Nope, I don't think I said anything about relieving stresses - did I?
It's mostly for even distribution of alloys and grain refinement. In that respect, yes there are stresses, but it's stresses from uneven distribution of the alloys creating different steel structures throughout the blade.
Truth of the matter is, you have NO IDEA of the condition of that steel. NO IDEA of what mill it came from or how it was treated.
When you thermal cycle in three REDUCING HEAT steps, with good heat control for EVEN heating of the target steel, you DISSOLVE the alloy for even distribution and in the cooling process enhance grain refinement.
I always think of different steel types as different types of cakes with different ingredients.
We have "simple" tool steels and we have "high alloy" steels.
A simple cake would only have flour, egg, water, just basic ingredients.
Wouldn't take much to get all of that dissolved and evenly distributed.
But as soon as you begin to make a more complex cake, with a lot more ingredients, the more stirring, the more heat and the more TIME is needed to evenly distribute the ingredients and the more time in the oven to get it cooked.
For example, to austenize 1084 for hardening, you barely need to get it much more than non-magnetic (1414) and quench in something wet! It has very few ingredients.
But, to do it properly, 5160, because of all the chromium and other alloys, needs to soak at 1525-1550 for a GOOD! 20 minutes.
A LOT more heat and a LOT more time.
I know I'm going on here, but just to delineate between simple steels and complex steels.
Is it important to thermal cycle blade steels?
I can come up with a lot more reasons to do it than to not do it.
But make sure to do it in REDUCING HEATS!!
If a subsequent heat cycle goes ABOVE the previous cycle, then you just lost overything you were trying to gain!
Go HOT on that first one to dissolve all the alloy and let cool to black, then right back in the heat.
Heat the second time to a nice even orange color well above non-mag, but not as hot as the first time. Once again, just back to a black heat, which will be about 900 degrees.
On the third one, just to non-mag and let cool to room temp.
It's a really basic procedure, but better than NOT doing it.
Topic: Normalizing (Read 903 times)
