but I can still
move it around,it would be no different with O1 so I know at non magnetic is just the means to judge a point in heat to quench at, remembering you have to heat another 100 deg or so higher over that point to get the best results on O1 and does apply to other steels also.

I use olive oil (and have used reg, Veggie oil) at about 130 deg, I should use a better and more expensive oil (if better is the word for it) I suppose but some things after years and years I'm a knot head about, :D it works ,
this is what I've used for years and I get very good results with it.
some things can make life easier. but
I like the fact I can go anywhere in a simple setting with a bench grinder
A/O and a kitchen oven and make a simple knife that will work and work well,
in about 1 1/2 hour start to finish with 1 hour used for the temper, this knife may not look pretty in that setting and time frame but it will work and work well.

it sure is good to know all the do's and don'ts to pass on..
personally
I don't think it's necessary to harden O1 and many other steels
more than once if you do it right the first time. of course this is only my opinion. :)
 
Thanks Guys. WHat I will do is be more focused on the 1450 to 1500 color and not the full on 1600 color. I'll do as Hanson and do some test quenches at lower temps. In time I'll have this worked out. After all...my RC test pieces came back consistant(57-59.5) so now its time for my blades to be the same! :eek:
 
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