Avoiding quench lines

bladsmth said:
...Lightly sand the blade to get a clean steel color.Using a hand torch,draw a temper on the ricasso and spine to a blue color.Keep the flame
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Something like this? This is just a little piece I have been using for testing. It is about 4" long. I see the line of blue, but should I be adding the heat so slow that it is blue all the way to the spine? Looks like a second blue line just above the lower one :confused:. Normal?

The line of blue is a little uneven as I don't think I was going slow enough. Got a little close to the tip (or what would be the tip. Just imagine it's not a little cleaver :) ) as well but okay... lessons learned ;) .

heat%20test%202.jpg
 
If the difference in grain growth/hardness is established during the quench, it's a quench line. A quench line is usually very distinct and under maginfication very abrupt.
In Dan's scenero, it would be a temper line but so subltle a change as to often (depending on the steel) be undetectable by the unaided eye and even with magnification is often a very "muddy" transition.
The heat coloration that Nat has shared does not always indicate a "clean" differential in hardness or temper. There are several of variables that affect the reliability of the color array: steel alloy composition, duration of heat soak, and blade geometry being foremost.
Yeah, Brian, he doesn't look the same does he? Spooky change.
 
NOt quite there NAts - Didnt get it hot enough. If you see yellow...its too hot. You want just below a tangarine color. Not dull red. Get scrap and a magnet and learn what color becomes non magnet. Shoot for just above that. The trick is even heat along the edge.
Here's mine from the last temper cycle.

variousfeb2.jpg
 
I think I'm a little confused :( . My pic is of a fully quenched blade that I have drawn the spine to make it soft but keep the hard edge. bladsmth indicated in a previous post the colour I needed to reach and this is hopefully what I have done in the pic.

I did a HT/quench on a blade (not pictured) last night and it turned out really well (I think). Got it up to non-magnetic, full quench and into the oven. It seems to have hardened up real nice. I did the file test on it and it skated right over the edge no problem :)

blgoode - You don't HT the tang at all, just the blade and ricasso?
 
I just get the edge to temperature. I will however heat treat an exposed tang on a knife on the drawing board. Jst to keep it from mushrooming so easily.
I too fully quench.
 
crex said:
Yeah, Brian, he doesn't look the same does he? Spooky change.
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Spooky :confused: :eek: man
you get a hair cut, add a few years and shave the grey out from under the ears and this is what I get :rolleyes: :D :D
this picture was taking at 6:00 am :eek: that was the problem :D
 
Dan,
I was led to belive that annealing a piece of steel was accomplished by bringing the steel to critical temp. then letting it cool slowly through the soft grain structures. When I use clay on the spine of a blade the purpose is to retard it's cooling just enough so it does not make the "harding gate" I don't want it to linger in those temps just below critical that is where the soft structures are to be found. I think its misleading to call it a soft spine or draw. Give me tough but flexable any time. Say yes to clay.
Due to inflation, thats my 48 cents worth I believe. Fred
 
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