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- Sep 9, 2003
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- 2,361
Now as for the lack of normalizing, I honestly don't know where knifemakers got the concept of normalizing right before the quench (perhaps from the abundance of lamellar annealing which could result in larger grain). The purpose of normalizing is to equalize and fix internal structures after very radical procedures like forging and other heavy deformation and temperatures. Industry often only does one at 1600F; this would be very unwise right before quenching. The proper thing to do for steel that has been heavily machined before hardening would be a good old stress relieve, not an all out normalization.
Bladesmiths are fascinated with normalizing because some folks have advanced the idea that there is some fantastic magic in ridiculously small grain size that will turn steel into unobtanium. There is a point of diminishing returns for everything and grains size can become too small to be useful for our purposes, don't get me wrong here I am not endorsing large grain which is universally bad for strength, I am just saying that there is a point where chasing that immeasurably small grain size is counterproductive.
I normalize after forging to fix all the problems that forging can inflict upon a bar of steel. Hand hammers simply cannot deform equally and evenly throughout, while forges and anvils are not the best for perfectly even heating and cooling. I normalize to equalize grain size, evenly distribute carbides and prepare the blade for the subsequent treatments. You can shrink the grain by doing a series of normalizing at the same temp but as the grain size decreases so will the coarsening temperature of those grains (isnt interesting how nature builds these regulators into things, there is always give and take- e.g. the closer you get to the speed of light the more energy it takes to do so, until it becomes impossible to equal or exceed it) . Eventually you will get the grains fine enough that the coarsening temp will equal the normalizing temp, so you will need to keep ahead of it by lowering your heat.
If one is going to go lamellar in the wood ash, then really fine grain may be pointless since to make course pearlite you will have to go to a great enough temp to get total solution, which will reset the grain size according to that temp. This is not a concern for me since I do spheroidal anneals, the spheroidal anneal is subcritical and leaves the grain size alone while balling up the carbides within. This type of anneal can be greatly accelerated by being performed on martensite. My O1/L6 mixture will harden from normalizing heats so I am set, but one working with a forge and 1095 may want to heat the steel to critical and then quench before heating repeatedly to dull read to ball up the carbides.
After my anneal I have the grain size exactly where I want it, I have the carbides where they need to be and the steel is as stress/strain free as I would like for subsequent operations, so there is no need for a treatment before the quench, unless I get really stupid in the grinding (at least one good reason not to turn the steel blue while grinding, and to grind evenly).
Bladesmiths are fascinated with normalizing because some folks have advanced the idea that there is some fantastic magic in ridiculously small grain size that will turn steel into unobtanium. There is a point of diminishing returns for everything and grains size can become too small to be useful for our purposes, don't get me wrong here I am not endorsing large grain which is universally bad for strength, I am just saying that there is a point where chasing that immeasurably small grain size is counterproductive.
I normalize after forging to fix all the problems that forging can inflict upon a bar of steel. Hand hammers simply cannot deform equally and evenly throughout, while forges and anvils are not the best for perfectly even heating and cooling. I normalize to equalize grain size, evenly distribute carbides and prepare the blade for the subsequent treatments. You can shrink the grain by doing a series of normalizing at the same temp but as the grain size decreases so will the coarsening temperature of those grains (isnt interesting how nature builds these regulators into things, there is always give and take- e.g. the closer you get to the speed of light the more energy it takes to do so, until it becomes impossible to equal or exceed it) . Eventually you will get the grains fine enough that the coarsening temp will equal the normalizing temp, so you will need to keep ahead of it by lowering your heat.
If one is going to go lamellar in the wood ash, then really fine grain may be pointless since to make course pearlite you will have to go to a great enough temp to get total solution, which will reset the grain size according to that temp. This is not a concern for me since I do spheroidal anneals, the spheroidal anneal is subcritical and leaves the grain size alone while balling up the carbides within. This type of anneal can be greatly accelerated by being performed on martensite. My O1/L6 mixture will harden from normalizing heats so I am set, but one working with a forge and 1095 may want to heat the steel to critical and then quench before heating repeatedly to dull read to ball up the carbides.
After my anneal I have the grain size exactly where I want it, I have the carbides where they need to be and the steel is as stress/strain free as I would like for subsequent operations, so there is no need for a treatment before the quench, unless I get really stupid in the grinding (at least one good reason not to turn the steel blue while grinding, and to grind evenly).